Microbiology InQuizitive Chapter 8: Bacterial Genetics and Biotechnology

What is the name of a virus that infects bacteria?

bacteriophage FEEDBACK: Bacterial viruses are also known as phages.

Match each mutation to the type of cellular repair mechanism that fixes it.

base excision repair: a single damaged base SOS repair: (1) multiple deletions in an operon (2) DNA insertions of more than 15 base pairs (3) more than 20 base mismatches in a single region methyl mismatch repair: one or two base mismatches

An operon is transcribed only when mannitol concentrations are high and glucose concentrations are low. This operon is under what type(s) of control?

both positive and negative control

Please match each type of horizontal gene transfer with its description.

conjugation: DNA transfer via direct cell-cell contact transformation: uptake of free environmental DNA transduction: phage-mediated uptake of DNA

Match each statement to the correct step of translation.

elongation: (1) GTP hydrolysis drives formation of peptide bonds. (2) Peptide bond forms between amino acids. (3) tRNA leaves from the E site. initiation: (1) 30s subunit of ribosome binds to mRNA. (2) 50s subunit of ribosome binds to mRNA. termination: release factor enters the A site.

What type of mutation converts a codon to a stop codon?

nonsense

What is the difference between an F factor and an F-prime (F') factor?

only a F' factor contains host DNA

What are small extrachromosomal pieces of DNA found in bacteria?

plasmids

Match each type of RNA to its function.

sRNA: regulate gene expression mRNA: carry the information encoded in DNA tRNA: carry individual amino acids to the ribosome rRNA: provide ribosomal structure

Which of the following techniques is the slowest?

sequencing an entire genome

Strains of the pathogen Haemophilus influenza have been compared in the image here. Click on the two most divergent strains of Haemophilus influenzae.

As these lines become more separated, the genetic sequence of the 16s rDNA (ribosomal DNA) become more different. The lines closet together are the most closely related, and those that are further apart are less closely related. ANSWER: 1st top box last bottom box

Bacterial and eukaryotic transcription and translation are different. Match each statement with the type of cell it describes.

BACTERIAL TRANSCRIPTION AND TRANSLATION: (1) Transcription and translation are coupled. EUKARYOTIC TRANSCRIPTION AND TRANSLATION: (1) Introns are removed from mRNA before translation. (2) In general, promoters drive the expression of single genes. (3) Genomes contain a large amount of non-coding DNA.

Recombinant DNA is used in which of these situations?

CORRECT ANSWER(S): (1) A protein-based vaccine (like the HPV vaccine) is produced in yeast. (2) Mammalian genomes are modified using gene therapy. (3) Human insulin is produced in Escherichia coli. INCORRECT ANSWER(S): Pathogens exchange DNA in a patient.

Which of the following is true about bacterial DNA replication?

CORRECT ANSWER(S): (1) Bacterial DNA replication proceeds along two replication forks. (2) Bacterial DNA is supercoiled by DNA gyrase. (3) DNA replication is semiconservative. INCORRECT ANSWER(S): (1) Bacterial DNA replication is very inaccurate, with an error rate of 1 every 1000 bases. (2) Bacterial DNA replication proceeds in one direction along the chromosome.

Identify what is moved from the donor cell to the recipient cell during conjugation.

CORRECT ANSWER(S): (1) F factor (2) OriT (3) DNA transfer complex INCORRECT ANSWER(S): (1) DNA polymerase (2) bacterial chromosome

Doctors and dentists sometimes use this method to determine the causative age of an infection.

CORRECT ANSWER(S): (1) PCR (2) DNA hybridization (3) ribotyping INCORRECT ANSWER: (1) recombinant DNA

How are DNA mutations during replication caused?

CORRECT ANSWER(S): (1) UV radiation fusing base pairs (2) error made by DNA polymerase (3) chemical agents intercalating between base pairs INCORRECT ANSWER(S): induced agents that alter cellular phenotype

How do bacterial pathogens evade the immune response?

CORRECT ANSWER(S): (1) allowing a high rate of mutation (2) altering gene expression patterns INCORRECT ANSWER(S): (1) excreting inducer molecules (2) enhancing their phenotype through high mutation rates

Which of the following advantages do bacteria gain by structuring their genes in operons?

CORRECT ANSWER(S): Bacteria rapidly respond to changing environments. INCORRECT ANSWER(S): (1) Each gene can be transcribed with pinpoint accuracy. (2) Genes are individually regulated.

Which of the following are examples of vertical gene transfer?

CORRECT ANSWER(S): cell division INCORRECT ANSWER(S): (1) transformation (2) transduction (3) conjugation

Which methods of DNA transfer require a plasmid?

CORRECT ANSWER(S): conjugation INCORRECT ANSWER(S): (1) cell division (2) transduction (3) transformation

Which of the following techniques is used by researchers to drive DNA into bacterial cells?

CORRECT ANSWER(S): electroporation INCORRECT ANSWER(S): (1) DNA sequence alignment (2) restriction endonuclease digestion (3) probabilistic indicator

Non-typable strains of a pathogen, such as Haemophilus influenzae, lack distinct sugar coating that are usually used to identify them. How are clinical non-typable isolates easily identified?

CORRECT ANSWER(S): ribotyping INCORRECT ANSWER(S): (1) sequencing an entire genome (2) gel electrophoresis

Which of the following are true about bacterial genomes?

CORRECT ANSWER: They primarily encode genes, also called coding regions. INCORRECT ANSWER(S): (1) They are always on chromosomal DNA. (2) They are always circular.

Place the following events in order to construct a recombinant plasmid.

(1) Cut plasmid and foreign DNA with restriction enzymes. (2) Anneal or hybridize sticky ends of DNA together. (3) Ligase seals the backbone of the DNA molecule.

Identify the characteristics that belong to generalized transduction, specialized transduction, or both.

(1) specialized transduction: *requires a prophage *viral capsid carries both viral and host DNA (2) both: *can result in a new trait for the second host cell *uses bacteriophages (3) generalized transduction: *viral capsid carries only host DNA

A DNA mutation that changes the codon TAT to TAA causes a premature stop in the translation of the protein.

True

Identify which regions are found on the mRNA strand and which are not.

FOUND ON THE mRNA STRAND: (1) ribosome-binding site (2) start codon NOT FOUND ON THE mRNA STRAND: (1) polymerase binding site (2) promoter

Certain strains of microbes are called mutators because their DNA replication process eliminates mutations.

False

Okazaki fragments are produced in circular chromosome replication at only one of the two replication forks.

False

Restriction enzymes cut DNA at random sequences.

False

Silent mutations will affect both genotype and phenotype.

False

When a repressor protein binds a bacterial operon's promoter, only some of the genes within the operon are transcribed.

False

All genes in an operon are regulated by a single promoter.

True

In this image, the phage genome is purple, and the hose genome is gray. Click on one transducing phage.

Transducing phage particle injects host DNA into new cell, where it may recombine into the chromosome. On the image the phage that is pointing away from the clusters of phages

Match the examples of genetic regulation with each type of transcriptional control.

When the complex binds to the operon, a target gene is transcribed. (RIGHT-SIDE) When the complex binds to the operon, no target gene is transcribed. (LEFT-SIDE)

What does this image depict?

a composite transposon image shows: IS element 10, Tetracycline resistance and IS element 10 FEEDBACK: Composite transposons include sequences (such as the tetracycline resistance gene depicted) in addition to insertion sequences (IS).