Question 1

Which of the following is NOT an expected property of genetic material according to the lecture?

Accepted Answer

It must be highly stable to account for reproducible generation of traits.

Question 2

Which chemical bond is responsible for joining adjacent nucleotides in a single DNA strand?

Accepted Answer

Phosphodiester bond

Question 3

In double-stranded DNA, the two strands are described as antiparallel. What does this mean?

Accepted Answer

One strand runs 5' to 3', and the other runs 3' to 5'.

Question 4

Which base pairing is correct in double-stranded DNA?

Accepted Answer

A pairs with T, G pairs with C

Question 5

What is the regular spacing of base pairs per helical turn in B-form DNA?

Accepted Answer

$10.5$ base pairs per turn

Question 6

Major and minor grooves in DNA arise due to:

Accepted Answer

The angles at which the bases protrude from the backbone

Question 7

Why do mismatched base pairs distort the helical structure of DNA?

Accepted Answer

They have different geometry compared to complementary base pairs

Question 8

Proteins that bind DNA sequence-specifically often interact with which part of the DNA double helix?

Accepted Answer

Major groove

Question 9

Which process describes the separation of double-stranded nucleic acids into single strands?

Accepted Answer

Denaturation

Question 10

What is the linking number ($L_k$) in the context of DNA topology?

Accepted Answer

The number of times each strand is wound around the axis of the helix

Question 11

Topoisomerases are essential during DNA replication because they:

Accepted Answer

Change the linking number of DNA molecules

Question 12

Most organisms store their DNA in which supercoiled form?

Accepted Answer

Negatively supercoiled

Question 13

Which of the following statements about eukaryotic chromosomes is TRUE?

Accepted Answer

They are linear and typically present in two copies per cell.

Question 14

A scientist isolates DNA from a cell and finds it is circular and contains extra-chromosomal plasmids. This DNA most likely comes from:

Accepted Answer

A prokaryote such as E. coli

Question 15

Which of the following best describes hybridization in nucleic acids?

Accepted Answer

The sequence-specific pairing of complementary nucleic acid strands

Question 16

If a DNA molecule has a linking number ($L_k$) of 20 and is negatively supercoiled, what does this indicate about its structure compared to relaxed B-form DNA?

Accepted Answer

It has fewer turns per 10.5 base pairs than relaxed DNA.

Question 17

Which feature of DNA allows repair enzymes to detect mismatches?

Accepted Answer

Distortion of the helical structure due to mismatched base pairs

Question 18

Which of the following is a pyrimidine nucleotide found in DNA?

Accepted Answer

Thymine

Question 19

A mutation causes a protein to bind only in the minor groove of DNA. Which of the following is most likely affected?

Accepted Answer

Sequence-specific DNA binding by transcription factors

Question 20

Which statement about the backbone of DNA is correct?

Accepted Answer

It is composed of alternating sugar and phosphate groups.

DNA and Chromosome Structure: Molecular Basis and Organization

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