1. Explain DNA replication. All the enzyme involved and the orientation of the strands as well.
2. What are okazaki fragments?
3. What is DNA ligase?
4. What is DNA polymerase III, DNA polymerase I, What is Primase? What is topoisomerase?

I need to calculate the turnover rate of an enzyme using a lineweaver-burk plot. Is there a specific equation that should be used to calculate Kcat? I have been unable to find a straightforward answer on how to calculate Kcat!

Hello. Question:

I have absorption data collected from 5 samples of the same enzyme at different concentration. The data is collected over the interval of 3 minutes. How can I convert this into catalytic velocity?

Propose a metabolic reaction which would illustrate a positive feedback mechanism. Be sure to address the relationship between molecules in the reaction (substrate, product, enzyme, etc) and how the reaction would be both perpetuated, and eventually terminated.

Since enzymes are essential in cellular function – it’s important to regulate their activity. There are several ways a cell can accomplish such regulation. How do cells regulate enzyme activity? (required minimum length 150 words)

Research has uncovered how bacteria which are antibiotic resistant protect bacteria which are not. For example, in an infected wound, an antibiotic resistant Gp A Strep will secrete the bacterial enzyme beta-lactamase. This enzyme will cut apart the beta-lactam ring on penicillins and cephalosporins. It destroys those antibiotics. Any other bacterial species in the wound, even those sensitive to penicillins and cephalosporins, are protected as well.

How could you prove that the growth you saw in the mixed section of the third plate was due to a single organism with antibiotic resistance to streptomycin and ampicillin rather than Strain A secreting a protein which protected Stain S from the ampicillin, and Strain S secreting a protein which protected Strain A from streptomycin?

533. You have added a drug that reduces the activity of the enzyme topoisomerase (gyrase). What will happen to the rate of activity of the helicase at the replication fork? Explain your reasoning.

534. You have added a drug that reduces the activity of the enzyme topoisomerase (gyrase). What will happen to the rate of activity of the DNA Polymerase activity on the leading strand? Explain your reasoning.

535. You have added a drug that reduces DNA Ligase activity. What will happen to the rate at which Okazaki fragments are joined on the lagging strand? Explain your reasoning.

536. You have added a drug that reduces DNA Ligase activity. What will happen to the rate at which Okazaki fragments are synthesized on the lagging strand? Explain your reasoning.

In one of the southern regions of the planet, several people were diagnosed with cholera. This is a particularly dangerous infectious disease that can spread rapidly if urgent measures are not taken. A patient with acute diarrhea, vomiting, muscle weakness, and spasms in the calf muscles was admitted to the admission department of the hospital. The skin of the hands is wrinkled, blood pressure is low. Examination of the patient confirmed the diagnosis of cholera. The causative agent of cholera, cholera vibrio, produces a toxin, one of the promoters of which is an enzyme - ADP-ribosyltransferase. Explain the mechanism of action of model toxin.
For an answer
1. Write the reactions catalyzed by this cholera toxin enzyme;
2. Explain the consequences of this reaction for the adenylate cyclase system in the cells of the intestinal mucosa;
3. Describe how cholera symptoms develop as a result of the toxin.

In some plants a red pigment is synthesized from a colorless precursor by a single enzyme coded for by gene A. The red pigment can be changed into a purple pigment by another enzyme coded for by gene B. A cross between pure-breeding purple plants and white plants with the resulting F₂:

94 purple

31 red

43 white

A. Give a concise genetic hypothesis for inheritance of flower color from these results (include number of genes, number of alleles, and the relations between genes and alleles).

B. Using symbols A and B to correspond to genes A and B as described above symbolize the genotypes and their ratios for each F₂ phenotypic class.

C. If the F₁ is used in a testcross, what phenotypic ratio would you expect in the progeny?