Biology Microbiology and Biotechnology Flashcards

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

Answer: Conjugation

Conjugation is a form of horizontal gene transfer where a plasmid or chromosomal DNA passes from a donor to a recipient bacterium through a pilus.

What is the primary purpose of a vector in recombinant DNA technology?

Answer: To carry and replicate foreign DNA in a host organism

A vector (e.g., plasmid or viral vector) carries recombinant DNA into a host cell and allows it to replicate and be expressed.

Viruses that infect bacteria are specifically called:

Answer: Bacteriophages

Bacteriophages (phages) are viruses that specifically infect bacterial cells and can follow lytic or lysogenic replication cycles.

Which technique separates DNA fragments by size using an electric field?

Answer: Gel electrophoresis

Gel electrophoresis uses an electric field to migrate DNA through an agarose gel, with smaller fragments moving farther than larger ones.

What is the main difference between gram-positive and gram-negative bacteria?

Answer: Gram-negative bacteria have an outer membrane absent in gram-positive bacteria

Gram-negative bacteria have an additional outer membrane containing lipopolysaccharides (LPS), which the Gram stain cannot penetrate, causing the cells to appear pink/red.

In fermentation, what serves as the final electron acceptor?

Answer: An organic molecule

In fermentation, an organic molecule (such as pyruvate) serves as the final electron acceptor, regenerating NAD+ for continued glycolysis.

Which component of a retrovirus is responsible for converting its RNA genome into DNA?

Answer: Reverse transcriptase

Reverse transcriptase is the viral enzyme that synthesizes a DNA copy from the RNA genome of retroviruses such as HIV.