Q: Which of the following best describes the central dogma of molecular biology?

$$\text{DNA} \rightarrow \text{mRNA} \rightarrow \text{Protein}$$

Question 1

Which of the following best describes the difference between a gene and an allele?

Accepted Answer

A gene is a segment of DNA that codes for a protein, while an allele is a specific sequence variant of that gene.

Question 2

During which stage of mitosis do chromosomes align at the metaphase plate, and what is the significance of this alignment?

Accepted Answer

Metaphase; it ensures that each daughter cell receives an identical set of chromosomes.

Question 3

A diploid cell with $$2n = 8$$ chromosomes undergoes mitosis. How many chromosomes and DNA molecules will each daughter cell have immediately after cytokinesis?

Accepted Answer

$$8$$ chromosomes and $$8$$ DNA molecules

Question 4

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

Accepted Answer

Metaphase checkpoint

Question 5

In a species with $$n = 3$$ chromosome pairs, how many genetically distinct gametes can be produced by independent assortment alone (no crossing over)?

Accepted Answer

$$2^3 = 8$

Question 6

Which of the following events occurs during Prophase I of meiosis but NOT during Prophase of mitosis?

Accepted Answer

Synapsis and crossing over between homologous chromosomes

Question 7

A cell in G1 phase contains 10 picograms of DNA. How much DNA would be present in the same cell during metaphase of mitosis?

Accepted Answer

$$20$$ picograms

Question 8

Which protein complex holds sister chromatids together until anaphase, and which enzyme cleaves this complex to allow chromatid separation?

Accepted Answer

Cohesin; Separase

Question 9

A woman’s oocyte undergoes meiosis. If nondisjunction occurs during Anaphase I, what is the most likely chromosomal outcome in the resulting gametes?

Accepted Answer

Some gametes will have an extra chromosome (n+1), and some will be missing a chromosome (n-1).

Question 10

Which of the following best explains why polar bodies are useful in genetic diagnostics during in vitro fertilization (IVF)?

Accepted Answer

They contain the same genetic material as the oocyte and can be analyzed to infer the oocyte’s genotype.

Question 11

If a typical somatic cell has 32 chromosomes, how many chromosomes are expected in each gamete of that organism after meiosis?

Accepted Answer

$$16$$

Question 12

Which of the following is a direct consequence of crossing over during meiosis?

Accepted Answer

Increased genetic variation among gametes

Question 13

A mutation in the bub1 gene causes cells to fail to arrest at the metaphase checkpoint in the presence of spindle poisons. What is a likely consequence?

Accepted Answer

Chromosome missegregation and aneuploidy

Question 14

During which stage of meiosis does the reduction in chromosome number from diploid to haploid occur?

Accepted Answer

Anaphase I

Question 15

Which of the following statements about model organisms is correct?

Accepted Answer

They have stable genetic backgrounds, making them ideal for studying biological questions.

Question 16

If you follow 25 primary spermatocytes through spermatogenesis, how many spermatids will be produced?

Accepted Answer

$$100$$

Question 17

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

$$	ext{DNA} ightarrow 	ext{mRNA} ightarrow 	ext{Protein}$$

Question 18

Which of the following is a key difference between mitosis and meiosis?

Accepted Answer

Mitosis produces genetically identical cells, while meiosis produces genetically diverse gametes.

Question 19

A cell with a mutation in a cyclin-dependent kinase (CDK) gene fails to phosphorylate target proteins during the cell cycle. What is a likely outcome?

Accepted Answer

The cell cycle will be arrested at a checkpoint.

Cell Division: Mitosis and Meiosis – Genetics Study Guide

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