Question 1

Which of the following best describes a transposon?

Accepted Answer

A sequence of DNA that can move from one location in the genome to another, potentially altering gene function.

Question 2

Which enzyme is responsible for the movement of DNA transposons?

Accepted Answer

Transposase

Question 3

Retrotransposons differ from DNA transposons in that retrotransposons:

Accepted Answer

Are transcribed into RNA, which is then reverse-transcribed into DNA and inserted elsewhere.

Question 4

Which process increases genome size over time?

Accepted Answer

Replicative transposition

Question 5

In the context of transposons, what is insertional inactivation?

Accepted Answer

A mutation caused by the insertion of a transposon into a gene, resulting in a nonfunctional gene product.

Question 6

Barbara McClintock discovered transposable elements by studying which organism?

Accepted Answer

Zea mays (corn)

Question 7

Which of the following is a real-world example of a transposon causing a visible phenotype?

Accepted Answer

The appearance of purple spots on otherwise yellow corn kernels due to Ds transposon movement.

Question 8

Which of the following statements about homologous recombination is correct?

Accepted Answer

It occurs during prophase I of meiosis and involves the exchange of genetic material between homologous chromosomes.

Question 9

Which enzyme is required for retrotransposon movement?

Accepted Answer

Reverse transcriptase

Question 10

What is the role of flanking direct repeats in transposon insertion?

Accepted Answer

They are created during insertion and mark the boundaries of the inserted transposon.

Question 11

Which of the following is a consequence of transposon activity in the human genome?

Accepted Answer

Transposons can cause mutations that lead to hereditary diseases.

Question 12

Which type of transposable element is most abundant in the human genome?

Accepted Answer

Retrotransposons

Question 13

Which of the following is true regarding the central dogma and retrotransposons?

Accepted Answer

Retrotransposons are an exception to the central dogma because they use reverse transcriptase to convert RNA back into DNA.

Question 14

During homologous recombination, what is the function of the Holliday junction?

Accepted Answer

It is a DNA structure where strands from homologous chromosomes cross over, allowing genetic exchange.

Question 15

Which resolution of the Holliday junction results in recombinant chromosomes?

Accepted Answer

Opposite sense resolution

Question 16

A scientist wants to insert a new gene into a yeast chromosome using homologous recombination. What strategy should they use?

Accepted Answer

Provide the new gene with flanking sequences homologous to the target site to promote recombination.

Question 17

Which of the following best explains why most transposons in the human genome are inactive?

Accepted Answer

They have been silenced by DNA methylation and lost the ability to move over evolutionary time.

Question 18

If a transposon inserts into the coding region of a gene, what is the most likely outcome?

Accepted Answer

The gene will produce a nonfunctional protein due to insertional inactivation.

Question 19

Which equation best represents the process of retrotransposon movement?

Accepted Answer

$$DNA \rightarrow RNA \rightarrow DNA$$

Question 20

A population of peas has a wrinkled seed phenotype due to a transposon insertion in the SBE1 gene. Which genetic principle does this illustrate?

Accepted Answer

Insertional inactivation creating a recessive allele.

Transposons and Homologous Recombination: Mechanisms and Genomic Consequences

Study Guide - Practice Questions