Question 1

Which of the following best describes the difference between constitutive and regulated gene expression in bacteria?

Accepted Answer

Constitutive genes are always expressed at a constant level, whereas regulated genes are expressed only under certain conditions.

Question 2

A mutation in the operator region of the lac operon prevents the repressor from binding. What is the most likely outcome for lac operon expression in the absence of lactose?

Accepted Answer

The operon will be constitutively expressed, even without lactose.

Question 3

Which of the following best illustrates negative control of gene expression in bacteria?

Accepted Answer

A repressor protein binds to the operator, blocking RNA polymerase and preventing transcription.

Question 4

In the trp operon, what is the role of tryptophan in regulating gene expression?

Accepted Answer

Tryptophan acts as a co-repressor, enabling the repressor to bind the operator and inhibit transcription.

Question 5

Which of the following is a key difference between cis-acting and trans-acting elements in eukaryotic gene regulation?

Accepted Answer

Cis-acting elements are DNA sequences that regulate genes on the same molecule, while trans-acting elements are usually diffusible proteins that can act on multiple DNA molecules.

Question 6

A researcher finds that a gene is silenced in one parent but expressed in the other, regardless of the offspring's genotype. Which phenomenon best explains this observation?

Accepted Answer

Genomic imprinting

Question 7

Which of the following best describes the mechanism of RNA interference (RNAi) in gene regulation?

Accepted Answer

RNAi uses small RNA molecules to target and degrade specific mRNA transcripts, reducing gene expression.

Question 8

A scientist uses a balancer chromosome in a Drosophila experiment. What is the primary purpose of a balancer chromosome?

Accepted Answer

To prevent crossing over and maintain deleterious mutations in a stable heterozygous state.

Question 9

In a complementation test, two mutants with similar phenotypes are crossed. The offspring display the wild-type phenotype. What does this indicate about the mutations?

Accepted Answer

The mutations are in different genes.

Question 10

Which of the following best describes the difference between forward and reverse genetics?

Accepted Answer

Forward genetics starts with a phenotype and identifies the gene, while reverse genetics starts with a gene and investigates the phenotype.

Question 11

A researcher is using CRISPR-Cas9 to introduce a specific point mutation into a gene. Which of the following best describes this approach?

Accepted Answer

Genome editing

Question 12

Which of the following sequencing strategies involves randomly breaking the genome into small fragments, sequencing them, and then assembling the sequences computationally?

Accepted Answer

Shotgun sequencing

Question 13

A patient is found to have a mutation in the TP53 gene. Which of the following best describes the likely consequence of this mutation?

Accepted Answer

Loss of tumor suppressor function, leading to increased cancer risk

Question 14

Which of the following is a hallmark of cancer progression from benign to malignant growth?

Accepted Answer

Cells acquire the ability to invade other tissues and metastasize.

Question 15

A researcher is analyzing gene expression using microarray technology. Which of the following best describes the principle behind this method?

Accepted Answer

Microarrays measure the hybridization of labeled cDNA to thousands of DNA probes fixed on a solid surface.

Question 16

Which of the following best describes the process of gene amplification in cancer?

Accepted Answer

Multiple copies of a gene are generated, leading to overexpression and potential oncogenic effects.

Question 17

A scientist is using Illumina sequencing to analyze a human genome. Which of the following is a key feature of Illumina sequencing technology?

Accepted Answer

It uses sequencing-by-synthesis with reversible terminator nucleotides.

Question 18

Which of the following equations correctly represents the probability of two independent events A and B both occurring?

Accepted Answer

$$P(A \ 	ext{and} \ B) = P(A) 	imes P(B)$$

Question 19

A patient inherits a mutated BRCA1 allele from one parent and a normal allele from the other. Which of the following best describes the patient's cancer risk?

Accepted Answer

The patient has an increased risk of developing cancer due to loss of heterozygosity.

Question 20

Which of the following best describes the phenomenon of chromothripsis in cancer genomes?

Accepted Answer

A single catastrophic event shatters a chromosome, followed by random reassembly of the fragments.

Genetics Exam 3 Study Guide: Gene Regulation, Genetic Technologies, Genomics, and Cancer Genetics

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