Which of the following statements about topoisomerases is FALSE?

Type I AND type II topoisomerases can both increase or decrease L.

In the reaction catalyzed by type I topoisomerases, the enzyme changes conformation to provide the energy required to change the linking number of the DNA.

Type I topoisomerases use a tyrosine side chain in their active site to catalyze a nucleophilic attack.

Type I topoisomerases do not use ATP in their reaction mechanism.

Type II topoisomerases can increase writhe because they use ATP in their reaction mechanism.

The sirtuins are a class of NAD-dependent deacetylases that are thought to play a role in the cellular response to nutritional status. Some sirtuins are involved in remodeling chromatin structure. A) How would you expect deacetylation of histones to affect the transcriptional activity of genes? B) Sirtuin 3 (Sirt3) deacetylates a specific lysine in the active site of acetyl-CoA synthetase, activating the enzyme. Why would this particular deacetylation reflect nutritional status? Remember, acetyl-CoA synthetase catalyzes the reaction: ATP + acetate + CoA <=> AMP + PPi + acetyl-CoA

Which of the following substances is secreted by sweat glands in response to breakdown of proteins and formation of ammonia? which of the following describe the function of the neuron? A.creates electrical impulses B.transmits sensory information C.stores potassium ions

Which of the following statements is a valid conclusion from the experiment above? A. Killed bacteria components can make live bacteria deadly B. Dead bacteria are more deadly than live bacteria C.Protein are dangerous to bacteria and kill them D.Protease enzyme causes live bacteria to become deadly

1. Fill in the table below concerning chromatin modification.

2. A moth census on Wooded Island counted 100 black (BB) moths, 40 gray (Bb) and 60 white (bb) moths. What are the genotypic frequencies? What are the allelic frequencies? Is the population in Hardy-Weinberg equilibrium?   

Ill Rate High

A variety of plants are used as folk medicine in the treatment of hypertension.
Laboratory analyses show that a purified extract from one of these plants decreases
production of aldosterone in an animal model.
Complete the sentences below to explain how this anti-hypertensive plant extract might
work. In each case indicate the enzyme, hormone or receptor targeted and explain how the
action of the extract on this target would result in reduced aldosterone production.
A. The purified extract inhibits…
(60-word limit)
B. The purified extract blocks…
(60-word limit)

TRUE or FALSE? Please explain each answer!

a) The more negative the ∆H value of a reaction the faster it is.

b) The more negative the ∆G value of a reaction the faster it is.

c) If you compare two reactions, the one with the lowest activation energy is faster (tricky!)

d) A catalyst is a substance that lowers the ∆G value of a reaction so it becomes more spontaneous.

e)Enzymes are proteins that lower the activation energies of reactions in the cell.

f) ATP hydrolysis is thermodynamically favorable but the reaction is slow in the absence of the enzyme specialized in catalyzing this reaction.

Considering the Metabolic pathways of Pseudomonas aeruginosa:

A. Briefly evaluate the metabolism of the organism. How do they make PMF, ATP and reducing power? Do they have a broad or a narrow metabolic capacity?

B. How would deleting the TCA cycle affect this organism?

C. What about a mutation in the quinol binding site of the bc1 complex (Complex III) so that it could not accept a quinol?

D. What about a mutation in the gene that encodes glyceraldehyde-3-P dehydrogenase (the enzyme that catalyzes the oxidation of G-3-P)?

The clinical symptoms of two forms of galactosemia show radically different severity.

1. Deficiency of galactokinase
2. Deficiency of UDP-glucose:galactose 1-phosphate uridylyltransferase

Although both types produce gastric discomfort after milk ingestion, deficiency of the transferase also leads to liver, kidney, spleen, and brain dysfunction and eventual death.

Explain, what products accumulate in the blood and tissues with each type of enzyme deficiency? (3 point)

List the symptoms for each type of deficiency. (3 point).

Explain which of these products is more toxic and why?

Question:

DNA polymerase III is the main DNA-synthesizing enzyme in bacteria. Describe how it carries out its role of elongating a strand of DNA.

Answer:

DNA pol III determines which free nucleotide triphosphate is complementary to the base being copied. DNA pol III catalyzes phosphodiester bond formation between the alpha phosphate of the incoming nucleotide triphosphate and the 3’ hydroxyl group of the last nucleotide added to the strand.

Can someone please explain this step by step in a dumbed down version? Thank you!

A protonated histidine residue in the active site of aspartate transcarbamoylase, ATCase, is thought to be important in stabilizing the transition state of the bound substrate.

A) Sketch a graph showing the pH dependence of the catalytic rate, assuming that this interaction is essential and dominates the pH-activity profile of the enzyme. Provide the biochemical basis for your graph.

B) The ATCase mechanism is known to proceed via an ordered mechanism. Draw a Cleland notation diagram showing how this reaction proceeds. Abbreviate the second substrate as CP. Two products are formed.  

Thank you!