Lect 1
Introduction to Biochemistry
1. Briefly explain about basic chemistry.
Atom: the smallest particle of an element and it retains characteristics of element. Each atom has an equal no of proton and electron(electrically balanced). Each atom has ability to work(chemical energy from electron).
Nucleus: center of an atom, contain protons and neutrons.
Proton: Positively charged.
Neutron: Neutral.
Electron: move in regions outside the nucleus. Negatively charged.
Element: substances that cannot be broken down into simpler substances. It consists only one atom. Ex: H, O, C. Each element has a set of properties that distinguish it from the others. Ex: O2 is odourless/colourless at room temperature.
Molecule: smallest unit of compound. It has properties of compound. Ex: ratio H:O=1:2, formula is H2O.
Ion: electrically charged (+/-) molecule
Compound: substances made from elements. Chemical formula shows kind and proportions of atom. Ex: salt NaCl.
2. Briefly explain about organic and inorganic compounds.
Organic compounds: contain C, H, O in some ratio. Ex: carbohydrate, lipid, protein, nucleic acid.
Inorganic compounds: no specific ratio C, H, O. Usually for "support" life. Ex: H2O, CO2.
3. Briefly explain about organic chemistry.
Branch of chemistry which deals with carbon based compound.
4. Briefly explain about carbon compound.
Carbon compound found in gases, aqueous, solids forms.
5. Carbon cycle.
6. Briefly explain about organic and inorganic molecules.
Organic molecules: contain C, H. Usually larger than inorganic molecules. Dissolve in water and organic liquids.
Inorganic molecules: generally do not contain C. Usually dissociated in water, forming ions.
7. Briefly explain about organic and inorganic substances.
Organic substances:
a. Carbohydrate: provide energy and supply materials to build cell structures. Water-soluble. C6H12O6(H:O=2:1)
Monosaccharides: fructose, glucose
Disaccharides: sucrose, lactose
Polysaccharides: glycogen, cellulose
b. Lipid: non water-soluble, soluble in organic solvent.
Fats: used primarily for energy. C57H110O6(O less than carbohydrate). Building blocks: 1 glycerol and 3 fatty acids per molecule. Saturated and unsaturated.
Phospholipids: major components of cell membrane. Building blocks: 1 glycerol, 2 fatty acid, 2 phosphate per molecule. Hydrophilic head and hydrophobic tail.
c. Protein: structural material. Energy source. Hormones, receptors, enzymes, antibodies. Building blocks: amino acids.
d. Nucleic acid: carry genes. Encode amino acid sequence of proteins. Building blocks: nucleotides.
DNA: double polynucleotide
RNA: single polynucleotide
Inorganic substances:
a. Water: most abundant compound in living material. 2/3 in human body. Major component of all body fluids. Medium for most metabolic reactions. Transport chemical, absorb and transport heat.
b. O2: for survival. Used for organelles to release energy from nutrients in order to drive cells metabolic activities.
c. CO2: waste product released from metabolism.
d. Inorganic salts: abundant(exist plenty of) in body fluids. Source of necessary ions(Na+. Cl-, K+, Ca2+). For metabolism.
8. Briefly explain about chemical bonds.
Ionic bond: transfer e. Positive charge atom loss e, negative charge atom gain e and form ion.
Covalent bond: share e. Molecule. More chemical bonds a molecule, more energy it contains.
9. Noncovalent interactions in biomolecules.
a. Charge-charge interactions
b. Hydrogen bonds
c. Van der Waals forces
d. Hydrophobic interactions
10. Briefly explain about mixture.
Mixture is a composed of two or more elements or compounds that are physically mixed. Different substances are not chemically joined together. Homogenous mixture can be defined as the mixtures which posses the same properties and combination throughout their mass whereas heterogenous mixture posses different properties and compositions in various parts.
11. Briefly explain about solution.
Solution can be prepared with a solute and a solvent.
It is a homogenous mixture. A solute dissolves in a solvent.
Suspension is
prepared with materials that do not dissolve, for example: blood. It is a
heterogenous mixture.
12. Briefly explain about formula.
Formula shows the chemical symbols and number that compose a compound. Structural formula shows the line drawings of the compound, the arrangement of atoms and how the elements bonded together. Molecular formula shows the actual number of atoms for a compound.
13. Briefly explain about functional group.
a. Hydroxyl -OH
b. Carbonyl -CO/COH
c. Carboxyl -COOH
d. Amino -NH3
e. Sulfhydryl -SH
f. Phosphate -PO4
g. Carboxylate -COO-
14. Briefly explain about biochemistry.
Biochemistry is the application of chemistry to the study of biological processes at the cellular and molecular level. It is a sub-discipline of biology, chemistry, and physiology to investigate chemistry of living systems. It uses the methods of chemistry, physics, molecular biology, and immunology by studying the structure and behavior of the complex molecules found in biological material and the ways these molecules interact to form cells, tissues and whole organism.
15. Principle of biochemistry.
cells are highly organized and constant source of energy is required to maintain the ordered state
living processes contain thousand of chemicals pathways,
certain important pathways, glycolysis
all org uses same molecules: carbohydrate, lipid, NA, protein
instructions for growth, reproduction & developments is encoded in DNA
16. Cell.
building blocks of life
smallest living unit
grow, reproduce, use energy, adapt, respond to their environment
17. Macromolecule of cell.
a. carbohydrate
CxH2xOx
starch, glucose, cellulose
generally used for energy
b. protein
used for structure and support
made up of amino acids
c. lipid
fats and oils
d. nucleic acid
DNA and RNA
composed of sugar, phosphate groups and nitrogen bases
18. History of biochemistry.
Neuburg: 1903, discover role of enzymes as catalysts and identification of nucleic acids as info molecules (from nucleic acid to protein)
Krebs: 1937, citric acid (Noble physio or med 1953)
Watson & Crick: 1953, DNA double helix (Noble 1962)
Human Genome Project
19. Biomolecule.
Building blocks of cells. Animal and plant cells contain approximately 10,000 kinds of biomolecules. Water constitutes 50-95% of cells content by weight. Ions like Na+, K+ and Ca²+ may account for another 1%. Almost all other kinds of biomolecules are organic (C, H, N, O, P, S). Organic compounds are compounds composed primarily of a carbon skeleton.
a.small molecule
lipid, phospholipid, glycolipid, sterol
vitamin
hormone, neurotransmitter
carbohydrate, sugar
b. monomer
amino acid
nucleotide
monosacchride
c. polymer
peptide, oligopeptide, polypeptide, protein
nucleic acid
oligosacchride, polysacchride (including celluolose)
Lect 2
Water
1. Briefly explain about the polar covalent bonds result in hydrogen bond.
Water is polar molecule (opposite end opposite charge)
Polarity allows formation of hydrogen bonds
2. Determine the properties.
Resist change of state and temperature:
Absorb/release a large amount of heat with slight of change in it's temperature
Specific heat (amount of heat absorb/release-1g-to change temperature by 1°C)
Trace to hydrogen bond (absorb heat, bond break, vice versa)
High specific heat minimizes temperature fluctuations within limits that permit life
Universal solvent:
Aqueous solution (water as versatile solvent)
Hydration shell form
Polarity allows formation of hydrogen bond
Cohesive and adhesive:
Hydrogen bond hold molecules
Transport of water against gravity in plant
Attraction btwn different substance (water& cell wall)
High surface tension:
How hard to break liquid surface
Less dense as ice than as liquid:
Expansion upon freezing
Ice floats, hydrogen bond more ordered/stable
Water reaches greatest density at 4°C
3. Define pH.
Negative log of concentration of H+
4. Define buffer.
5. Importance of water, acid, bases and buffer.
Ionization of water
Lect 3
NA
1. Define NA.
The basic building blocks of nucleic acids are the nucleotides.
Nucleic Acids are macromolecular structures which store and express all the information necessary for building and maintaining life.
DNA (Deoxyribo Nucleic Acid) is considered as the repository of the genetic information.
RNAs (RiboNucleic Acids) is functioned as vectors and translators of the information.
A Nucleotide consists of :
a nitrogenous base: purine (Adenine (A) or Guanine (G)) or pyrimidine (Cytosine (C) or Thymine (T) (or Uracil (U)in RNA)).
a sugar : Deoxyribose (DNA) or Ribose (RNA).
a phosphate group
A Nucleotide is a phosphorylated nucleoside.
