Question 1

Which experiment provided the most direct evidence that DNA is the hereditary material in cells?

Accepted Answer

Avery, MacLeod, and McCarty's experiment using DNase, RNase, and protease

Question 2

According to Chargaff’s rule, if a DNA sample contains 30% adenine, what percentage of guanine does it contain?

Accepted Answer

20%

Question 3

Which of the following best describes the structure of DNA as modeled by Watson and Crick?

Accepted Answer

A double helix with antiparallel sugar-phosphate backbones and complementary base pairs

Question 4

If the sequence of a DNA template strand is 5'-ATCGGTA-3', what is the sequence and polarity of the newly synthesized complementary strand?

Accepted Answer

3'-TAGCCAT-5'

Question 5

Which bond type is responsible for holding together the two strands of the DNA double helix?

Accepted Answer

Hydrogen bonds

Question 6

What is the main problem encountered during the replication of the ends of linear chromosomes (telomeres)?

Accepted Answer

The lagging strand cannot be fully replicated, leading to progressive shortening

Question 7

How does telomerase solve the problem of replicating telomeres?

Accepted Answer

By adding repetitive DNA sequences to the 3' end using its own RNA template

Question 8

Which experimental approach did Meselson and Stahl use to demonstrate that DNA replication is semiconservative?

Accepted Answer

Density gradient centrifugation with $$^{15}N$$ and $$^{14}N$$

Question 9

In a bacterial chromosome, DNA replication begins at a single origin and proceeds in both directions. What is the term for the region where DNA is actively being synthesized?

Accepted Answer

Replication fork

Question 10

Which enzyme is responsible for joining Okazaki fragments during DNA replication?

Accepted Answer

DNA ligase

Question 11

A eukaryotic chromosome contains multiple origins of replication. What is the primary advantage of this arrangement?

Accepted Answer

It allows the entire genome to be replicated more quickly

Question 12

Which histone proteins are found in the core of a nucleosome?

Accepted Answer

H2A, H2B, H3, H4

Question 13

Which feature of DNA allows proteins to recognize specific sequences for binding and regulation?

Accepted Answer

The major and minor grooves exposing base pairs

Question 14

During dideoxynucleotide sequencing (Sanger sequencing), what is the role of dideoxynucleotides?

Accepted Answer

They terminate DNA strand elongation at specific bases

Question 15

Which of the following equations correctly represents the central dogma of molecular biology?

Accepted Answer

$$DNA \rightarrow RNA \rightarrow Protein$$

Question 16

If a DNA molecule is 1000 base pairs long and each nucleosome wraps 147 base pairs of DNA, approximately how many nucleosomes are required to package this DNA?

Accepted Answer

$$\frac{1000}{147} \approx 6.8$$, so 7 nucleosomes

Question 17

Which of the following statements about DNA replication in eukaryotes is correct?

Accepted Answer

Replication begins at multiple origins per chromosome

Question 18

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Question 19

A patient’s cells show rapid telomere shortening and early cell senescence. Which enzyme is most likely deficient?

Accepted Answer

Telomerase

Question 20

Which of the following best explains why DNA replication is described as 'semiconservative'?

Accepted Answer

Each new DNA molecule contains one parental strand and one newly synthesized strand

Genetic Analysis: DNA Structure, Replication, and Chromatin Organization – Week 9 Study Guide

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