Question 1

Which of the following best describes the role of dideoxynucleotides (ddNTPs) in Sanger (dideoxy) DNA sequencing?

Accepted Answer

They terminate DNA strand elongation by preventing the formation of a phosphodiester bond.

Question 2

In a Sanger sequencing reaction, why are chain-terminating nucleotides (ddNTPs) added at a lower concentration than normal deoxynucleotides (dNTPs)?

Accepted Answer

To allow for the generation of DNA fragments of varying lengths, each terminating at a different nucleotide.

Question 3

Which equation correctly represents the cost to sequence the entire human genome using Sanger sequencing, given that sequencing 1000 base pairs costs $4 and the human genome is approximately $10^9$ base pairs?

Accepted Answer

$\$4 	imes \frac{10^9}{1000}$

Question 4

Next generation sequencing (NGS) technologies, such as Illumina sequencing, differ from Sanger sequencing primarily because:

Accepted Answer

NGS sequences millions of DNA fragments in parallel by synthesis, greatly increasing throughput.

Question 5

Which of the following statements about gene expression is FALSE?

Accepted Answer

All genes encode a protein.

Question 6

A mutation makes the TATA box of a promoter more similar to the consensus sequence. What is the most likely effect on gene expression?

Accepted Answer

Transcription of the gene will increase, leading to higher levels of the gene product.

Question 7

Which of the following best explains how alternative splicing increases protein diversity?

Accepted Answer

It allows a single gene to produce multiple mRNA transcripts by including or excluding different exons.

Question 8

In eukaryotic transcription, which sequence element is typically found closest to the transcription start site?

Accepted Answer

TATA box

Question 9

Which of the following is a consequence of a mutation in a promoter that decreases its similarity to the consensus sequence?

Accepted Answer

Decreased binding of RNA polymerase, resulting in lower gene expression.

Question 10

Which of the following best describes the function of enhancers in eukaryotic gene regulation?

Accepted Answer

They increase the rate of transcription by providing binding sites for activator proteins.

Question 11

During transcription, which strand of DNA is used as the template for RNA synthesis?

Accepted Answer

The template strand

Question 12

Which of the following correctly matches the direction of RNA synthesis by RNA polymerase?

Accepted Answer

RNA is synthesized in the 5' to 3' direction.

Question 13

Which of the following is TRUE regarding the processing of eukaryotic mRNA?

Accepted Answer

Introns are removed and exons are joined together during splicing.

Question 14

A researcher isolates genomic DNA and mRNA from mouse cells and hybridizes them. In the resulting hybrid, which region corresponds to an intron?

Accepted Answer

A loop of DNA that does not hybridize with mRNA.

Question 15

Which of the following is a key difference between prokaryotic and eukaryotic promoters?

Accepted Answer

Eukaryotic promoters often contain a TATA box and are more complex, while prokaryotic promoters have -10 and -35 consensus sequences.

Question 16

Which of the following best explains why all cells in your body have (almost) identical DNA but different cell types have different phenotypes?

Accepted Answer

Gene expression is regulated so that different cell types express different sets of genes.

Question 17

Which of the following is a real-world consequence of a mutation in the promoter region of the gene encoding melanin synthesis?

Accepted Answer

Skin pigmentation may change, resulting in either lighter or darker skin depending on the effect of the mutation.

Question 18

Which of the following statements about exons and protein domains is correct?

Accepted Answer

In general, one exon encodes one protein domain.

Gene Expression, Transcription, and DNA Sequencing Methods

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