Inter-nucleotide linkages are formed by a phosphodiester bond between a 5'-phosphate group and the 3'-hydroxyl group of the next nucleotide sugar.
Nucleotides are the monomeric unit of each nucleic acid.
The Base: Heterocyclic Amine
• Purines :
Adenine (A) Guanine (G)
• Pyrimidines :
Cytosine (C) Thymine (T) Uracil(U)
The sugar: five-membered cyclo-ring
D- Deoxyribose D- Ribose
The phosphate group
Nucleoside: base+sugar
AGCT
2. Describe the structure and function of NA.
DNA:
Backbone Alternate phosphate and sugar (deoxyribose), phosphate ester bonds
The structure of DNA leads to transmission of hereditary traits.
double helix structure with 2 strands of DNA; antiparallel
RNA:
Single stranded
Ribose Sugar
5 carbon sugar
Phosphate group
Adenine, Uracil, Cytosine, Guanine
3. DNA
4. RNA
Messenger RNA (mRNA) – transfers DNA code to ribosomes for translation.
Transfer RNA (tRNA) – brings amino acids to ribosomes for protein synthesis.
Ribosomal RNA (rRNA) – Ribosomes are made of rRNA and protein.
5. Briefly explain about protein synthesis
Process involve transcription & translation.
Transcription:
RNA molecules are produced by copying part of the nucleotide sequence of DNA into complementary sequence in RNA
RNA polymerase binds to DNA and separates the DNA strands. RNA polymerase then uses one strand of DNA as a template from which nucleotides are assembled into a strand of mRNA.
RNA Polymerase looks for a region on the DNA known as a promoter, where it binds and begins transcription.
RNA strands are then edited. Some parts are removed (introns) - which are not expressed – and other that are left are called exons or expressed genes.
Translation:
conversion by tRNA to protein
cell uses info from messenger RNA
A – Transcription occurs in nucleus.
B – mRNA moves to the cytoplasm then to the ribosomes. tRNA “read” the mRNA and obtain the amino acid coded for.
C – Ribosomes attach amino acids together forming a polypeptide chain.
D – Polypeptide chain keeps growing until a stop codon is reached.
6. Briefly explain about genetic code.
language of mRNA
based on 4 bases of mRNA
3 RNA sequences=codon
mRNA contains codon which code for amino acids
Base Triplets=code for specific amino acids
Lect 4
Amino acid(aa) and protein
1. Define amino acid and protein.
amino acid:
component of peptides, proteins, phospholipids
neurotransmitter: glutamate, aspartate, glycine
precursor of: keto acids, biogenic amines, glucose, nucleotides, heme, creatine
transport molecule of NH2 grp
buildig blocks of protein
Structure of aa:
a. amino acid grp(basic)
b. carboxyl grp(acidic)
c. alpha carbon(attached H atom)
d. R grp(variable) different side chain, determine properties of aa
protein:
linear polymers of amino acid
21 amino acid (9 essential+12 non-essential)
globular/fibrous forms
2. Determine the characteristics of amino acid.
most aa chiral, 4 different substituents attached to alpha-carbon (glycine is the only exception bcaz R grp is H)
aa have 2 possible steroisomers except glycine (D-/L- enantiomers) mirror images
prefixes D- and L- assigned based upon similarity to D- and L- glyceraidehyde
proteins are made from L-aa (D-aa are found in bacterial cell w all and antibiotic, relatively rare in nature)
aa canbe categorized as hydrophobic (non polar), polar & uncharged, polar & charged based upon nature of R grp
3. Briefly explain about synthesis of amino acid.
many org can make all of 20 aa (bacteria, yeast, plants)
Protein balance:
+ve:synthesis>degradation (growth, body building)
-ve:synthesis<degradation (starvation, trauma, cancer cachexia)
Benefit of aa: https://www.youtube.com/watch?v=Sw-kLCn2Kd0
4. acid/base properties of aa.
acid(proton donors), base(proton acceptors)
pKa:
low, relatively "strong" weak acid
high, relatively "weak" weak acid
low, relatively "weak" weak base
high, relatively "strong" weak base
https://www.youtube.com/watch?v=9Qi3225yrmw
5. Briefly explain about peptide bond.
link aa to form peptides & proteins (C-N)
protein is long peptide, contain 100-1000 aa residues
indirectly removal of elements of water
linkage btwn aa
6. Determine 3D of 4 levels of protein structure.
Primary: aa linear sequence
Secondary: regions of regularly repeating conformations of peptide chain, such as alpha helices and beta sheets (aba)
Tertiary: describes shape of fully folded polypeptide chain, 3D secondary structures
Quaternary: arrangement of 2 or more polypeptide chains into multisubunit molecule
https://www.youtube.com/watch?v=PPJ7C3hcnPw
7. Briefly explain about function of protein.
Catalysis: almost all chemical reactions are catalyzed by protein enzymes
hydrolysis:
condensation:
Transport: transport O2(hemoglobin), ions
Info transfer: hormone
regulation and protection
8. amino acid sequence is encoded by DNA base sequence in a gene
9. protein denaturation
broken chemical bonding in protein, the shape unravel, alter intended function
coagulation
alcohol kill bacteria by damaging protein
experiment: egg tightly bound, can use heat, acid, salt, acetone to denature
Lect 5
Carbohydrates
1. Define carbohydrates.
a major source of energy from diet
composed of C, H, O
sacchride=sugar
biomolecule
produced by photosynthesis in plants
glucose synthesized in plants from CO2, H2O and energy from sun
oxidized in living cells(respiration) to produce CO2, H2O and energy
2. Determine the importance of carbohydrate.
provide energy through oxidation
supply carbon for cell component synthesis
serve as form of stored chemical energy
form part of structures of some cells and tissues
3. Fischer projections.
represent carbohydrate
places the most oxidized group at the top
shows chiral carbon as intersection of vertical & horizontal line
4. Determine the types of carbohydrate.
Monosacchride, Disacchride, Polysacchride
5. Classify carbohydrate.
Simple sugar: monosacchride, disacchride
Complex carbohydrate(polysacchride): starch, glycogen, cellulose(form of fiber)
6. Monosacchride
3-6 C atom, carbonyl group(aldehyde/ketone)
a. Aldoses
contain an aldehyde group and many hydroxyl (-OH) group
b. Ketoses
contain a ketone group and many hydroxyl (-OH) group
7. Classification of monosacchride
a. Glucose
dextrose
sugar to which all others are converted after absorption occurs in liver
cell's preferred source of energy under most conditions the brain requires it as energy
natural food source of glucose are limited, honey contains glucose
Blood glucose/sugar level:
In the body,
Glucose has a normal blood level of 70- 90 mg/dL.
A glucose tolerance test measures blood glucose for several hours after ingesting glucose.
b. Fructose
fruit sugar
sweetest
source: fruits, honey, added-high fructose corn-syrup is often used to sweeten food
too much of it can draw water into GI tract and cause disease
c. Galactose
single sugar
not very sweet
not found naturally in many food
found in "lactaid" milk
8. Disacchride
made by joining 2 monosacchrides by a chemical bond
glucose is component of disacchride
a. maltose
glucose--glucose
made when starch break down
find in some barley
made during fermentation-alcohol synthesis
digestion occurs in smooth intestine, breaks bond btwn glucose molecules, requires presence of SI enzyme maltase
absorption
produced during germination of seeds and fermentation
b. sucrose
glucose--fructose
made from sugar beets and sugar cane
fairly sweet
food sources
table sugar
digestion occurs in smooth intestine, enzyme sucrase
absorption
c. lactose
glucose--galactose
milk sugar
food sources: milk, ice cream, sherbet, small amount in cheese and yogurt
digestion in smooth intestine, enzyme lactase
absorption
9. Digestion
10. Polysacchride
polymerization
polymer of glucose
Glucose=O2-----CO2=H2O (respiration)
a. glycogen
very compact that results from coiling of polymer chains, compactness allows large amounts of carbon energy to be stored in a small volume, with little effect on cellular osmolarity
Function: animal storage form of glucose, stores in liver and muscle
Structure:
~million glucosenjoined by alpha glycosidic bonds
highly branched every 5-6 glucose
food sources: none(make glycogen from extra glucose)
b. starch
digestion and absorption: mouth, stomach, small intestine
Function: plant storage form of glucose, plant sources, majority of carbohydrate in starch form
Structure:
~100,000 glucose joined by alpha glycosidic bonds
2 form:branched(amylopectin-branches every ~20 glucose) & coiled(amylose)
c. cellulose
long, unbranched chains that coil around each other to form fibers, very strong
polysacchride fibers
no enzymes needed for bond digestion
Function: structural component of all plant cells
Structure:
many glucose bonded by beta glycosidic bonds
11. Digestion of dietary
12. Determine the chemical test for carbohydrates.
a. Molisch's
b. Iodine
c. Benedict's
d. Barfoed's
e. Seliwanoff's (aldo, keto sugar)
f. Osazone
13. Hydrolysis: split molecules and commonly occur during digestion.
14. Condensation: link together.
Lect 6
Lipid
1. Define lipid.
Biomolecules that contain fatty acids or a steroid nucleus.
