Question 1

During DNA replication, which enzyme is responsible for relieving the torsional strain ahead of the replication fork by introducing transient breaks in the DNA?

Accepted Answer

Topoisomerase

Question 2

A mutation in the gene encoding DNA Polymerase I would most directly affect which process during DNA replication?

Accepted Answer

Removal of RNA primers and replacement with DNA

Question 3

Which of the following best describes the function of telomerase in eukaryotic cells?

Accepted Answer

It extends the 3' end of linear chromosomes using an RNA template.

Question 4

A researcher observes a mutation that changes a codon from UAU (tyrosine) to UAA (stop). What type of mutation is this, and what is its likely effect on the resulting protein?

Accepted Answer

Nonsense mutation; results in premature termination of translation

Question 5

Which of the following statements about the Wobble Hypothesis is correct?

Accepted Answer

It allows a single tRNA to recognize multiple codons due to non-standard base pairing at the third codon position.

Question 6

During translation, which ribosomal site is responsible for holding the tRNA carrying the growing polypeptide chain?

Accepted Answer

P site

Question 7

A cell is exposed to a chemical that inhibits the activity of the Anaphase Promoting Complex/Cyclosome (APC/C). What is the most immediate consequence for mitosis?

Accepted Answer

Securin will not be degraded, preventing activation of separase and thus blocking sister chromatid separation.

Question 8

Which of the following best distinguishes Non-Homologous End Joining (NHEJ) from Homologous Recombination (HR) in double-strand break repair?

Accepted Answer

NHEJ is more error-prone and does not require a homologous template, while HR is high-fidelity and uses a homologous sequence as a template.

Question 9

A cell is in the G2 phase of the cell cycle. Which of the following statements is true regarding its chromosomes?

Accepted Answer

Each chromosome consists of two sister chromatids joined at the centromere.

Question 10

During meiosis, which protein protects centromeric cohesin from cleavage during Anaphase I, ensuring that sister chromatids remain together?

Accepted Answer

Shugoshin (Sgo1)

Question 11

A plant cell and an animal cell are both undergoing cytokinesis. Which of the following correctly describes a key difference between these processes?

Accepted Answer

Animal cells form a cleavage furrow, while plant cells form a cell plate.

Question 12

A cell with a mutation in the gene encoding the Mad2 protein would most likely have defects in which process?

Accepted Answer

Spindle assembly checkpoint, leading to improper chromosome segregation

Question 13

Which of the following events increases genetic diversity during meiosis?

Accepted Answer

Crossing over between homologous chromosomes during Prophase I

Question 14

A test cross is performed between a pea plant with an unknown genotype for seed color (yellow is dominant, green is recessive) and a homozygous recessive plant. If all offspring are yellow, what is the genotype of the unknown parent?

Accepted Answer

Homozygous dominant (YY)

Question 15

Which of the following best describes the role of the 5' methylguanosine cap added during eukaryotic mRNA processing?

Accepted Answer

It protects mRNA from degradation and assists in ribosome binding during translation.

Question 16

A frameshift mutation occurs early in the coding region of a gene. What is the most likely consequence for the resulting protein?

Accepted Answer

The reading frame is altered, resulting in a completely different and likely nonfunctional protein.

Question 17

Which of the following equations correctly represents the number of possible gamete genotypes produced by an organism with $$n$$ heterozygous gene pairs, according to Mendel's law of independent assortment?

Accepted Answer

$$2^n$$

Question 18

During translation initiation in eukaryotes, which sequence is recognized to position the ribosome at the correct start codon?

Accepted Answer

Kozak sequence

Question 19

Which of the following best explains why Okazaki fragments are formed during DNA replication?

Accepted Answer

DNA polymerase can only synthesize DNA in the 5' to 3' direction, so the lagging strand is synthesized discontinuously.

Question 20

A patient is found to have a genetic disorder caused by a single nucleotide change that does not alter the amino acid sequence of the encoded protein. What type of mutation is this?

Accepted Answer

Silent mutation

DNA Replication, Gene Expression, and Cell Division: Study Guide for BIO 043

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