Question 1

Which experiment provided the first strong evidence that DNA is the genetic material responsible for inheritance?

Accepted Answer

Griffith's transformation experiment with Streptococcus pneumoniae

Question 2

In Griffith's experiment, what was the result when heat-killed pathogenic S cells were mixed with living nonpathogenic R cells and injected into mice?

Accepted Answer

The mice died, and living S cells were recovered from them

Question 3

Chargaff's rules state that in any species of DNA, which of the following relationships is true?

Accepted Answer

$$[A] = [T]$$ and $$[G] = [C]$$

Question 4

Which technique did Rosalind Franklin use to help reveal the double helical structure of DNA?

Accepted Answer

X-ray crystallography

Question 5

What is the structural reason that a purine always pairs with a pyrimidine in the DNA double helix?

Accepted Answer

It maintains a uniform diameter of the helix

Question 6

During DNA replication, which enzyme is responsible for unwinding the double helix at the replication fork?

Accepted Answer

Helicase

Question 7

Why is an RNA primer necessary for DNA polymerase to begin synthesis of a new DNA strand?

Accepted Answer

DNA polymerase can only add nucleotides to an existing 3' end

Question 8

Which of the following best describes the difference between the leading and lagging strands during DNA replication?

Accepted Answer

The leading strand is synthesized continuously, while the lagging strand is synthesized in fragments

Question 9

What is the role of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments together on the lagging strand

Question 10

Which DNA repair mechanism involves a nuclease cutting out and replacing damaged stretches of DNA?

Accepted Answer

Nucleotide excision repair

Question 11

Why do eukaryotic chromosomes have telomeres at their ends?

Accepted Answer

To postpone the erosion of genes near the ends of DNA molecules

Question 12

What is the evolutionary significance of mutations in DNA?

Accepted Answer

They are the source of genetic variation upon which natural selection acts

Question 13

Which enzyme catalyzes the lengthening of telomeres in germ cells?

Accepted Answer

Telomerase

Question 14

What is the main difference between bacterial and eukaryotic chromosomes?

Accepted Answer

Bacterial chromosomes are circular and have less protein, while eukaryotic chromosomes are linear and have more protein

Question 15

Which of the following best describes a nucleosome?

Accepted Answer

DNA wound twice around a core of eight histone proteins

Question 16

If a DNA molecule has 20% adenine, what percentage of guanine would you expect according to Chargaff's rules?

Accepted Answer

30%

Question 17

Which of the following statements about chromatin is correct?

Accepted Answer

Euchromatin is loosely packed and accessible for gene expression, while heterochromatin is tightly packed and less accessible

Question 18

Which direction does DNA polymerase synthesize new DNA?

Accepted Answer

5' to 3' direction

Question 19

A mutation occurs during DNA replication that is not corrected by proofreading or repair. What is the most likely consequence?

Accepted Answer

The mutation may become permanent and be passed on to future generations

Question 20

Which of the following best explains why repeated rounds of DNA replication in linear chromosomes can lead to shorter DNA molecules?

Accepted Answer

DNA polymerase cannot complete the 5' ends of daughter DNA strands

Chapter 16: The Molecular Basis of Inheritance – DNA Structure, Replication, and Packaging

Guida di studio - Domande di pratica

Study guide - Flashcard