Soluble in organic solvents but not in water. Hydrophobic.
Greek: lipos=fat.
2. Determine types of lipid.
Waxes.
Fats and oils (triacylglycerols).
Glycerophospholipids.
Prostaglandins.
3. Determine structures of lipid.
4. Fatty acids.
Are long-chain carboxylic acids.
Typically contain 12-18 carbon atoms.
Are insoluble in water.
Condensed formulas.
Line-bond formulas.
For example caprylic acid with 8 carbon atoms. CH3—(CH2)6—COOH
Can be:
a. Saturated
Single C–C bonds.
Molecules that fit closely together in a regular pattern.
Strong attractions between fatty acid chains.
High melting points that make them solids at room temperature.
b. Unsaturated
Have one or more double C=C bond
Typically contain cis double bonds.
Have ―kinks in the fatty acid chains.
Do not pack closely.
Have few attractions between chains.
Have low melting points.
Are liquids at room temperature.
c. Omega-6 & Omega-3
In vegetable oils are mostly omega-6 with the first C=C at C6.
linoleic acid
CH3─(CH2)4─CH=CH─CH2─CH=CH─(CH2)7─COOH
In fish oils are mostly omega-3 with the first C=C at C3.
linolenic acid
CH3─CH2─(CH=CH─CH2 )3─(CH2)6─COOH
5. Prostaglandins.
20 carbon atoms in their fatty acid chains.
An OH on carbon 11 and 15.
A trans double bond at carbon 13.
Produced by injured tissues.
Involved in pain, fever, and inflammation.
Not produced when anti-inflammatory drugs such as aspirin inhibit their synthesis.
6. Waxes.
Esters of saturated fatty acids and long- chain alcohols.
7. Fats and oils.
Also called triacylglycerols (TAG/triglycerides).
Esters of glycerol.
Produced by esterification.
Formed when the hydroxyl groups of glycerol react with the carboxyl groups of fatty acids.
Triacyglycerols:
Glycerol forms ester bonds with three fatty acids.
The chemical reactions of triacylglycerols are similar to those of alkenes and esters.
In hydrogenation, double bonds in unsaturated fatty acids react with H2 in the presence of a nikel (Ni) catalyst.
In hydrolysis, ester bonds are split by water in the presence of an acid, a base, or an enzyme.
Olive oil:
Contains a high percentage of oleic acid, which is a monounsaturated fatty acid with one cis double bond.
Melting points:
A triacylglycerol that is a fat
Is solid at room temperature.
Is prevalent in meats, whole milk, butter, and cheese.
A triacylglycerol that is an oil
Is liquid at room temperature.
Is prevalent in plants such as olive and sunflower.
Oils:
Have more unsaturated fatty acids.
Have cis double bonds that cause ―kinks in the fatty acid chains.
Cannot pack triacylglycerol molecules as close together as in fats.
Have lower melting points than saturated fats.
Are liquids at room temperature.
8. Hydrogenation of oils
Adds hydrogen (H2 ) to the carbon atoms of double bonds.
Converts double bonds to single bonds.
Increases the melting point.
Produces solids such as margarine and shortening.
Trans & Cis unsaturated fatty acids:
Trans have bulky groups on opposite sides of C=C. Cis with bulky groups on same side of C=C.
Trans fatty acids :
Are formed during hydrogenation when cis double bonds are converted to trans double bonds.
In the body behave like saturated fatty acids.
Are estimated to make up 2-4% of our total Calories.
Are reported in several studies to raise LDL- cholesterol and lower HDL-cholesterol.
9. Hydrolysis
Triacylglycerols split into glycerol and three fatty acids.
An acid or enzyme catalyst is required.
10. Saponification
Is the reaction of a fat with a strong base.
Splits triacylglycerols into glycerol and the salts of fatty acids.
Is the process of forming ―soaps (salts of fatty acids).
With KOH gives softer soaps.
11. Glycerophospholipid
The most abundant lipids in cell membranes.
Composed of glycerol, two fatty acids, phosphate and an amino alcohol.
Lecithin and cephalin are glycerophospholipids
Abundant in brain and nerve tissues.
Found in egg yolk, wheat germ, and yeast.
12. sphingolipid
Are similar to phospholipids.
Contain sphingosine (a long-chain amino alcohol), a fatty acid, phosphate, and a small amino alcohol.
Have polar and nonpolar regions.
In sphingomyelin, a sphingolipid found in nerve cells
There is an amide bond between a fatty acid and sphingosine, an 18-carbon alcohol.
A class of lipids containing a backbone of sphingoid bases, a set of aliphatic amino alcohols that includes sphingosine
13. Glycosphingolipid
Glycosphingolipids contain monosaccharides bonded to the –OH of sphingosine by a glycosidic bond.
Are sphingolipids that contain monosaccharides.
Can be a cerebroside with galactose.
14. cerebroside
15. Steroids
A steroid nucleus consists of
3 cyclohexane rings.
1 cyclopentane ring.
No fatty acids.
a. Cholesterol
Is the most abundant steroid in the body.
Has methyl CH3- groups, alkyl chain, and -OH attached to the steroid nucleus.
Cholesterol in the body :
Is obtained from meats, milk, and eggs.
Is synthesized in the liver.
Is needed for cell membranes, brain and nerve tissue, steroid hormones, and Vitamin D, bile.
Clogs arteries when high levels form plaque.
Cholesterol in food is :
Synthesized in the liver.
Obtained from foods.
Considered elevated if plasma cholesterol exceeds 200 mg/dL.
Disease: heart attack, stroke, peripheral artery disease, atherosclerosis, hyperlipidemia
Good cholesterol: HDL-artery-liver-bile salt
Bad cholesterol: LDL
Ways to lower LDL raise HDL: Heart healthy diet, exercise, healthy weight, no smoking, medications
b. Bile salts
Are synthesized in the liver from cholesterol.
Are stored in the gallbladder.
Are secreted into the small intestine.
Have a polar and a nonpolar region
Mix with fats to break them part.
Emulsify fat particles to provide large surface area. (Emulsification)
Alkaline
c. Lipoproteins
• Combine lipids with proteins and phospholipids.
• Are soluble in water because the surface consists of polar lipids.
Include low-density lipoprotein (LDLs) and high-density lipoprotein (HDLs).
d. Steroid hormones: Adrenal corticosteroids
Steroid hormones:
Are chemical messengers in cells.
Are produced from cholesterol.
Include sex hormones such as androgens (testosterone) in males and estrogens (estradiol) in females.
Adrenal corticosteroids are steroid hormones that
Are produced by the adrenal glands located on the top of each kidney.
Include aldosterone, which regulates electrolytes and water balance by the kidneys.
Include cortisone, a glucocorticoid, which increases blood glucose level and stimulates the synthesis of glycogen in the liver.
e. Anabolic steroids
Are derivatives of testosterone.
Are used illegally to increase muscle mass.
Have side effects including fluid retention, hair growth, sleep disturbance, and liver damage.
Lect 7
Metabolism
1. Describe about metabolism.
Cellular metabolism
◦ Cells break down excess carbohydrates first, then lipids, finally amino acids.
