Question 1

Explain how a bacterium living in a biofilm behaves very similar to a primitive multicellular organism.

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Question 2

Using the central dogma of molecular biology, explain how an organism's genotype influences its phenotype.

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Question 3

Many mutagens cause a rate of mutation that promotes the development of cancers; such mutagens are called carcinogens.

Accepted Answer

Mutagens are agents that cause mutations in the DNA, and when these mutations occur in genes that control cell growth and division, they can lead to cancer. Carcinogens are a subset of mutagens that specifically cause cancer by increasing the rate of mutations.

Question 4

Both prokaryotes and eukaryotes have several types of pre and post- transcriptional regulation. What advantage does pre- transcriptional regulation have over post- transcriptional regulation and vice versa? Name three examples of each type of regulation.

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Question 5

Gyrase breaks the hydrogen bonds between DNA strands and unwinds the DNA strands while topoisomerases relieve the coiling tension that develops as the helix unwinds.

Accepted Answer

Gyrase, a type of topoisomerase, specifically introduces negative supercoils into DNA, relieving the tension from supercoiling, while topoisomerases more broadly can either introduce or remove supercoils and are involved in untangling DNA. The breaking of hydrogen bonds between DNA strands is primarily the job of helicases during DNA replication.

Question 6

Introns shouldn't be perceived as junk or a nuisance, rather, they provide an opportunity for genetic diversity.

Accepted Answer

Introns can enhance genetic diversity through alternative splicing, allowing a single gene to produce multiple proteins. This process contributes to the complexity and adaptability of organisms.

Question 7

Describe the four scenarios of Griffith's experiment in the 1920s and summarize the main conclusion.

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Question 8

A sequence of cDNA would contain introns but no exons.

Accepted Answer

cDNA is synthesized from mature mRNA, which has already had introns removed during the process of splicing, thus it contains only exons.

Question 9

A repressible operon produces a repressor that is inactive from the start.

Accepted Answer

In a repressible operon, the repressor is initially inactive and becomes active only when it binds to a corepressor, typically the end product of the operon's metabolic pathway.

Question 10

DNA replication is a semiconservative process.

Accepted Answer

During DNA replication, each of the two strands of the original DNA molecule serves as a template for the production of a complementary strand, resulting in two new DNA molecules, each containing one original and one new strand.

Question 11

Which of the following is true about retrotransposons?

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Question 12

A reversion mutation is when a base- substitution mutation is changed back to the original DNA sequence.

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Question 13

An organism's genotype influences its phenotype.

Accepted Answer

The genotype of an organism, which is its genetic makeup, directly influences its phenotype, which are the observable characteristics or traits.

Question 14

What are the differences between DNA replication on the leading and lagging strands and why do they exist?

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The answer of What are the differences between DNA replication...

Question 15

DNA transposons rely on the enzyme reverse transcriptase to insert a copy of cDNA into a new location in the genome.

Accepted Answer

DNA transposons move directly from one location in the genome to another without using reverse transcriptase, which is instead used by retrotransposons to transpose through an RNA intermediate.

Quiz 5: Genetics