Question 1

Which of the following best describes a genetically-modified organism (GMO)?

Accepted Answer

An organism whose genome has been precisely modified by human intervention, including gene deletion, modification, replacement, or addition from the same or another species.

Question 2

Why is it necessary to use cDNA rather than genomic DNA when expressing a human gene in bacteria?

Accepted Answer

Bacterial cells lack the machinery to remove introns from eukaryotic genes, so cDNA (which is made from spliced mRNA and lacks introns) is required for proper expression.

Question 3

Which feature of a plasmid is essential for selecting bacteria that have taken up the plasmid during transformation?

Accepted Answer

Selectable marker, such as an antibiotic resistance gene

Question 4

Restriction enzymes are used in recombinant DNA technology because they:

Accepted Answer

Cut DNA at specific palindromic sequences, producing compatible ends for ligation.

Question 5

A plasmid with a lac promoter and an inserted human gene is used to produce insulin in E. coli. What is the role of the lac promoter?

Accepted Answer

It is an inducible promoter that enables controlled expression of the human gene, producing large quantities of protein only when an inducer is added.

Question 6

Which equation represents the relationship between the migration distance ($$d) of a $$DNA fragment in agarose gel electrophoresis and its size ($$s$$)?

Accepted Answer

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

Question 7

Which of the following is a major reason for the rapid expansion of antibiotic resistance in bacteria?

Accepted Answer

Natural selection acting on bacterial populations exposed to antibiotics.

Question 8

What is the function of DNA ligase in recombinant DNA technology?

Accepted Answer

It joins DNA fragments by repairing the sugar-phosphate backbone.

Question 9

Which of the following best explains why only bacteria with circular plasmids grow on ampicillin plates after transformation?

Accepted Answer

Circular plasmids contain the antibiotic resistance gene and are stably replicated, allowing survival on ampicillin plates.

Question 10

Which of the following statements about plasmids is FALSE?

Accepted Answer

Plasmids cannot replicate independently in bacterial cells.

Question 11

A restriction enzyme cuts the sequence $$5'\ GAATTC\ 3'$$ and $$3'\ CTTAAG\ 5'. $$What type of ends does this enzyme produce?

Accepted Answer

Sticky ends

Question 12

Which of the following is a real-world application of genetically-modified bacteria?

Accepted Answer

Producing human insulin for diabetes treatment.

Question 13

What is the purpose of the Shine-Dalgarno sequence in a bacterial expression vector?

Accepted Answer

It facilitates efficient translation by aligning the ribosome with the start codon.

Question 14

Which process allows bacteria to acquire antibiotic resistance genes from other bacteria?

Accepted Answer

Horizontal gene transfer via plasmid exchange.

Question 15

In blue/white screening, what does the presence of white colonies on X-gal plates indicate?

Accepted Answer

Bacteria containing recombinant DNA molecules that disrupt the lacZ gene.

Question 16

Which Nobel Prize-winning discovery enabled the creation of cDNA from mRNA?

Accepted Answer

Discovery of reverse transcriptase.

Question 17

Which equation best describes the Central Dogma of molecular biology, and how was it modified by the discovery of reverse transcriptase?

Accepted Answer

$$DNA \rightarrow RNA \rightarrow Protein$$; modified to $$RNA \rightarrow DNA by $$reverse transcriptase

Question 18

Which of the following is NOT a reason for the rise of multidrug-resistant bacteria?

Accepted Answer

Bacteria only acquire resistance through mutation and not through plasmid transfer.

Question 19

Which step is necessary to ensure the correct orientation of a gene insert in a plasmid for expression?

Accepted Answer

Digesting the plasmid with restriction enzymes and running the fragments on a gel to analyze band patterns.

Biotechnology and Recombinant DNA Technology: Principles and Applications

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