◦ Nutrients not used for energy are used to build up structure, are stored, or they are excreted
◦ 40% of the energy released in catabolism is captured in ATP, the rest is released as heat
2. Describe about anabolism. (Join)
Performance of structural maintenance and repairs
Support of growth
Production of secretions
Building of nutrient reserves
3. Describe about catabolism. (Breakdown)
Breakdown of nutrients to provide energy (in the form of ATP) for body processes
◦ Nutrients directly absorbed
◦ Stored nutrients
4. Describe about carbohydrates metabolism.
Primarily glucose
◦ Fructose and galactose enter the pathways at various points
All cells can utilize glucose for energy production
◦ Glucose uptake from blood to cells usually mediated by insulin and transporters
Liver is central site for carbohydrate metabolism
5. Blood glucose homeostasis.
Several cell types prefer glucose as energy source (eg., CNS)
80-100 mg/dl is normal range of blood glucose in non-ruminant animals
45-65 mg/dl is normal range of blood glucose in ruminant animals
Uses of glucose:
Energy source for cells
Muscle glycogen
6. Fates of glucose.
Fed state
◦ Storage as glycogen
Liver
Skeletal muscle
◦ Storage as lipids
Adipose tissue
Fasted state
◦ Metabolized for energy
◦ New glucose synthesized
7. Describe about glucose metabolism.
https://portlandpress.com/essaysbiochem/article/64/4/607/226177/Metabolism
Four major metabolic pathways:
Immediate source of energy
Pentose phosphate pathway
Glycogen synthesis in liver/muscle
Precursor for triacylglycerol synthesis
Energy status (ATP) of body regulates which pathway gets energy
8. Absorbed glucose:
1st Priority: glycogen storage
◦ Stored in muscle and liver
2nd Priority: provide energy
◦ Oxidized to ATP
3rd Priority: stored as fat
◦ Only excess glucose
◦ Stored as triglycerides in adipose
9. Describe about glucose ultilization.
•Adipose--energy stores
•Glycogen--energy stores
•Glycolysis--pyruvate
•Pentose phosphate pathway--ribose-5-phosphate
10. Describe about glycolysis.
Sequence of reactions that converts glucose into pyruvate
Relatively small amount of energy produced
Glycolysis reactions occur in cytoplasm
Glucose → 2 Pyruvate
-to Lactate (anaerobic)
-to Acetyl-CoA (TCA cycle)
Glucose(6C) + 2 ADP + 2 Pi
-to 2 Pyruvate(3C) + 2 ATP + 2 H2O
11. Describe about anaerobic metabolism of pyruvate to lactate.
a. Conversion to lactate (anaerobic)
Problem:
◦ During glycolysis, NADH(high energy molecule) is formed from NAD+
◦ Without O2 , NADH cannot be oxidized to NAD+
◦ No more NAD+
All converted to NADH
◦ Without NAD+ , glycolysis stops
Solution:
◦ Turn NADH back to NAD+ by making lactate (lactic acid)
ATP yield
◦ Two ATPs (net) are produced during the anaerobic breakdown of one glucose
The 2 NADHs are used to reduce 2 pyruvate to 2 lactate
◦ Reaction is fast and doesn’t require oxygen
Lactate can be transported by blood to liver and used in gluconeogenesis
Cori cycle: Lactate to pyruvate
b. Conversion to alanine (amino acid) i.e convert pyruvate to alanine and export to blood
Cahill/glucose alanine cycle: Transfer aa from muscle cell to hepatocytes in liver cell
c. Entry into the TCA cycle (Tricarboxylic acid cycle) via pyruvate dehydrogenase (PDH) pathway
Prepares pyruvate to enter the TCA cycle
-Produce CO2 and Acetyl CoA (convert to fats) as result
Aerobic
TCA: Acetyl-CoA to CO2
Regulation of PDH
12. Cori cycle & TCA cycle.
Cori: Lactate to pyruvate
Lactic acid cycle
Anaerobic
Involved liver, kidney, muscles, RBC
TCA : In aerobic conditions TCA cycle links pyruvate to oxidative phosphorylation
Occurs in mitochondria
Generates 90% of energy obtained from feed (carbohydrates, protein and fat metabolism)
Oxidize acetyl-CoA to CO2 and capture potential energy as NADH+&H+ (or FADH2) and some ATP
13. Oxidative phosphorylation & Electron transport system
Requires coenzymes (NAD and FADH) as H+ carriers and consumes oxygen
Key reactions take place in the electron transport system (ETS)
◦ Cytochromes of the ETS pass H2 ’s to oxygen, forming water
Oxidation & Reduction
Oxidation
Oxidation of nutrients releases stored energy
◦ Feed donates H+
◦ H+’s transferred to co-enzymes
NAD+ + 2H+ + 2e-= NADH + H+
FAD + 2H+ + 2e-= FADH2
Electron Transport
• From each molecule of glucose entering glycolysis:
1. From glycolysis: 2 NADH
2. From the TCA preparation step (pyruvate to acetyl-CoA): 2 NADH
3. From TCA cycle (TCA) : 6 NADH and 2 FADH2
TOTAL: 10 NADH + 2 FADH2
Electron transport chain
NADH + H+ and FADH2 enter ETC
◦ Travel through complexes I – IV
H+ flow through ETC and eventually attach to O2 forming water
NADH + H+ =3 ATP
FADH2= 2 ATP
Total ATP from glucose
Anaerobic glycolysis : 2 ATP + 2 NADH
Aerobic metabolism : glycolysis + TCA
30 ATP from 1 glucose molecule
Energy storage:
Energy from excess carbohydrates (glucose) stored as lipids in adipose tissue
Acetyl-CoA (from TCA cycle) shunted to fatty acid synthesis in times of energy excess
◦ Determined by ATP:ADP ratios
High ATP, acetyl-CoA goes to fatty acid synthesis
Low ATP, acetyl CoA enters TCA cycle to generate MORE ATP
14. Pentose phosphate pathway:
Secondary metabolism of glucose
◦ Produces NADPH
Similar to NADH
Required for fatty acid synthesis
◦ Generates essential pentoses
Ribose
Used for synthesis of nucleic acids
15. Describe about glycogenesis.
Liver
◦ 7–10% of wet weight
◦ Use glycogen to export glucose to the bloodstream when blood sugar is low
◦ Glycogen stores are depleted after approximately 24 hrs of fasting (in humans)
◦ De novo synthesis of glucose for glycogen
Skeletal muscle
◦ 1% of wet weight
◦ Use glycogen (i.e., glucose) for energy only (no export of glucose to blood)
◦ Use already-made glucose for synthesis of glycogen
Fasting situation:
Where does required glucose come from?
A. Glycogenolysis
Breakdown or mobilization of glycogen stored by glucagon
Glucagon - hormone secreted by pancreas during timesof fasting
B. Lipolysis
Mobilization of fat stores stimulated by glucagon and epinephrine
Triglyceride = glycerol + 3 free fatty acids
Glycerol can be used as a glucose precursor
C. Proteolysis
The breakdown of muscle protein with release of amino acids
Alanine can be used as a glucose precursor
16. Describe about gluconeogenesis.
Necessary process
◦ Glucose is an important fuel
- Central nervous system
- Red blood cells
Not simply a reversal of glycolysis
Insulin and glucagon are primary regulators
17. Carbohydrate metabolism/utilization tissue specificity
A. Muscle – cardiac and skeletal
◦ Oxidize glucose/produce and store glycogen (fed)
◦ Breakdown glycogen (fasted state)
◦ Shift to other fuels in fasting state (fatty acids)
B. Adipose and liver
◦ Glucose to acetyl CoA
◦ Glucose to glycerol for triglyceride synthesis
◦ Liver releases glucose for other tissues
C. Nervous system
◦ Always use glucose except during extreme fasts
D. Reproductive tract/mammary
◦ Glucose required by fetus
◦ Lactose to major milk carbohydrate
E. Red blood cells
◦ No mitochondria
◦ Oxidize glucose to lactate
◦ Lactate returned to liver for Gluconeogenesis
SUMMARY:
Glycolysis breakdown glucose(carbohydrates), beta oxidation of fats & amino acid catabolism produce pyruvate then converted to acetyl-CoA finally the TCA/Kreb's cycle oxidizes all acetyl-CoA to CO2.
