AP-Micro (Microbiology) Microbial Genetics

Question 1

What is the process called when bacteria take up naked DNA from their environment?

Accepted Answer

Transformation

Answer

Transformation is one of the three main mechanisms of horizontal gene transfer in bacteria. It involves a bacterial cell directly taking up 'naked' DNA fragments from its external environment. This acquired DNA can then be incorporated into the recipient cell's genome, potentially conferring new traits.

Question 2

Which enzyme is responsible for synthesizing new DNA strands during bacterial DNA replication?

Accepted Answer

DNA Polymerase

Answer

DNA polymerase is the key enzyme responsible for synthesizing new DNA strands during replication. It adds nucleotides one by one to the growing DNA chain, using an existing DNA strand as a template. While other enzymes like helicase and ligase are involved, DNA polymerase performs the actual polymerization of DNA.

Question 3

What is the role of plasmids in bacterial cells?

Accepted Answer

Carry genes for survival advantages

Answer

Plasmids are small, circular, extrachromosomal DNA molecules found in bacteria. They often carry genes that provide bacteria with advantageous traits, such as antibiotic resistance, virulence factors, or the ability to metabolize unusual compounds. These genes are not essential for basic survival but can significantly enhance a bacterium's fitness in specific environments.

Question 4

What happens during bacterial conjugation?

Accepted Answer

DNA is transferred through a pilus

Answer

Bacterial conjugation is a process of horizontal gene transfer where genetic material is directly transferred from one bacterial cell to another. This transfer typically occurs through a specialized appendage called a pilus (or sex pilus), which forms a bridge between the donor and recipient cells, allowing for the passage of plasmid DNA.

Question 5

Which term describes a change in the sequence of DNA in a microorganism?

Accepted Answer

Mutation

Answer

A mutation is a permanent, heritable change in the nucleotide sequence of an organism's DNA. These changes can range from a single base pair substitution to larger chromosomal rearrangements. Mutations are the ultimate source of genetic variation and can lead to new traits, some of which may be beneficial, harmful, or neutral.

AP Practice Test

AP Practice Test

AP-Micro (Microbiology) Microbial Genetics