Q: Which equation represents the hydrolysis of lactose by β-galactosidase?

$$\text{Lactose} + H_2O \xrightarrow{\beta\text{-galactosidase}} \text{Galactose} + \text{Glucose}$$

Question 1

Which of the following best describes the function of restriction enzymes in recombinant DNA technology?

Accepted Answer

They cleave DNA at specific nucleotide sequences, producing fragments with sticky or blunt ends.

Question 2

A researcher wants to clone a gene into a plasmid vector. Both the gene and the plasmid are cut with the same restriction enzyme. What is the next step to ensure the gene is inserted into the plasmid?

Accepted Answer

Mix the fragments with DNA ligase to seal the phosphodiester backbone.

Question 3

Which equation best represents the probability of finding a specific 6-base pair restriction site in a random DNA sequence?

Accepted Answer

$$P = \frac{1}{4^6$}$$

Question 4

Which property is NOT required for a DNA vector used in cloning?

Accepted Answer

Ability to synthesize proteins without inserted DNA.

Question 5

In blue-white screening, what is the expected outcome for a bacterial colony containing a recombinant plasmid with an interrupted lacZ gene?

Accepted Answer

The colony will appear white because β-galactosidase is not produced.

Question 6

Which of the following vectors is most suitable for cloning DNA fragments larger than 100 kb?

Accepted Answer

Bacterial artificial chromosome (BAC)

Question 7

A DNA sequence is palindromic if:

Accepted Answer

It reads the same from 5' to 3' on one strand and 3' to 5' on the complementary strand.

Question 8

Which equation represents the hydrolysis of lactose by β-galactosidase?

Accepted Answer

$$	ext{Lactose} + H_2O \xrightarrow{\beta	ext{-galactosidase}} 	ext{Galactose} + 	ext{Glucose}$$

Question 9

Which method is used to make bacterial cells competent for transformation?

Accepted Answer

Treating cells with calcium ions and heat shock.

Question 10

Which of the following is a real-world example of natural cloning?

Accepted Answer

Monozygotic twins in humans.

Question 11

Which equation best describes the relationship between the number of restriction sites ($$N) $$and the length of the recognition sequence ($$L) in a $$genome of size $$G$$?

Accepted Answer

$$N = \frac{G}{4^L}$$

Question 12

Which of the following statements about cDNA libraries is correct?

Accepted Answer

They are constructed from mRNA using reverse transcriptase.

Question 13

Which vector is specifically used to transform plant cells and integrate foreign DNA into the plant genome?

Accepted Answer

Ti plasmid from Rhizobium radiobacter

Question 14

A genomic library is constructed by:

Accepted Answer

Cutting genomic DNA with restriction enzymes and ligating fragments into vectors.

Question 15

Which of the following is a key advantage of using Saccharomyces cerevisiae as a host for DNA cloning?

Accepted Answer

It can posttranslationally modify eukaryotic proteins.

Question 16

Which step is necessary to recover a specific gene from a DNA library?

Accepted Answer

Screening the library with a probe complementary to the target gene.

Question 17

Which cloning method involves transferring a donor cell nucleus into an enucleated egg?

Accepted Answer

Somatic cell nuclear transfer

Question 18

Which of the following is NOT a limitation of bacterial plasmids as cloning vectors?

Accepted Answer

They can be used to clone large DNA fragments over 100kb.

Question 19

Which equation represents the annealing of sticky ends produced by EcoRI?

Accepted Answer

$$	ext{AATT} + 	ext{AATT} ightarrow 	ext{AATT-AATT}$$

Recombinant DNA Technology: Tools, Methods, and Applications

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