1. If the proofreading mechanism of the DNA Polymerase fails, what else can the cell do...

1. If the proofreading mechanism of the DNA Polymerase fails, what else can the cell do to fix mistakes?

2. A cell, not during the process of DNA replication, has 2 nucleotides (both T's) that formed a dimer in a single strand. The two dimerized nucleotides aren't base-pairing to the complementary strand.

a) What do you think caused this to occur?

b) what would normally happen in this situation?

C) What if the enzyme, Nuclease, was inactivated in that cell.. what would or wouldn't happen?

d) If there were no nuclease, what would happedn the next time the cell divides ?

Solutions

Expert Solution

1. If the proofreading mechanism of the DNA Polymerase fails, what else can the cell do to fix mistakes?

Answer: Proofreading is a activity the fucntion of most of the bacterial DNA polymerases. If the proofreading mechanism of the DNA Polymerase fails leads to a thousandfold increase in the rate of spontaneous mutations. But E. coli have an additional mismatch-repair mechanism to check the fidelity of DNA replication by identifying the mispaired nitrogenous bases in newly replicated DNA. Mismatch-repair mechanism determines which strand is to be repaired by distinguishing the newly replicated strand (the one in which an error occurred during replication) from the template strand.

2. a) What do you think caused this to occur?

Answer: This is occured due to exposure of DNA or cell to UV radiation that cuased the formation of thymine dimers.

2. b) what would normally happen in this situation?

Answer: Normally in presence of light the photo-repair mechanism will activate in presence of light and repair the damaged DNA other wise in absence of light the Excision repair mechanism works with the help of nuclease enzyme and remove the dimer and replace it with new nucleotides.

2. C) What if the enzyme, Nuclease, was inactivated in that cell.. what would or wouldn't happen?

Answer: If the Nuclease was inactivated the repair mechanism fails and the dimer structure wouldn't repaired in absence of light by Excision repair mechanism.

d) If there were no nuclease, what would happedn the next time the cell divides ?

Answer: When cell divides leads to misincorporation of wrong nucleotides at the site of thymine dimer and leads to mutation in dividing cells

gladiator answered 1 year ago

Next > < Previous

Related Solutions

Compare the proofreading mechanisms of DNA and RNA polymerase. Specifically, which active site is required for...

Compare the proofreading mechanisms of DNA and RNA polymerase. Specifically, which active site is required for proofreading by each enzyme and what are the products of this activity?

1. In what ways can a primer for DNA synthesis by a DNA polymerase be provided?...

1. In what ways can a primer for DNA synthesis by a DNA polymerase be provided? 2. In E.coli, how are the Okazaki fragments of the lagging strands joined to create a complete DNA duplex? 3. What are the three eukaryotic nuclear DNA replicases and their functions? How is DNA replication of a circular bacterial chromosome terminated?

1. If a cell cannot properly create DNA polymerase which step of replication would this cell...

1. If a cell cannot properly create DNA polymerase which step of replication would this cell be incapable of performing? Explain why 2. It is possible to compare transcription to a race car moving along a track. In transcription which units or structures would be analogous to the following: the car, a green light, the track, and a stop sign? 3. Describe the relationship between the sequence of the mRNA molecule and the amino acid sequence of the resulting protein.

Why are DNA proofreading enzymes necessary? A DNA molecule can be thought of as having 2...

Why are DNA proofreading enzymes necessary? A DNA molecule can be thought of as having 2 components, corresponding to the sides and rungs of a ladder. What are these 2 components? What class of molecule is telomerase? What does telomerase do? In which human cells is telomerase appropriately active? In what kinds of cells is telomerase inappropriately active?

DNA polymerase can sometimes make mistakes. When this is detected the cell cycle halts and works...

DNA polymerase can sometimes make mistakes. When this is detected the cell cycle halts and works on repairing the mistakes. List two genes that, when their function is lost, would not allow cells to halt their cell cycle. Please explain in a sentence or two why the loss of function mutations in each gene would have this effect.?

1. Why does E. coli need both DNA polymerase III and DNA polymerase I? a. The...

1. Why does E. coli need both DNA polymerase III and DNA polymerase I? a. The DNA replication is bidirectional; one polymerase is used for each direction. b. Each polymerase is specific for only one strand of DNA. DNA polymerase III acts only on the leading strand, and DNA polymerase I acts only on the lagging strand. c. Only DNA polymerase I has proofreading ability. d. DNA polymerase III lacks the 5' → 3' exonuclease activity needed to remove RNA...

1. What is DNA polymerase? Explain the roles of its various components in DNA replication. 2....

1. What is DNA polymerase? Explain the roles of its various components in DNA replication. 2. What is RNA polymerase? Explain its role in transcription. How is RNA polymerase similar to and different from DNA polymerase?

Genetics Questions 1) What does “proofreading” refer to with regard to DNA replication? Briefly explain its...

Genetics Questions 1) What does “proofreading” refer to with regard to DNA replication? Briefly explain its mechanism. 2) All known DNA polymerases catalyze synthesis only in the 5' ? 3' direction. Nevertheless, during semiconservative DNA replication in the cell, they are able to catalyze the synthesis of both daughter chains, which would appear to require synthesis in the 3' ? 5' direction. Explain the process that occurs in the cell that allows for synthesis of both daughter chains by DNA...

What DNA products would be generated if one of the proteins including DNA polymerase, DNA ligase,...

What DNA products would be generated if one of the proteins including DNA polymerase, DNA ligase, sliding clamp for DNA polymerase, nuclease that removes DNA primers, DNA helicase, and primase, were missing?

What are the functions of the following enzymes in E. coli? DNA polymerase I __________________________________________________ DNA...

What are the functions of the following enzymes in E. coli? DNA polymerase I __________________________________________________ DNA polymerase II __________________________________________________ DNA polymerase III _________________________________________________ DNA polymerase IV _________________________________________________ DNA polymerase V _________________________________________________ Please indicate (if possible) which is the evolutionary history of these polymerases? Which of them you could be eliminate and preserve the function of the organism? (you must eliminate 2) What will be the consequences? Which environment might be suitable for the survival of this “mutant” that you created?

Subjects