Q: If a PCR reaction starts with 2 molecules of DNA, how many molecules will there be after 4 cycles, assuming 100% efficiency?

$$2 \times 2^4$ = 32$$ molecules

Question 1

Which of the following best describes the function of restriction enzymes in genetic engineering?

Accepted Answer

They cut DNA at specific nucleotide sequences, allowing scientists to isolate or insert genes.

Question 2

A scientist wants to amplify a specific segment of DNA from a small blood sample to diagnose a genetic disorder. Which technique should they use, and what is the key enzyme involved?

Accepted Answer

Polymerase chain reaction (PCR); DNA polymerase

Question 3

During PCR, why is it necessary to heat the reaction mixture to 95°C at the beginning of each cycle?

Accepted Answer

To denature the DNA strands, separating them for primer binding

Question 4

If a PCR reaction starts with 2 molecules of DNA, how many molecules will there be after 4 cycles, assuming 100% efficiency?

Accepted Answer

$$2 	imes 2^4$ = 32$$ molecules

Question 5

Which of the following is a real-world application of DNA microarray technology?

Accepted Answer

Simultaneously measuring the expression levels of thousands of genes in a cancer cell

Question 6

A patient is suspected of having sickle cell anemia, a disease caused by a single nucleotide change in the beta-globin gene. Which technique would best allow a laboratory to detect this mutation?

Accepted Answer

Gel electrophoresis after restriction enzyme digestion

Question 7

Which of the following statements about genetically modified (GM) organisms is CORRECT?

Accepted Answer

GM organisms can be engineered to express traits such as herbicide resistance or improved nutrition.

Question 8

A forensic scientist is analyzing a DNA sample from a crime scene using short tandem repeats (STRs). Why are STRs useful for this purpose?

Accepted Answer

STRs are highly variable among individuals, allowing for unique DNA profiles.

Question 9

Which of the following best explains why bacteria are commonly used in recombinant DNA technology?

Accepted Answer

Bacteria can rapidly reproduce and express foreign genes inserted into plasmids.

Question 10

A gene therapy trial involves inserting a normal allele of a gene into bone marrow cells of a patient with a genetic disorder. What is a major risk associated with this approach?

Accepted Answer

The inserted gene may be expressed at the wrong time or in the wrong amount.

Question 11

Which of the following is a key ethical concern regarding the use of genetically modified (GM) crops?

Accepted Answer

GM crops may cross-pollinate with wild relatives, potentially spreading modified genes.

Question 12

A scientist uses a radioactive, single-stranded DNA probe in a Southern blot. What is the purpose of this probe?

Accepted Answer

To bind to a complementary DNA sequence and allow detection of a specific gene

Question 13

Which of the following best describes the process of gene cloning using a plasmid vector?

Accepted Answer

A gene of interest is inserted into a plasmid, which is then introduced into bacteria to replicate and express the gene.

Question 14

Which of the following is a potential benefit of using DNA microarrays in cancer research?

Accepted Answer

They can identify which genes are over- or under-expressed in tumor cells compared to normal cells.

Question 15

A restriction enzyme recognizes the sequence 5'-GAATTC-3'. If a mutation changes the sequence to 5'-GAGTTC-3', what is the most likely outcome?

Accepted Answer

The restriction enzyme will not recognize or cut the mutated site.

Question 16

Which of the following is a reason why PCR is a powerful tool in forensic science?

Accepted Answer

PCR can amplify tiny amounts of DNA from crime scene evidence for analysis.

Question 17

In gel electrophoresis, DNA fragments are separated based on which property?

Accepted Answer

Their size (length of the DNA fragments)

Question 18

Which of the following best explains why a DNA fingerprint produced by STR analysis is unique to an individual (except identical twins)?

Accepted Answer

The number and length of STR repeats at multiple loci vary greatly among individuals.

Question 19

A researcher wants to determine if a patient has a genetic predisposition to a certain disease by analyzing single nucleotide polymorphisms (SNPs). Which technique would be most appropriate?

Accepted Answer

DNA microarray analysis

Modern DNA Technology: Methods, Applications, and Implications

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