Breaking of 6 carbon molecule (glucose) into 2 3 carbon molecules.
Transfer of 2 electrons to coenzyme NAD.
Capture of energy in ATP.
Through a series of redox, the electron transport chain performs 2 basic functions :
a. accepting electrons from an electron donor & transferring them to an electron acceptor
b.conserving for ATP synthesis some of energy released during electron transfer
Most microorganisms, like most animals, can obtain energy from lipids:
a. fats are hydrolyzed to glycerol & 3 fatty acids
b. glycerol is metabolized by glycolysis
c. fatty acids are broken down into 2 carbon pieces by beta-oxidation
Proteins can be metabolized for energy
a. they are first hydrolyzed into individual amino acids by proteolytic enzymes
b. amino acids are deaminated
These molecules enter glycolysis, fermentation or Kreb's cycle.
______
1. ATP powers cellular work by coupling exergonic reactions to endergonic reactions.
A cell does three main kinds of work
◦ Chemical
◦ Transport
◦ Mechanical
To do work, cells manage energy resources by energy coupling, the use of an exergonic process to drive an endergonic one
Most energy coupling in cells is mediated by ATP
#exergonic: from catabolism, energy-releasing
#endergonic: for cellular work, energy-consuming
2. Describe about Structure and hydrolysis of ATP.
ATP (adenosine triphosphate) is the cell’s energy shuttle
ATP is composed of ribose (a sugar), adenine (a nitrogenous base), and three phosphate groups
3. Describe about Regeneration of ATP.
ATP is a renewable resource that is regenerated by addition of a phosphate group to adenosine diphosphate (ADP)
The energy to phosphorylate ADP comes from catabolic reactions in the cell
The ATP cycle is a revolving door through which energy passes during its transfer from catabolic to anabolic pathways
4. Describe about Structure and classification of lipids.
Lipids can be divided into five categories, on the basis of lipid function
a. Energy-storage lipids (triacylglycerols)
b. Membrane lipids (e.g. phospholipids)
c. Emulsification lipids (bile acids)
d. Messenger lipids (e.g. steroid hormones)
e. Protective-coating lipids (biological waxes)
5. Fatty acids metabolism
Catabolism of fatty acids
◦ produced acetyl-CoA
◦ location: mitochondria
Anabolism of fatty acids
◦ requires malonyl-CoA and acetyl-CoA
◦ location: cytosol in animals, chloroplast in plants
6. Fatty acids synthesis
Glycolysis
◦ Cytoplasmic
PDH (pyruvate dehydrogenase)
◦ Mitochondrial
FA synthesis
◦ cytoplasmic
◦ Kreb cycle
moves AcCoA to cytoplasm
produces 50% NADPH via malic enzyme
Pyruvate malate cycle
7. Lipid biosynthesis
Lipids are the synthesized form fatty acid and glycerol.
Glycerol is derived from dihydroxyacetone phosphate, and fatty acids are built from acetyl CoA.
Lipases hydrolyze lipids into glycerol and fatty acids.
Fatty acids and other hydrocarbons are catabolized by beta oxidation. Glycerol to Dihydroxyacetone phosphate to glycolysis to acetyl-CoA to Kreb's cycle.
Beta oxidation produces two carbon units that are linked to CoA to make acetyl-CoA.
#Beta oxidation of fatty acids:
a. In reaction 1, oxidation. H atoms are removed from alpha & beta carbons. A trans C=C bond is formed. FAD is reduced to FADH2.
b. In reaction 2, hydration. Adds water across the trans C=C bond. A -OH grp froms on beta carbon.
c. In reaction 3, 2nd oxidation. -OH grp is oxidized. A keto grp is formed on beta carbon.
d. In reaction 4, acetyl-CoA is cleaved by splitting bond btwn alpha & beta carbon to form a shortened fatty acyl CoA that repeats steps 1-4 of beta oxidation.
#Beta oxidation of myristic (C14) acid:
a. reaction 1, oxidation (dehydrogenation)
b. reaction 2, hydration
c. reaction 3, oxidation (dehydrogentaion)
d. reaction 4, cleavage. 6 cycles. 7 acetyl-CoA.
#Beta oxidation cycles([Carbon/2]-1):
length of fatty acids:
determines no. of oxidations & total no. of acetyl-CoA grps(Carbon/2)
Catabolic products can be further broken down in glycolysis and the Krebs cycle.
#Fat mobilization:
Breaks down triacylglycerols in adipose tissue to fatty acids & glycerol. Fatty acids are hydrolyzed initially from C1 or C3 of the fat.
Triaglycerols+3H2O to Glycerol+3 Fatty acids
#Fatty acid activation:
Complex but regulates degradation & synthesis of fatty acids.
#Metabolic Fates of Acetyl-CoA:
https://www.vma.is/static/files/raungreinar/efn413/Namsefni/kaflar25_6og7.PDF
8. Describe about Ketogenesis.
#fatty acid oxidation results in acetyl CoA
#liver mitochondria can convert this acetyl CoA into ketone bodies
#body fat breaks down to meet energy needs
Ketogenesis = make ketone bodies from acetyl-CoA.
Ketone bodies = Acetoacetate, D-β-Hydroxybutyrate and acetone.
◦ Ketone bodies (except acetone) are released by the liver, transported in blood to and used as fuel for peripheral tissues. They can reconverted to acetyl CoA, which can be oxidized by TCA cycle.
◦ The brain metabolizes ketone bodies if starved of glucose.
#Importance of ketone bodies:
a. can be utilized by brain to meet energy requirements during fasting periods
b. they are soluble in aqueoous solution, so don't need to be transported in lipoproteins or carried by albumin
c. produced in liver when there are high levels of Acetyl CoA which exceed the oxidative capacity of liver
d. used in proportion to their concentration in blood
Occurs in liver mitochondria, used as fuel in muscle and brain.
Starvation or diabetes lead to ketoacidosis.
Ketoacidosis (also called ketosis) = build up of acetoacetate drives decarboxylation to acetone. Breath smells of acetone (sweet). Lack of β-Hydroxybutyrate in urine.
Ketone bodies can be converted back to acetyl-CoA:
β-Hydroxybutyrate → acetoacetate → acetoacetyl-CoA → 2x acetyl-CoA.
#Ketosis occurs in diabetes, diets high in fat and starvation as ketone bodies accumulate. When acidic ketone bodies lowers blood pH below 7.4 (acidosis).
SUMMARY:
a. lipids stored as adipose tissue - insulation, support vital organs, generate heat, stored as energy reserve-lipoprotein in blood.
b. lipid ingestion - digestion & absorption-lipoprotein in blood.
c. lipids in blood as lipoproteins - excreted in faeces, synthesized from carbohydrate & protein, oxidize for energy, convert to brain & nerve tissue.
9. Describe about Lipoproteins.
“Proteins covalently linked to lipid found in the blood plasma”
Plasma lipoproteins transport lipid through the bloodstream. On the basis of density, lipoproteins are classified into four major classes:
Chylomicrons: Large lipoproteins of extremely low density; transport dietary triglycerols and cholesteryl esters from intestine to the tissues (muscle/ adipose)
VLDL (0.95-1.006 g/cc) : synthesized in the liver ; transport lipids to tissues; coverted to LDL with depletion of triglycerol, apoproteins and phospholipids
LDL (1.006 - 1.063 g/cc): carry cholesterol to tissues; engulfed by cells after binding to LDL receptors
HDL (1.063 - 1.210 g/cc ): produced in liver; scavenge cholesterol from cell membrane as cholesteryl ester which is transported to liver from where the excess cholesterol is disposed of as bile acids
#HIGH DENSITY LIPOPROTEINS (HDL)
More protein; less cholesterol (5% triglyceride, 20% cholesterol, 30% phosphogyceride, 45-50% protein)
Transports cholesterol from cells back to the liver
#LOW DENSITY LIPOPROTEINS (LDL)
Less protein, more cholesterol (10% triglyceride, 45% cholesterol, 22% phosphoglyceride, 25% protein)
Transports cholesterol from the liver to cells
10. Describe about Lipogenesis & lipolysis
Fatty acid may be converted to triacylglycerol, degradated to generate energy, or utilized in membrane synthesis
When serum glucose level is high after meal, insuline promotes triacylglycerol synthesis by facilitating the transport of glucose into adipocytes - lipogenesis
Adiposites can not synthesize triacylglycerol when glucose level is low (between meal), when several hormones stimulate the hydrolysis of triacyl-glycerol within adipose tissue to form glycerol and fatty acids – lipolysis.
