Question 1

Which of the following best describes a genomic library?

Accepted Answer

A collection of clones carrying fragments of the entire genome inserted into vectors.

Question 2

What is the primary advantage of using a bacterial artificial chromosome (BAC) as a cloning vector?

Accepted Answer

BACs can carry large DNA inserts, allowing for cloning of large genomic fragments.

Question 3

A cDNA library differs from a genomic library in that:

Accepted Answer

It contains only the coding regions (exons) of genes expressed in the original cells.

Question 4

Which enzyme is essential for synthesizing cDNA from mRNA?

Accepted Answer

Reverse transcriptase

Question 5

In nucleic acid hybridization, what is the function of a probe?

Accepted Answer

To bind specifically to a complementary DNA sequence and allow identification.

Question 6

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

Accepted Answer

Bacteria lack the machinery to 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 repeating which three steps?

Accepted Answer

Denaturation, annealing, extension

Question 9

If you start with a single DNA molecule, how many copies will you have after 5 cycles of PCR? Use the formula $$N = 2^n$$, where $$n is $$the number of cycles.

Accepted Answer

32

Question 10

Gel electrophoresis separates DNA fragments based on:

Accepted Answer

Their length

Question 11

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

Accepted Answer

Comparing DNA molecules to detect sequence variations affecting 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 role of dideoxyribonucleotides (ddNTPs)?

Accepted Answer

They terminate DNA strand synthesis at specific bases.

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 advantageous over Northern blotting because:

Accepted Answer

It is quicker and more sensitive for detecting mRNA.

Question 16

In situ hybridization is used to:

Accepted Answer

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

Question 17

A scientist wants to express a mammalian gene that requires glycosylation for function. Which host cell should they use?

Accepted Answer

A mammalian cell

Question 18

Which of the following is a real-world application of restriction fragment analysis?

Accepted Answer

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

Question 19

If a restriction enzyme recognizes the sequence $$5'	ext{GAATTC}\ 3'$$ and a mutation changes it to $$5'	ext{GAGTTC}\ 3'$$, what will happen?

Accepted Answer

The restriction enzyme will not cut at the mutated site, resulting in a different fragment pattern.

Question 20

Which equation best describes the exponential amplification of DNA during PCR, where $$N is $$the number of DNA molecules after $$n$$ cycles?

Accepted Answer

$$N = 2^n$$

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

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