BIOL 200 EXAM 3 Old Qs

What does a negative RT-PCR result indicate?

It indicates that no RNA was present in the sample tested, suggesting that the individual did not have a viral infection.

What is transduction?

Transduction is the transfer of DNA from a donor to a recipient cell using a bacteriophage.

Which organisms can be transgenic?

Fungi, plants, bacteria, and mammals can all be transgenic, meaning they can express recombinant proteins from another species.

What is the significance of PCR product treated with restriction endonucleases?

The PCR product from Bacillus anthracis treated with restriction endonucleases from Escherichia coli would allow for the expression of a recombinant protein similar to that of Bacillus anthracis.

What are the three major steps in PCR?

1. Denaturation: High heat separates double-stranded DNA into single strands. 2. Annealing: Temperature is lowered to allow primers to bind to target sequences. 3. Extension: Temperature is raised for DNA polymerase to add nucleotides and build new DNA strands.

What is the polymerase chain reaction (PCR)?

PCR is a laboratory technique used to produce millions of copies of a specific DNA sequence.

What is the role of mRNA in protein synthesis?

mRNA (messenger RNA) carries the genetic blueprint from DNA in the nucleus to the ribosome for protein synthesis.

What is the role of tRNA in protein synthesis?

tRNA (transfer RNA) matches specific amino acids to the codons on the mRNA using its anticodon during protein synthesis.

What is the role of rRNA in protein synthesis?

rRNA (ribosomal RNA) forms the structural and catalytic core of the ribosome, where proteins are synthesized.

What is gel electrophoresis?

Gel electrophoresis is a laboratory method used to separate DNA fragments based on size.

What is the incubation period in infectious diseases?

The incubation period is the time after initial contact with an infectious agent but before the first symptoms appear.

What should be used on fomites for microbial control?

Disinfectants should be used on fomites for effective microbial control.

What is the decimal reduction time (D)?

The decimal reduction time (D) is the time required to kill 90% of the microbes in a sample with a given treatment.

What are bacterial exotoxins?

Exotoxins are secreted proteins, mostly from Gram-positive bacteria, that actively damage host cells or interfere with signaling. Example: Botulinum toxin.

What are bacterial endotoxins?

Endotoxins are the lipid A portion of lipopolysaccharides (LPS) in Gram-negative bacteria, released when the cell dies, triggering inflammatory responses. Example: Salmonella LPS.

What is the best way to reduce microbes on a non-living object?

Using bleach is one of the best methods to reduce the number of microbes on non-living objects.

What is a bacteriostatic agent?

A bacteriostatic agent is a chemical that prevents bacterial growth, inhibiting binary fission.

What is sterilization?

Sterilization is the removal or destruction of all forms of microbial life.

What are Koch's postulates?

Koch's postulates are a series of four criteria used to establish a causal relationship between a microbe and a disease.

What is an endemic disease?

An endemic disease is one that is constantly present in a given population.

What is an epidemic?

An epidemic is an outbreak of disease that occurs when the number of cases exceeds what is normally expected in a population.

What is a virulence factor?

A virulence factor is a characteristic of a microbe that enhances its ability to cause disease.

What is the role of antibiotics in microbial resistance?

Misuse of antibiotics can lead to or accelerate the evolution of drug-resistant microbes.

What is the significance of a large ID50 value?

A microbe with a large ID50 value is less pathogenic, as it requires a higher dose to infect 50% of the hosts.

What is a symptom of a disease?

A symptom is an effect of a disease (such as chills or pain) that is felt only by the affected person.

What is a sign of a disease?

A sign is an outwardly observable effect of a disease (such as coughs or fever).