11. Describe about Lipid metabolism in fat cells.
a. Fed state
Insulin :
i. stimulates Lipoprotein lipase (LPL)
◦ increased uptake of FA from chylomicrons and VLDL
ii. stimulates glycolysis
◦ increased glycerol phosphate synthesis
◦ increases esterification
induces Hormone Sensitive Lipase-cholesteryl ester hydrolase
◦ inactivates HSL
net effect: TG storage
b. Starved/Exercising state
Glucagon, epinephrine
activates adenylate cyclase
◦ increases cAMP
◦ activates protein kinase A
◦ activates HSL
net effect: TG mobilization and increased FFA
12. Hepatic ketone body synthesis
Occurs during starvation or prolonged exercise
◦ result of elevated FFA
- high HSL activity
◦ High FFA exceeds liver energy needs
◦ KB are partially oxidized FA
13. Ultilization of ketone bodies by extrahepatic tissues
When [KB] = 1-3mM, then KB oxidation takes place
◦ 3 days starvation [KB]=3mM
◦ 3 weeks starvation [KB]=7mM
◦ brain succ-CoA-AcAc-CoA transferase induced when [KB]=2-3mM
a. Allows the brain to utilize KB as energy source
b. Markedly reduces
- glucose needs
- protein catabolism for gluconeogenesis
______
1. Describe about Protein metabolism.
Proteins are not a primary source of energy and are not stored
- Yet a certain amount of protein catabolism occurs in the body each day as proteins from cells are broken down into amino acids
- Some amino acids are converted into other amino acids, peptide bonds are re-formed, and new proteins are synthesized as part of the recycling process
Anabolism:
The formation of peptide bonds between amino acids to produce new proteins, is carried out on the ribosomes of almost every cell in the body, directed by the cells’ DNA and RNA.
In protein synthesis, transamination refers to the transfer of an amino group (NH2) from an amino acid to pyruvic acid or to an another acid in the Krebs cycle to form an amino acid; nonessential Aa. An essential Aa which cannot be synthesized in the body must present from diet.
Once the appropriate essential and nonessential Aa are present in cells, protein synthesis occurs rapidly
Catabolism:
deamination refers to the removal of an amino group leaving the carbons of a carboxylic acid to be used to make ATP
Aa are oxidized via Kreb cycle after deamination. Ammonia resulting from deamination is converted into urea in liver, passed into blood and excreted in urine.
Aa may be converted into glucose (gluconeogenesis), fatty acid or ketone bodies
2. Nonessential amino acids
Alanine and aspartate biosynthesis
Those that can be produced by human.
Pathways are relatively straightforward.
pyruvate + glutamate -<alanine aminotransferase>-alanine + alpha-ketoglutarate
oxaloacetate + glutamate -<aspartate aminotransferase>-aspartate +alpha-ketoglutarate
Some pathways are more complex, like the one for serine.
Serine biosynthesis
3-phosphoglycerate>oxidation-reduction(NAD+ to NADH+ & H+)>3-phospho- hydroxy-pyruvate >transamination(glutamate to alpha-ketoglutarate)>3-phospho- serine>hydrolysis(water to Pi)>serine
Glycine biosynthesis
Glycine is synthesized from serine.
It uses an unusual process,a one carbon transfer.
Tetrahydrofolate (FH4 ) is an essential cofactor for this reaction.
Serine+Tetrahydrofolate --Glycine+N5 ,N10-Methylene- tetrahydrofolate
3. Essential amino acids
Produced by plants and bacteria.
Example :
Synthesis of phenylalanine, tyrosine and tryptophan.
They share two to three common steps.
Production of intermediates
*Major metabolic pathways of aa
4. Protein turnover
In animals, about 75% of all amino acids are used for the production of protein.
Because of the constant degradation of cellular structure, proteins in the body are constantly being replaced - protein turnover.
Old proteins are constantly degraded. New proteins have to be synthesized for tissue growth and cell repairing.
5. Amino acid catabolism
• Amino acids cannot be stored.
• If there is an excess of amino acids or a lack of other energy sources, the body will use them for energy production.
• Amino acid degradation requires the removal of the amino group as ammonium.
• Ammonium must then be disposed of as it is toxic to the body.
Amino acids are only used as fuel when:
• Too much protein is ingested
• Normal recycling of protein
• Starvation/diabetes.
Catabolic pathways
• Each amino acid has a unique pathway.
• All are converted to mainstream metabolites.
Catabolism of amino acids starts with deamination.
• After losing the amino group the rest of the carbon skeleton can usually enter TCA cycle as intermediate molecules for energy production.
6. Removal of amino group
Transamination reaction
- Aminotransferase moves the amino group to alpha-Keto acid to form another amino acid.
- The amino group receiver is usually alpha- ketoglutarate (+ alanine) to produce glutamate (+ pyruvate to citric acid cycle). <Alanine aminotransferase>
- diagnose heart and liver damage using transaminase enzymes
Oxidative deamination
- Removal of the amino group from glutamate producing an ammonium ion (to urea cycle). (+Alpha-ketoglutarate) <glutamate dehydrogenase>
#NH3 and NH4+ produced from deamination are both toxic, even in small amount .
NH3 and NH4+ have to be transformed into organic molecules or to be removed from the body.
NH4+ can either used for the biosynthesis of glutamate (NH4+ + α-ketoglutarate) or to enter urea cycle for excretion.
#non-oxidative deamination
7. Elimination of ammonium ion
Amino acid detoxification
NH4+ is produced from amino acid catabolism is toxic and must be eliminated.
NH4+ is eliminated through the urea cycle that occurs in the liver.
The urea cycle
◦ Occurs in the liver.
◦ Results in the formation of urea.
◦ Urea is eliminated by excretion (urine).
8. Urea cycle
Urea cycle is a five-step pathway carried out by liver cells.
The strategy is to synthesize arginine that is then hydrolyzed to release urea and L-ornithine.
No alternate pathway for NH4 + elimination.
Some genetic disorders will affect
A. arginase
B. carbamoyl phosphate synthase
C. ornithine transcarbamoylase
As one important group of nutrients, the main functions of proteins and amino acids are for making new cellular structure, making hormones and enzymes.
A small portion of amino acids serves as precursors of important biomolecules such as porphyrins, nucleic acids, nucleotide bases and biogenic amines.
9. Amino acids as precursors of other biomolecules
Porphyrins
Important part of all pigment proteins (heme, chlorophyll, cytochromes) as prosthetic groups:
Porphyrin = combination of succinyl CoA and glycine.
Heme = Fe + porphyrin.
chlorophyll = Mg + porphyrin.
10. Porphyrin biosynthesis
The first step is the condensation of glycine and succinyl CoA to alpha-amino-beta- ketoadipate to produce 5-aminolevulinate (ALA).
Next, two molecules of ALA are used to produce porphobilinogen.
Four porphobilinogen molecules are then condensed to produce protophorphyrin IX.
Finally, for heme, an Fe2+ is inserted. <ferrochelatase>
11. Biogenic amine
Histamine, serotonin, melatonin, dopamine, norepinephrine etc. A group of biologically active molecules with small size.
Most of them are the products of decarboxylation of amino acids.
Histamine - decarboxylated form of histidine;
GABA, a neurotransmitter is from glutamate;
Serotonin, melatonin are the derivatives of tryptophan…
Dopamine and epinephrine are converted from tyrosine.
12. Purine and pyrimidine nucleotides
Aspartate, glycine and glutamine are precursors for making purines and pyrimidines.
