AP-Micro (Microbiology) Microbial Genetics 1 — Questions and Answers
Question 1: What is the process called when bacteria take up naked DNA from their environment?
- Conjugation
- Transformation (Correct answer)
- Transduction
- Replication
Correct answer: Transformation
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?
- RNA Polymerase
- DNA Polymerase (Correct answer)
- Helicase
- Ligase
Correct answer: DNA Polymerase
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?
- Store energy
- Facilitate protein synthesis
- Carry genes for survival advantages (Correct answer)
- Serve as the primary genetic material
Correct answer: Carry genes for survival advantages
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?
- Bacteria produce spores
- DNA is transferred through a pilus (Correct answer)
- DNA is packaged in a virus and transferred
- Bacteria absorb nutrients
Correct answer: DNA is transferred through a pilus
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?
- Mutation (Correct answer)
- Transduction
- Replication
- Transcription
Correct answer: Mutation
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-Micro (Microbiology) Microbial Genetics 1
What is the process called when bacteria take up naked DNA from their environment?