Q: Given the DNA template strand sequence $$5'\text{-}TACTCTAGCGGTATC\text{-}3'$$, what is the corresponding mRNA sequence?

$$5'\text{-}AUGAGAUCGCCAUAG\text{-}3'$$

Question 1

Which of the following best describes the difference between DNA and RNA at the molecular level?

Accepted Answer

DNA contains the sugar deoxyribose and thymine, while RNA contains ribose and uracil.

Question 2

Given the DNA template strand sequence $$5'	ext{-}TACTCTAGCGGTATC	ext{-}3'$$, what is the corresponding mRNA sequence?

Accepted Answer

$$5'	ext{-}AUGAGAUCGCCAUAG	ext{-}3'$$

Question 3

A mutation changes a codon from UAU (tyrosine) to UAA. What type of mutation is this, and what is its likely effect?

Accepted Answer

Nonsense mutation; introduces a premature stop codon

Question 4

Which of the following is a likely consequence of a frameshift mutation?

Accepted Answer

The reading frame is altered, resulting in a completely different and often nonfunctional protein.

Question 5

Which enzyme is responsible for synthesizing the complementary DNA strand during replication?

Accepted Answer

DNA polymerase

Question 6

A bacterium acquires a gene for antibiotic resistance from a dead cell in its environment. What is this process called?

Accepted Answer

Transformation

Question 7

Which of the following best describes the role of the F pilus in bacterial conjugation?

Accepted Answer

It forms a bridge between donor and recipient cells for plasmid transfer.

Question 8

A chemical mutagen that resembles a normal nucleotide and can be incorporated into DNA, but pairs incorrectly during replication, is called a:

Accepted Answer

Nucleotide analog

Question 9

Which of the following statements about plasmids is TRUE?

Accepted Answer

Plasmids can carry genes that confer survival advantages, such as antibiotic resistance.

Question 10

If a mutation changes the DNA sequence from $$5'	ext{-}TAC	ext{-}3' to$$ $$5'	ext{-}TAT	ext{-}3'$$, and both code for tyrosine, what type of mutation is this?

Accepted Answer

Silent mutation

Question 11

Which of the following is NOT a requirement for a piece of DNA to be successfully expressed in a recipient bacterial cell after horizontal gene transfer?

Accepted Answer

It must be linear and lack any regulatory sequences.

Question 12

Which process involves the transfer of bacterial DNA from one cell to another via a bacteriophage?

Accepted Answer

Transduction

Question 13

A researcher exposes bacteria to UV light, resulting in the formation of thymine dimers. What is the most likely effect if these dimers are not repaired?

Accepted Answer

Errors during DNA replication, leading to mutations

Question 14

Which of the following best explains why a single base insertion in a coding region can have a more severe effect than a single base substitution?

Accepted Answer

A base insertion causes a frameshift, altering all downstream codons.

Question 15

Which of the following is an example of horizontal gene transfer?

Accepted Answer

A bacterium acquiring a plasmid from another bacterium via conjugation.

Question 16

A pathogenicity island is best described as:

Accepted Answer

A cluster of genes acquired by horizontal gene transfer that contribute to a bacterium's ability to cause disease.

Question 17

Which of the following best describes the outcome of an Hfr × F− conjugation event?

Accepted Answer

The recipient receives chromosomal genes from the donor, but usually remains F−.

Question 18

Which of the following is a direct result of a missense mutation?

Accepted Answer

A codon is changed, resulting in a different amino acid in the protein.

Question 19

Which of the following best explains why bacteria can rapidly adapt to new environments?

Accepted Answer

They can acquire new genes through horizontal gene transfer mechanisms such as transformation, conjugation, and transduction.

Question 20

A scientist uses electroporation to introduce a plasmid into a bacterial cell. What is the main effect of the electrical pulse in this process?

Accepted Answer

It creates temporary pores in the membrane, allowing DNA to enter.

slides 10 - Microbial Genetics: Structure, Mutation, and Gene Transfer

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