Q: Which process correctly represents the central dogma of molecular biology in prokaryotes?

$$\text{DNA} \to \text{RNA} \to \text{Protein}$$

Question 1

Which of the following best describes the relationship between genotype and phenotype in bacteria?

Accepted Answer

The genotype is the genetic makeup that determines the phenotype, which is the observable characteristics.

Question 2

A mutation in the gene encoding for urease in Klebsiella prevents the enzyme from being produced. What is the most likely phenotypic result when this bacterium is grown on urea agar?

Accepted Answer

The bacterium will not change the color of the medium, indicating a urease-negative phenotype.

Question 3

Which process correctly represents the central dogma of molecular biology in prokaryotes?

Accepted Answer

$$	ext{DNA} 	o 	ext{RNA} 	o 	ext{Protein}$$

Question 4

A point mutation changes a codon from $$	ext{GAA} to$$ $$	ext{GAG}$$, both of which code for glutamic acid. What type of mutation is this?

Accepted Answer

Silent mutation

Question 5

Which of the following best explains why the genetic code is described as 'redundant'?

Accepted Answer

Multiple codons can code for the same amino acid.

Question 6

During bacterial conjugation, what is the role of the F (fertility) factor?

Accepted Answer

It enables the formation of a sex pilus and transfer of DNA to a recipient cell.

Question 7

A bacterium acquires a gene for antibiotic resistance via a plasmid. This is an example of:

Accepted Answer

Horizontal gene transfer

Question 8

Which mechanism of horizontal gene transfer involves the uptake of 'naked' DNA from the environment?

Accepted Answer

Transformation

Question 9

In Griffith's experiment with Streptococcus pneumoniae, what was the key finding that demonstrated transformation?

Accepted Answer

Live non-virulent bacteria became virulent after exposure to heat-killed virulent bacteria.

Question 10

Which of the following best describes a frameshift mutation?

Accepted Answer

A mutation caused by insertion or deletion of a base, altering the reading frame.

Question 11

A bacterium is exposed to a mutagen that causes the deletion of a single nucleotide in a gene. What is the most likely consequence for the encoded protein?

Accepted Answer

The protein will have a completely altered amino acid sequence downstream of the mutation.

Question 12

Which of the following is true about plasmids?

Accepted Answer

They are small, circular DNA molecules that replicate independently of the chromosome.

Question 13

What is the function of the RecA protein in bacterial cells?

Accepted Answer

It mediates homologous recombination between donor and recipient DNA.

Question 14

Which of the following statements about transposons is correct?

Accepted Answer

Transposons are mobile genetic elements that can move within and between DNA molecules.

Question 15

During generalized transduction, which of the following occurs?

Accepted Answer

A phage transfers random fragments of bacterial DNA to a recipient.

Question 16

A bacterial cell is made competent and takes up a DNA fragment containing a gene for ampicillin resistance. What must happen for the cell to express this new trait?

Accepted Answer

The DNA fragment must recombine with the bacterial chromosome or exist as a plasmid.

Question 17

Which of the following best describes vertical gene transfer?

Accepted Answer

Transfer of genetic material from parent to offspring during reproduction.

Question 18

A bacterium with an integrated F factor (Hfr cell) conjugates with an F- cell. What is the most likely outcome?

Accepted Answer

The F- cell remains F- but may acquire new chromosomal genes.

Question 19

Which of the following is a real-world consequence of horizontal gene transfer in bacteria?

Accepted Answer

Rapid spread of antibiotic resistance genes among pathogenic bacteria.

Question 20

Which of the following best explains why frameshift mutations are often more severe than point mutations?

Accepted Answer

Frameshift mutations change the reading frame, altering every amino acid downstream.

Microbial Genetics: Foundations, Gene Expression, and Mutation

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