学霸笔记

Lect 7  Microbial genetics 1. Genetic Material DNA & RNA DNA=deoxyribonucleic acid RNA=ribonucleic acid  Basic building blocks: Nucleotides Phosphate group Pentose sugar Nitrogenous base 2. Structure of DNA  Double stranded (double helix)   Chains of nucleotides   5’ to 3’ (strands are anti-parallel)   Complimentary base pairing  ◦ A-T ◦ G-C #Prokaryotic chromosome 3. DNA Replication  Semiconservative ◦ Replication fork  Single origin  Bidirectional  2 Leading strands  2 Lagging strands  Enzymes  Helicases  DNA polymerases 5’ to 3’  I for leading strand  II RNA primer  III for lagging strand  DNA ligase  DNA gyrase  DNA is unzipped by unwinding enzyme helicase  RNA primer join at the replication site  This primer gives signal to enzyme DNA polymerase to synthesize new DNA strand • One new DNA strand (Leading strand) is synthesized continuously in the 5’ 3’ direction  • In contrast, the lagging strand is synthesized...

  Tigers | Nonfiction Reading Test 2   Who would win in a fight, a lion or a tiger? Well, if size has anything to do with the matter, the tiger would win. That’s because tigers are the largest of all cat species. They grow up to eleven feet long and weigh as much as 670 lbs. This makes tigers the third largest land carnivore. The only larger land carnivores are polar bears and brown bears. Tigers are not only large, they are also fast. They can sprint as fast as 40 miles per hour for short distances and leap as far as 30 feet horizontally.   This makes for an extremely dangerous pounce. You might not think that such large, fast, and ferocious creatures need help to survive, but they do. The tiger is an endangered species. Despite all of the tiger’s strengths, the future of the species is uncertain. Tigers face a very high risk of extinction. It is estimated that at the start of the 20 th century, there were over 100,000 tige...

Lect 15 The Autonomic Nervous System 1. Describe about autonomic nervous system • The autonomic nervous system (ANS) operates via reflex arcs. • Regulate activity of smooth muscle, cardiac muscle & certain glands • Receives input from limbic system and other regions of the cerebrum • Operation of the ANS to maintain homeostasis, however, depends on a continual flow of sensory afferent input, from receptors in organs,  and efferent motor output to the same effector organs.  • Structurally, the ANS includes autonomic sensory neurons, integrating centers in the CNS, and autonomic motor neurons.  • Functionally, the ANS usually operates without conscious control. • The ANS is regulated by the hypothalamus and brain stem. ANS: • The output (efferent) part of the ANS is divided into two principal parts:   – the sympathetic division – the parasympathetic division – Organs that receive impulses from both sympathetic and parasympathetic fibers are said to have du...