13. Integration of metabolism
A. Interconnection of pathways
B. Metabolic profile of organs
C. Food intake, starvation and obesity
D. Fuel choice during exercise
E. Ethanol alters energy metabolism
F. Hormonal regulation of metabolism
https://www.youtube.com/results?search_query=Integration+of+Metabolism+animation
https://www.youtube.com/watch?v=Cj0ddEk1ho8
https://www.slideshare.net/prabeshrajjk/lecture-21-40727540
14. Connection of pathway
A. ATP is the universal currency of energy
B. ATP is generated by oxidation of glucose, fatty acids, and amino acids ; common intermediate -> acetyl CoA ; electron carrier -> NADH and FADH2
C. NADPH is major electron donor in reductive biosynthesis
D. Biomolecules are constructed from a small set of building blocks
E. Synthesis and degradation pathways almost always separated -> Compartmentation
#Cytosol: Glycolysis, Pentose phosphate pathway, Fatty acid synthesis
#Mitochondrial matrix: Citric acid cycle, oxidative phosphorylation, beta-oxidation of fatty acids, ketone body formation
#Interplay of both compartments: Gluconeogenesis, urea synthesis
15. Metabolic profile
A. Brain
• transport ions to maintain membrane potential; integrates inputs from body and surroundings; send signals to other organs
• Glucose is fuel for human brain
-> consumes 120g/day
-> 60-70 % of utilization of glucose
• In starvation -> ketone bodies can replace glucose
Electrogenic transport by Na+K+ATPase
B. Muscle
ATP for mechanical work
ATP produced by glycolysis for rapid contraction
Major fuels are glucose, fatty acids, and ketone bodies
-> has a large storage of glycogen -> about ¾ of all glycogen stored in muscles
-> glucose is preferred fuel for burst of activity -> production of lactate (anaerobe)
-> fatty acid major fuel in resting muscles and in heart muscle (aerobe)
Phosphocreatine->creatine--bursts of heavy activity
Short-duration & prolonged duration exercise
C. Adiposite tissue
Synthesize, store, and mobilize triacylglycerols
Triacylglycerols are stored in tissue
-> enormous reservoir of metabolic fuel
-> needs glucose to synthesis TAG;
-> glucose level determines if fatty acids are released into blood
D. Liver /glucose
Essential for providing fuel to brain, muscle, other organs
-> most compounds absorpt by diet
-> pass through liver
-> regulates metabolites in blood
E. Liver /aa
Alpha-Ketoacids (derived from amino acid degradation)
-> liver’s own fuel
#lymphatic system
Carries lipids from intestine to liver
#small intestine
Absorbs nutrients from diets, and moves them into blood or lymphatic system
#portal vein
Carries nutrients from intestine to liver
#pancreas
Secretes insulin and glucagon in response to change blood glucose concentration
16. Food intake and starvation
Normal Starved-Fed Cycle:
-> Major goal is to maintain blood glucose level (60-90mg/100ml)
#Blood glucose
A. Postabsorptive state -> after a meal
Glucose + Amino acids -> transport from intestine to blood
Dietary lipids transported -> lymphatic system -> blood
Glucose stimulates -> secretion of insulin
Insulin:
-> stimulates storage of fuels and synthesis of proteins
-> high level -> glucose enters muscle + adipose tissue (synthesis of TAG)
-> stimulates glycogen synthesis in muscle + liver
-> suppresses gluconeogenesis by the liver
-> accelerates glycolysis in liver -> increases synthesis of fatty acids
-> accelerates uptake of blood glucose into liver -> glucose 6-phosphate more rapidly formed than level of blood glucose rises -> built up of glycogen stores
B. Early fasting state -> during the night
Blood-glucose level drops after several hours after the meal
-> decrease in insulin secretion
-> rise in glucagon secretion
Low blood-glucose level -> stimulates glucagon secretion of α-cells of the pancreas
Glucagon:
-> signals starved state
-> mobilizes glycogen stores (break down)
-> inhibits glycogen synthesis
-> main target organ is liver
-> inhibits fatty acid synthesis
-> stimulates gluconeogenesis in liver
-> large amount of glucose in liver released to blood stream -> maintain blood- glucose level
Muscle + Liver use fatty acids as fuel when blood-glucose level drops
17. Prolonged Starvation
Well-fed 70 kg human -> fuel reserves about 161,000 kcal
-> energy needed for a 24 h period -> 1600 kcal - 6000 kcal
-> sufficient reserves for starvation up to 1 – 3 months
-> however glucose reserves are exhausted in 1 day
Even under starvation -> blood-glucose level must be above 40 mg/100 ml
First priority -> provide sufficient glucose to brain and other tissues that are dependent on it
Second priority
-> preserve protein
-> shift from utilization of glucose to utilization of fatty acids + ketone bodies
-> mobilization of TAG in adipose tissues + gluconeogenesis by liver
-> muscle shift from glucose to fatty acids as fuel
After 3 days of starvation -> liver forms large amounts of ketone bodies (shortage of oxaloacetate) -> released into blood -> brain and heart start to use ketone bodies as fuel
After several weeks of starvation
-> ketone bodies major fuel of brain. After depletion of TAG stores -> proteins degradation accelerates -> death due to loss of heart, liver, and kidney function
SUMMARY:
http://watcut.uwaterloo.ca/webnotes/PDF/MetabolismNotes.pdf
#hyperthyroidism: abnormal metabolism
https://www.healthline.com/health/hyperthyroidism#lifestyle-remedies
Lect 8
Enzyme and hormone
1. Define metabolic pathway.
A metabolic pathway begins with a specific molecule and ends with a product
Each step is catalyzed by a specific enzyme
2. Define catalyst, enzyme and hydrolysis.
A catalyst is a chemical agent that speeds up a reaction without being consumed by the reaction
https://www.youtube.com/watch?v=m_9bpZep1QM
An enzyme is a catalytic protein
Hydrolysis of sucrose by the enzyme sucrase is an example of an enzyme-catalyzed reaction
Sucrose+H2O-<sucrase>-glucose+fructose
3. Define cofactors and coenzymes.
Cofactors are nonprotein enzyme helpers. Cofactors may be inorganic (such as a metal in ionic form) or organic.
An organic cofactor is called a coenzyme.
Coenzymes include vitamins.
https://www.youtube.com/watch?v=LK5HzcAOmyA
4. Regulation of enzyme activity helps control metabolism.
Negative feedback
Positive feedback
5. Special localization of enzymes within cell.
Structures within the cell help bring order to metabolic pathways
Some enzymes act as structural components of membranes
In eukaryotic cells, some enzymes reside in specific organelles; for example, enzymes for cellular respiration are located in mitochondria
5. Classes of enzymes.
In 1964 the International Union of Biochemistry established an Enzyme
Commission to develop a nomenclature for enzymes.
Reactions were divided into six major groups numbered 1 through 6.
(1) oxidoreductases, which are involved in redox: lactate dehydrogenase ; (2) transferases, which transfer a chemical group from one substance to another: nucleoside monophosphate kinase/nmp kinase ; (3) hydrolases, which cleave the substrate by uptake of a water molecule (hydrolysis): chymotrypsin ; (4) lyases, which form double bonds by adding or removing a chemical group: fumarase ; (5) isomerases, which transfer a group within a molecule to form an isomer (isomerization):triode phosphate isomerase ; and (6) ligases, or synthetases, which couple the formation of various chemical bonds to the breakdown of a pyrophosphate bond in adenosine triphosphate or a similar nucleotide (ligation):aminoacyl-tRNA-synthetase.
6. Enzyme component.
Most enzymes are holoenzymes (active functional enzyme), consisting of a protein portion (inactive apoenzymes) and a nonprotein portion (activator cofactor).
The cofactor can be a metal ion (iron, copper, magnesium, manganese, zinc, calcium, or cobalt) or a complex organic molecule known as a coenzyme (NAD+, NADP+, FMN, FAD, or coenzyme A).
7. Mechanism of enzymatic action.
When an enzyme and substrate combine, the substrate is transformed into the product, and the enzyme is recovered.
Enzymes are characterized by specificity, which is a function of their active sites.
8. Factors influencing enzymatic activity.
https://www.youtube.com/watch?v=rlH1ym916Fo
At high temperatures, enzymes undergo denaturation and lose their catalytic properties; at low temperatures, the reaction rate decreases.
The pH at which enzymatic activity is maximal is known as the optimum pH.
Within limits, enzymatic activity increases as substrate concentration increases.
Competitive inhibitors compete with the normal substrate for the active site of the enzyme.
Noncompetitive inhibitors act on other parts of the apoenzyme or on the cofactor and decrease the enzyme’s ability to combine with the normal substrate.
