Question 1

During DNA replication, which enzyme is responsible for removing RNA primers from the newly synthesized DNA strands?

Accepted Answer

Exonuclease

Question 2

A mutation in the gene encoding single-stranded binding proteins (SSBPs) would most likely result in which of the following problems during DNA replication?

Accepted Answer

Premature re-annealing of separated DNA strands

Question 3

Which of the following best describes the semiconservative nature of DNA replication?

Accepted Answer

Each new DNA molecule contains one parental and one new strand

Question 4

A cell is observed to have condensed chromatin, duplicated centrosomes at opposite poles, and a disintegrating nuclear envelope. Which stage of mitosis is this cell most likely in?

Accepted Answer

Prophase

Question 5

Which of the following molecular events is directly responsible for the transition from G2 phase to M phase in the cell cycle?

Accepted Answer

Formation of the Mitosis-Promoting Factor (MPF) complex

Question 6

A researcher treats cells with a drug that inhibits Histone Acetyltransferase (HAT) activity. What is the most likely effect on gene expression?

Accepted Answer

Decreased transcription due to heterochromatin formation

Question 7

Which checkpoint in the cell cycle ensures that all chromosomes are properly attached to the spindle apparatus before anaphase begins?

Accepted Answer

M (Spindle Assembly) Checkpoint

Question 8

A cell with a mutated, nonfunctional p53 protein is exposed to DNA-damaging radiation. What is the most likely outcome?

Accepted Answer

The cell will proceed through the cell cycle with damaged DNA

Question 9

During apoptosis, which event distinguishes it from necrosis at the cellular level?

Accepted Answer

Formation of membrane-bound apoptotic bodies

Question 10

Which of the following correctly matches the C. elegans apoptosis gene with its human homolog?

Accepted Answer

ced-4 = Apaf-1

Question 11

A patient is diagnosed with a tumor that overexpresses Bcl-2. Which of the following best explains how this contributes to cancer development?

Accepted Answer

Bcl-2 inhibits apoptosis, allowing damaged cells to survive

Question 12

Which of the following sequences correctly describes the order of events in the intrinsic (mitochondrial) pathway of apoptosis?

Accepted Answer

DNA damage → p53 activation → Bax/Bak pore formation → Cytochrome c release → Apoptosome assembly

Question 13

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

Accepted Answer

DNA Ligase

Question 14

A cell is observed to have chromosomes aligned single file at the cell's equator, with spindle fibers attached to kinetochores. Which mitotic stage is this?

Accepted Answer

Metaphase

Question 15

Which of the following best explains why telomerase activity is important during DNA replication?

Accepted Answer

It maintains telomeric repeat sequences to prevent loss of genetic material

Question 16

Which of the following is a direct substrate for executioner caspases during apoptosis?

Accepted Answer

Nuclear lamins

Question 17

A scientist observes a cell with a contractile ring of actin and myosin pinching the plasma membrane inward. What process is being observed?

Accepted Answer

Cytokinesis

Question 18

Which of the following equations best represents the semiconservative model of DNA replication?

Accepted Answer

$$	ext{Parent DNA} ightarrow 	ext{Daughter DNA}_1 (	ext{one parent strand} + 	ext{one new strand}) + 	ext{Daughter DNA}_2 (	ext{one parent strand} + 	ext{one new strand})$$

Question 19

Which of the following best describes the role of p21 in the cell cycle?

Accepted Answer

It inhibits cyclin-dependent kinases to arrest the cell cycle for DNA repair

Step-by-Step Guidance for Microbiology: DNA Replication, Cell Cycle, and Apoptosis

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