Question 1

Which of the following best describes the function of telomeres in eukaryotic chromosomes?

Accepted Answer

They protect chromosome ends from degradation and prevent the loss of genetic information during replication.

Question 2

Why does the end-replication problem occur in linear DNA molecules during replication?

Accepted Answer

DNA polymerase can only add nucleotides to the 3' end of a pre-existing polynucleotide.

Question 3

Which enzyme is responsible for extending telomeres in germ cells, and what is its mechanism?

Accepted Answer

Telomerase; it adds repetitive DNA sequences to the 3' end using an RNA template.

Question 4

What is the repeated DNA sequence found in human telomeres?

Accepted Answer

$$\mathrm{TTAGGG}$$

Question 5

Which of the following statements about telomerase activity is correct?

Accepted Answer

Telomerase is active in germ cells but not in most normal somatic cells.

Question 6

A mutation causes a cell to lose telomerase activity. What is the most likely long-term consequence for this cell line?

Accepted Answer

The telomeres will shorten with each cell division, eventually leading to cell senescence.

Question 7

During DNA replication, why is the lagging strand more affected by the end-replication problem than the leading strand?

Accepted Answer

The lagging strand requires multiple RNA primers, and the final primer cannot be replaced with DNA.

Question 8

Which of the following best explains why telomeres are composed of non-coding, repetitive DNA sequences?

Accepted Answer

To ensure that essential genes are not lost during DNA replication.

Question 9

Suppose a researcher observes that a certain cancer cell line has high telomerase activity. What is a likely consequence of this observation?

Accepted Answer

The cancer cells will maintain their telomere length and continue dividing indefinitely.

Question 10

Which of the following equations correctly represents the directionality of DNA synthesis by DNA polymerase?

Accepted Answer

$$5' \rightarrow 3'$$

Question 11

A scientist is studying a rare genetic disorder in which telomeres are abnormally short in somatic cells. Which of the following symptoms might be expected in affected individuals?

Accepted Answer

Increased risk of early cell senescence and tissue degeneration.

Question 12

Which process is directly responsible for the removal of RNA primers during DNA replication?

Accepted Answer

DNA polymerase I

Question 13

If a mutation caused telomerase to be active in all somatic cells, what would be a likely consequence?

Accepted Answer

Somatic cells would become immortal, increasing the risk of cancer.

Question 14

Which of the following best explains why telomerase is not active in most adult somatic cells?

Accepted Answer

To limit the number of cell divisions and reduce the risk of cancer.

Question 15

Which of the following is a direct consequence of the inability to replicate the very ends of linear chromosomes?

Accepted Answer

Progressive shortening of chromosomes with each cell division.

DNA Structure, Replication, and Telomere Maintenance

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