9. Define hormones.
https://www.youtube.com/results?search_query=Hormones+ANIMATION+
Hormones – organic biologically active compounds of different chemical nature that are produced by the endocrine glands, enter directly into blood and accomplish humoral regulation of the metabolism of compounds and functions on the organism level.
Pineal gland, hypothalamus, pituitary gland, thyroid gland, parathyroid gland, thymus, adrenal glands (atop kidney), pancreas, ovary, testis
• Hormones are chemical messengers.
• Hormones have a variety of structures including proteins, steroids, modified amino acids and fatty acids.
• They are secreted directly into the blood by endocrine glands in response to various stimuli
o This is because the glands do not have ducts
• Hormones are transported using the blood stream
10. Classification of hormones.
A. Proteins: hormones of anterior pituitary (except ACTH), insulin, parathyroid hormone.
B. Peptides: ACTH, calcitonin, glucagon, vasopressin, oxytocin, hormones of hypothalamus (releasing factors and statins).
C. Derivatives of amino acids: catecholamins (epinephrine and norepinephrine), thyroxin, triiodthyronin, hormones of epiphysis.
D. Steroid (derivatives of cholesterol): hormones of the cortex of epinephrine lands, sex hormones.
E. Derivatives of polyunsaturated fatty (arachidonic) acids: prostaglandins.
11. Functions.
12. Characteristics.
Hormones are secreted in minute amounts into the interstitial space.
Hormones eventually enter the circulatory system and arrive at specific target tissues.
Hormones control the rates of many activities in the body.
The rate at which each hormone is secreted is controlled by a negative feedback mechanism.
Three major patterns of regulation:
◦ Non-hormone substance (e.g. insulin)
◦ Stimulation by the nervous system (e.g. epinephrine)
◦ Hormone from another endocrine tissue (e.g. TRH, TSH)
13. Transport and distribution in body.
Hormones are dissolved in the blood plasma and transported in free form or bound to a protein carrier.
As a result, hormones can be distributed throughout the body relatively quickly.
Hormones diffuse from the capillary to the interstitial space.
Lipid-soluble hormones diffuse through the walls of all capillaries.
Water-soluble hormones must pass through pores.
14. Interaction of hormones with their target tissue.
Hormones only interact with cells that have binding sites that are specific for the particular hormone.
Lect 9
Vitamin and mineral
1. Define vitamins.
Complex substances that regulate body processes
Coenzymes (partners) with enzymes in reactions
No calories, thus no energy
2. Determine the categories of vitamins.
• Water-soluble :
Dissolve in water carried in bloodstream, not stored
A, D, E, K
• Fat-soluble :
Dissolve in fat can be stored
C and B-complex vitamins
A. Vitamin A
Functions:
◦ Normal vision
◦ Protects from infections
◦ Regulates immune system
◦ Antioxidant (carotenoids)
Sources:
◦ Liver
◦ Fish oil
◦ Eggs
◦ Fortified milk or other foods
◦ Red, yellow, orange, and dark green veggies (carotenoids)
B. Vitamin D
Functions:
◦ Promotes absorption of calcium and phosphorus
◦ Helps deposit those in bones/teeth
◦ Regulates cell growth
◦ Plays role in immunity
Sources:
◦ Sunlight (10 – 15 mins 2x a week)
◦ Salmon
◦ Milk
◦ Orange juice (fortified)
◦ Fortified cereals
C. Vitamin E
Functions:
◦ Antioxidant, may lower risk for heart disease and stroke中风, some types of cancers
◦ Protects fatty acids and vitamin A
Sources:
◦ Vegetable oils
◦ Foods made from oil (salad dressing, margarine)
◦ Nuts
◦ Seeds
◦ Wheat germ
◦ Green, leafy veggies
D. Vitamin K
Functions:
◦ Helps blood clot
◦ Helps body make some other proteins
Sources:
◦ Body can produce on its own (from bacteria in intestines)
◦ Green, leafy veggies
◦ Some fruits, other veggies, and nuts
E. Thiamine B1
Functions:
◦ Helps produce energy from carbs (carbohydrate)
Sources:
◦ Whole-grain and enriched grain products
◦ Pork
◦ Liver
F. Riboflavin B2
Functions:
◦ Produce energy
◦ Changes tryptophan (amino acid) into niacin
Sources:
◦ Liver
◦ Yogurt and milk
◦ Enriched grains
◦ Eggs
◦ Green, leafy veggies
G. Niacin B3
Functions:
◦ Helps body use sugars/fatty acids
◦ Helps enzymes function normally
◦ Produces energy
Sources:
◦ Foods high in protein typically (poultry, fish, beef, peanut butter, legumes)
◦ Enriched and fortified grains
H. Pyridoxine B6
Functions:
◦ Helps body make non -essential amino acids
◦ Helps turn tryptophan into niacin and serotonin
◦ Help produce body chemicals (insulin, hemoglobin, etc)
Sources:
◦ Chicken
◦ Fish
◦ Pork
◦ Liver
◦ Whole grains
◦ Nuts
◦ Legumes
I. Folate/Folic acid
Functions:
◦ Produces DNA and RNA, making new body cells
◦ Works with vitamin B12 to form hemoglobin
◦ May protect against heart disease
◦ Lowers risk of neural tube defects in babies
◦ Controls plasma homocystine levels (related to heart disease)
Sources:
◦ Fortified and enriched grains and breakfast cereals
◦ Orange juice
◦ Legumes
◦ Green, leafy veggies
◦ Peanuts
◦ Avacados
J. Cobalamin B12
Functions:
◦ Works with folate to make RBC’s
◦ In many body chemicals and cells
◦ Helps body use fatty acids/amino acids
Sources:
◦ Animal products
◦ Meat
◦ Fish
◦ Poultry
◦ Eggs
◦ Milk, other dairy
K. Vitamin C
Functions:
◦ Helps produce collagen (connective tissue in bones, muscles, etc)
◦ Keeps capillary walls, blood vessels firm
◦ Helps body absorb iron and folate
◦ Healthy gums
◦ Heals cuts and wounds
◦ Protects from infection, boosts immunity
◦ Antioxidant
Sources:
◦ Citrus fruits
◦ Other fruits, veggies
3. Define minerals.
Regulate body processes
Give structure to things in the body
No calories (energy)
Cannot be destroyed by heat
4. Determine the categories of minerals.
A. Major minerals
◦ Calcium
Bone building
Muscle contraction
Heart rate
Nerve function
Helps blood clot
◦ Phosphorus
Generates energy
Regulate energy metabolism
Component of bones, teeth
Part of DNA, RNA (cell growth, repair)
Almost all foods, especially protein-rich foods, contain phosphorus
◦ Magnesium
Part of 300 enzymes (regulates body functions)
Maintains cells in nerves, muscles
Component of bones
Best sources are legumes, nuts, and whole grains
◦ Electrolytes (sodium, chloride, potassium)
Chloride:
◦ Fluid balance
◦ Digestion of food, transmits nerve impulses
Potassium
◦ Maintains blood pressure
◦ Nerve impulses and muscle contraction
Sodium
◦ Fluid balance
◦ Muscles relax, transmit nerve impulses
◦ Regulates blood pressure
Sources:
◦ Salt (sodium chloride)
◦ Fruits, veggies, milk, beans, fish, chicken, nuts (potassium)
B. Trace minerals
◦ Chromium
◦ Copper
◦ Flouride
◦ Iodine
◦ Manganese
◦ Selenium
◦ Zinc
◦ Iron
Part of hemoglobin, carries oxygen
Brain development
Healthy immune system
Sources:
- Animals (heme) vs. plants (non-heme)
- Better absorbed from heme
- Consume vitamin C with non-heme
- Fortified cereals, beans, eggs, etc.
4. Define the antioxidants.
Slow or prevent damage to body cells
May improve immune function and lower risk for infection and cancer
Carotenoids – beta carotene (familiar)
Vitamin C and Vitamin E
Found in colorful fruits/veggies and grains
SUMMARY
https://www.youtube.com/watch?v=j_hHKF-nXYI
https://www.youtube.com/watch?v=ISZLTJH5lYg
https://www.youtube.com/watch?v=7WnpSB14nDM
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