Question 1

Homologous recombination is ــــــــــــــــــــ.
A)the exchange of DNA between similar sequences
B)the exchange of DNA between dissimilar sequences
C)the formation of a heteroduplex
D)the removal of a holiday junction

Accepted Answer

Homologous recombination involves the exchange of DNA between similar sequences, such as between two homologous chromosomes, and can result in genetic diversity and repair of DNA damage. Choices B, C, and D are not accurate descriptions of homologous recombination.

Question 2

Which enzyme is required for resolution of the Holliday junction?
A)resolvase
B)integrase
C)recombinase
D)excisionase

Accepted Answer

Resolvase is the enzyme that is required for the resolution of the Holliday junction. It cleaves the DNA at the point where the junction has formed, allowing the strands to separate and the process of recombination to be completed. Integrase, recombinase, and excisionase are enzymes that are involved in other types of genetic recombination but are not directly involved in resolving the Holliday junction.

Question 3

Which of the following proteins is required for lambda integration in the genome of Escherichia coli?
A)transposase
B)resolvase
C)Int protein
D)Xis protein

Accepted Answer

Lambda integration into the genome of E. coli requires the Int protein. The Int protein catalyzes the recombination of the phage and bacterial DNA to form a stable integrated prophage. The transposase and resolvase are enzymes involved in transposition and resolution of transposable elements, while Xis protein is involved in the excision of lambda from the bacterial genome.

Question 4

Site specific recombination only occurs for homologous sequences.

Accepted Answer

Site-specific recombination can occur between homologous or non-homologous sequences, as long as they have a specific recognition sequence for the recombination enzyme.

Question 5

The Holliday junction only forms during excision.

Accepted Answer

The Holliday junction can form during both excision and recombination processes.

Question 6

Mutations in RAD genes causeــــــــــــــــــــــ .
A)recombination to occur randomly
B)radiation sensitivity
C)excessive recombination events during meiosis
D)a decline in gamete production

Accepted Answer

RAD genes are involved in DNA repair processes, particularly in response to radiation damage. Mutations in these genes can lead to increased sensitivity to radiation because the cell's ability to repair DNA damage caused by radiation is compromised.

Question 7

A heteroduplex is a double helix with two strands from different DNA or RNA molecules.

Accepted Answer

A heteroduplex is formed when two strands from different DNA or RNA molecules come together and form a double helix. This can occur during genetic recombination or when two different strands are artificially hybridized in the lab.

Question 8

Chi sites are ــــــــــــــــــــ.
A)generated from Holliday junctions
B)inverted repeats
C)binding sites for RecA protein
D)specific sequences in prokaryotic genomes where crossovers occur

Accepted Answer

Chi sites are specific sequences in prokaryotic genomes where crossovers occur. They are used by Recombinases to direct the crossover events, facilitating the repair of DNA damage.

Question 9

Xis protein ـــــــــــــــــــــ.
A)is involved in X-inactivation in female animals
B)helps recombine homologous sequences
C)is used to excise previously recombined DNA segments
D)all of the above

Accepted Answer

The answer of Xis protein ـــــــــــــــــــــ.
A)is involved in X-inactivation in...

Question 10

RAD genes are essential for recombination events during both mitosis and meiosis.

Accepted Answer

RAD genes encode for proteins involved in DNA repair and recombination, which occurs during both mitosis and meiosis. Therefore, RAD genes are essential for recombination events during both processes.

Quiz 24: Recombination

Homologous recombination is ــــــــــــــــــــ.

Which enzyme is required for resolution of the Holliday junction?

Which of the following proteins is required for lambda integration in the genome of Escherichia coli?

Site specific recombination only occurs for homologous sequences.

The Holliday junction only forms during excision.

Mutations in RAD genes causeــــــــــــــــــــــ .

A heteroduplex is a double helix with two strands from different DNA or RNA molecules.

Chi sites are ــــــــــــــــــــ.

Xis protein ـــــــــــــــــــــ.

RAD genes are essential for recombination events during both mitosis and meiosis.