Q: If the spontaneous mutation rate is $1 \times 10^{-6}$ per base pair per replication, how many mutations would you expect in a population of $1 \times 10^{9}$ bacteria, each with a genome of $5 \times 10^{6}$ base pairs?

$5 \times 10^{9} \times 1 \times 10^{-6} = 5 \times 10^{3}$ mutations

Question 1

Which of the following statements correctly describes the difference between DNA and RNA nucleotides?

Accepted Answer

DNA nucleotides contain deoxyribose, while RNA nucleotides contain ribose.

Question 2

In a double-stranded DNA molecule, which base pairs with cytosine, and how many hydrogen bonds are formed between them?

Accepted Answer

Guanine; three hydrogen bonds

Question 3

A segment of DNA has the sequence 5'-AGTCGT-3'. What is the sequence of the complementary strand?

Accepted Answer

3'-TCAGCA-5'

Question 4

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

DNA helicase

Question 5

During DNA replication, what is meant by the term 'semi-conservative'?

Accepted Answer

Each new DNA molecule contains one parent strand and one new strand.

Question 6

Which process describes the flow of genetic information from DNA to RNA to protein?

Accepted Answer

Central Dogma

Question 7

In prokaryotes, what is a key difference in the location and timing of transcription and translation compared to eukaryotes?

Accepted Answer

Transcription occurs in the cytoplasm and translation begins before transcription is complete in prokaryotes.

Question 8

Which type of gene is only expressed when its product is needed, such as the enzymes for lactose metabolism in E. coli?

Accepted Answer

Inducible gene

Question 9

What is the role of the lac operon in E. coli?

Accepted Answer

It is an inducible operon that controls lactose metabolism.

Question 10

Which of the following mutations results in a premature stop codon, potentially truncating the protein product?

Accepted Answer

Nonsense mutation

Question 11

A chemical mutagen that closely resembles a normal DNA base and is incorporated into DNA during replication is called:

Accepted Answer

Base analog

Question 12

Which type of horizontal gene transfer involves the uptake of naked DNA from the environment by a competent bacterial cell?

Accepted Answer

Transformation

Question 13

A plasmid that carries multiple genes for antibiotic resistance is known as:

Accepted Answer

R-factor

Question 14

Which of the following best describes the effect of UV radiation on DNA?

Accepted Answer

It causes the formation of thymine dimers.

Question 15

If the spontaneous mutation rate is $1 	imes 10^{-6}$ per base pair per replication, how many mutations would you expect in a population of $1 	imes 10^{9}$ bacteria, each with a genome of $5 	imes 10^{6}$ base pairs?

Accepted Answer

$5 	imes 10^{9} 	imes 1 	imes 10^{-6} = 5 	imes 10^{3}$ mutations

Question 16

Which process involves the transfer of genetic material from one bacterium to another via a sex pilus?

Accepted Answer

Conjugation

Question 17

What is the function of tRNA during translation?

Accepted Answer

It carries amino acids to the ribosome and matches them to the mRNA codon via its anticodon.

Question 18

Which of the following is true about the genetic code?

Accepted Answer

The genetic code is degenerate, meaning multiple codons can encode the same amino acid.

Question 19

A frameshift mutation is most likely to result from which of the following?

Accepted Answer

Insertion or deletion of one or more nucleotides

Question 20

Which type of horizontal gene transfer requires a bacteriophage to mediate the transfer of DNA between bacteria?

Accepted Answer

Transduction

Microbial Genetics: Structure and Function of Nucleic Acids

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