Question 1

Which of the following best describes a genomic library?

Accepted Answer

A collection of clones, each carrying copies of a particular DNA segment from a foreign genome, integrated into a vector, covering the entire genome.

Question 2

What is the main advantage of using a bacterial artificial chromosome (BAC) in constructing a DNA library?

Accepted Answer

BACs can carry large DNA inserts, allowing for fewer clones to cover the entire genome.

Question 3

A cDNA library differs from a genomic library in that:

Accepted Answer

A cDNA library contains only the genes expressed as mRNA in the original cells.

Question 4

Which enzyme is essential for creating a cDNA library from mRNA?

Accepted Answer

Reverse transcriptase

Question 5

In nucleic acid hybridization, what is the role of the probe?

Accepted Answer

To bind specifically to a complementary sequence in the gene of interest, allowing identification of clones carrying that gene.

Question 6

Why is it necessary to use a cDNA form of a eukaryotic gene when expressing it in bacteria?

Accepted Answer

Bacteria lack RNA-splicing machinery and cannot remove introns from eukaryotic genes.

Question 7

Which method is used to introduce recombinant DNA into eukaryotic cells by creating temporary holes in the plasma membrane?

Accepted Answer

Electroporation

Question 8

The polymerase chain reaction (PCR) amplifies DNA by cycling through which three steps?

Accepted Answer

Heating (denaturation), cooling (annealing), and replication (extension)

Question 9

Which equation best represents the exponential amplification of DNA in PCR after $$n$$ cycles, starting with one molecule?

Accepted Answer

$$2^n$$

Question 10

Gel electrophoresis separates DNA fragments based on:

Accepted Answer

Length (size) of the fragments

Question 11

Restriction fragment length polymorphism (RFLP) analysis is useful for:

Accepted Answer

Detecting genetic variation due to changes in restriction sites

Question 12

Southern blotting combines which two techniques to detect specific DNA fragments?

Accepted Answer

Gel electrophoresis and nucleic acid hybridization

Question 13

In the dideoxy chain termination method of DNA sequencing, what is the function of dideoxyribonucleotides (ddNTPs)?

Accepted Answer

They terminate DNA synthesis at specific bases, allowing identification of the nucleotide at the end of each fragment.

Question 14

Northern blotting is used to analyze:

Accepted Answer

mRNA expression at different developmental stages

Question 15

Reverse transcriptase-polymerase chain reaction (RT-PCR) is particularly useful for:

Accepted Answer

Comparing gene expression by amplifying cDNA from mRNA

Question 16

Which real-world scenario best illustrates the use of restriction fragment analysis?

Accepted Answer

Diagnosing sickle-cell disease by detecting a single nucleotide mutation in the β-globin gene

Question 17

Why might yeast cells be preferred over bacteria for expressing certain eukaryotic genes?

Accepted Answer

Yeast cells can perform post-translational modifications such as glycosylation, which bacteria cannot.

Question 18

In situ hybridization is used to:

Accepted Answer

Identify the location of specific mRNAs in intact organisms using fluorescent probes

Question 19

Which equation describes the relationship between the migration distance ($$d) of a $$DNA fragment in gel electrophoresis and its length ($$L$$)?

Accepted Answer

$$d \propto \frac{1}{L}$$

Question 20

A scientist wants to screen a DNA library for a clone carrying a gene of interest. Which technique should they use?

Accepted Answer

Nucleic acid hybridization with a labeled probe

Chapter 20: Biotechnology – DNA Libraries, Gene Cloning, and Analysis

Study Guide - Practice Questions