Question 1

Which model of DNA replication is supported by the Meselson-Stahl experiment, and what is the key feature of this model?

Accepted Answer

Semiconservative replication; each daughter DNA molecule consists of one parental and one newly synthesized strand.

Question 2

During bacterial DNA replication, which protein is responsible for relieving the torsional strain ahead of the replication fork?

Accepted Answer

DNA topoisomerase

Question 3

What is the primary function of primase (DnaG) during DNA replication?

Accepted Answer

Synthesizes short RNA primers to provide a 3' end for DNA polymerase

Question 4

Which of the following best describes the directionality of DNA synthesis by DNA polymerases?

Accepted Answer

5' to 3' direction only

Question 5

In E. coli, what is the role of the DnaA protein at the origin of replication (oriC)?

Accepted Answer

It binds to DnaA boxes and helps unwind the AT-rich region to initiate replication.

Question 6

Why is it logical for the origin of replication in E. coli to contain an AT-rich region?

Accepted Answer

AT base pairs have fewer hydrogen bonds than GC pairs, making them easier to separate.

Question 7

Which enzyme is responsible for removing RNA primers and replacing them with DNA nucleotides in prokaryotic DNA replication?

Accepted Answer

DNA polymerase I

Question 8

What is the function of single-stranded binding proteins (SSBs) during DNA replication?

Accepted Answer

They prevent separated DNA strands from re-annealing.

Question 9

Which of the following equations correctly represents the exponential amplification of DNA during PCR, where $$n is $$the number of cycles?

Accepted Answer

$$2^n$$

Question 10

Why is Taq polymerase used in PCR instead of other DNA polymerases?

Accepted Answer

It is relatively heat insensitive and can withstand the high temperatures used in PCR.

Question 11

What is the main reason eukaryotic chromosomes require telomeres?

Accepted Answer

To protect chromosome ends from degradation due to incomplete lagging strand replication.

Question 12

Which enzyme is responsible for joining Okazaki fragments on the lagging strand during DNA replication?

Accepted Answer

DNA ligase

Question 13

In Sanger sequencing, what is the effect of incorporating a dideoxynucleotide (ddNTP) into a growing DNA strand?

Accepted Answer

It terminates DNA synthesis at that position.

Question 14

Which DNA polymerase is primarily responsible for leading strand synthesis in eukaryotes?

Accepted Answer

DNA polymerase epsilon

Question 15

A mutation in the gene encoding flap endonuclease (FEN1) in eukaryotes would most directly affect which process?

Accepted Answer

Removal of RNA primers from lagging strand fragments

Question 16

Which of the following best explains why DNA polymerases have high fidelity during replication?

Accepted Answer

They possess 3' to 5' exonuclease activity for proofreading.

Question 17

In a paternity test using variable number tandem repeats (VNTRs), what is the genetic principle that allows identification of parentage?

Accepted Answer

VNTRs are inherited in a Mendelian fashion, so a child’s VNTR alleles must match those of at least one parent.

Question 18

Which of the following is NOT a component required for a standard PCR reaction?

Accepted Answer

Single-stranded DNA binding proteins

Question 19

What is the main difference between bacterial and eukaryotic DNA replication origins?

Accepted Answer

Bacteria have a single origin per chromosome, eukaryotes have multiple.

Question 20

Which of the following best describes the role of Tus protein in E. coli DNA replication?

Accepted Answer

It blocks the progression of the replication fork at the termination site.

Chapter 7

Guida di studio - Domande di pratica