Microbiology Final Study Guide (exam 2)

Viral replication occurs _____

Intracellularly

Restriction is ______

a defense host mechanism that prevents other viruses from entering the cell

The T4 bacteriophage could not infect staphalococcus areus because this bacteria does NOT possess a ____

lipopolysaccharide (LPS) outer membrane

A virus that kills its host cell is said to be _____

lytic or virulent

For bacteriophages and animal viruses _____ is the step in the viral life cycle that determines host cell specificity

attachment

When packaged in the viron, the complete complex of nucleic acid and protein is known as a virus ______

nucleocapsid

What would happen is a T4 bacteriophage did not contain lysozyme?

It would be unable to penetrate the host cell wall

You perform a plaque assay by mixing melted agar with 1ml liquid culture containing bacteriophage Petrie plate. After incubation, the plate is completely clear. What is the most likely explanation?

The phage concentration was so high that all the host bacterial cells were killed

According to the wobble hypothesis, pairing can occur when

the codon and anticodon differ at the last base

How are plasmids different than chromosomes?

Plasmids contain genes that are NOT essential for cellular growth and replication

The precursor of each new nucleotide in a strand of DNA is a _____

deoxynucleoside 5’-triphosphate

Stop codons are also called ____ codons

nonsense

The flow of biological information begins with ____

DNA replication

Transcription of chaperones is greatly accelerated when a cell is stressed by

excess heat

You are studying a protein that you believe is a toxin produced by the Gram-negative bacterium Salmonella typhimurium whenever you attempt to purify the protein from lysed cell cultures, you get two forms of the protein. One form is smaller than the other and is missing 15 amino acids from the N-terminus compared to the larger form, this leads you to hypothesize that _______

the protein is secreted and folds outside of the cell

In DNA replication, there are leading and lagging strands because

DNA replication is semiconservative and each strand is copied in opposite directions

When arginine is added to a culture already growing exponentially in a medium without arginine, what occurs?

Growth continues, but the production of enzymes required for synthesis of arginine stop

Cyclic AMP is synthesized from ATP by on enzyme called ____, which is involved in ______

adenylate cyclase/ catabolite repression

Chemotaxis in bacteria occurs through the use of ________

a modified two-component system

If you found a high concentration of alarmonnes (ppGpp & pppGpp) in a bacterial cell, what could you conclude?

The cell was undergoing a stringent response and has been transferred to an environment with limited carbon source

Quorum sensing is a regulatory system that requires a certain cell density to work effectively. Each of the following activities utilizes quorum sensing EXCEPT _____

feedback inhibition

Which regulatory mechanism does NOT depends on a conformational change in protein/enzyme structure to change activity?

Attenuation

Which of the following is a characteristic of an isoenzyme?

The same reaction can be catalyzed by multiple enzyme variants

How is the activity of a riboswitch controlled?

Metabolite binding can change its structure

Multiple operons under the control of the one regulatory protein are called a(n) ____

regulon

A mutant that has a nutritional requirment for growth is an example of a(n) ______

auxotroph

Consider a mutation in which the change is from UAC to UAU. Both codons encode for the amino acid tyrosine, which type of point mutation is this?

Silent mutation

The uptake of free DNA from the environment is referred to as ___, while the transfer of DNA with a cell-to-cell contact is known as ____.

transformation/conjugation

You have a strain of E. coli that is missing the gene required to make the amino acid cysteine, but by transforming this E. coli with a plasmid that contains the WT gene, the bacteria can now produce cysteine. This process is called _____

complementation

The SOS regulatory system is activated by ____

DNA damage

You work for a biotechnology company that uses bacterial Streptomyces strains to produce pharmaceutical products. A phage has infected and kiled some of your Streptomyces strains during production, resulting in dramatically decreased yields. To protect the strains from infection you propose to _____.

design and insert CRISPR spacer sequences into the genomes of your strains that are complementary to the genomes of the phages that are infecting the cultures

The designation Phe-, Leu-, and Ser+ refer to an organism’s ______

phenotype

Why is transposon mutagenesis so useful?

Insertion of a transposon into a gene means the gene product is no longer made

Cells that have “insertional inactivation of the lacZ gene are _____

white

The differences between Southern blotting and Northern Blotting is that ______

Southern blotting uses a DNA target and Northern blottings uses an RNA target sequence

The genes encoding green fluorescent protein (GFP) and Beta-galactosidase are typically used in cloning as ______

reporter genes

Which time period(s) during PCR thermocycling is/are the hottest in temperature?

During DNA denaturation

The process in which similar/related DNA sequences from two different sources are exchanges is called _____

homologous recombination

True or false: Temperate viruses can enter into either a lytic or lysogenic cycle

true

True or false: Naked viruses have an envelope

false

True or false: Both DNA and RNA synthesis require an RNA primer to begin

False

True or false: Adenine and guanine are classifed as purines

true

True or false: Activators bind to operator regions of DNA

false

True or false: The genes encoded in the lactose operon encode for the enzymes required to metabolize

true

True or false: In specialized transduction, virtually any genetic marker can be transferred from donor to recipient

false

True or false: One method to avoid issues with introns when expressing a eukaryotic gene is a bacterium is to simply clone the mature transcript as cDNA

True

GroEL and GroES

Heat shock proteins that aid in protein folding

N-formylmethionine

The start codon for protein translation in bacteria encodes for this amino acid

Signal recognition particle (SRP)

Aids in transporting proteins that are destined for the cytoplasmic membrane

Exon

Coding regions of eukaryotic genes

Type 3 secretion system

Injects proteins (toxins) outside of the cell and into eukaryotic host cells; entire structure is called an “injectisome”

Sec System

Exports unfolded proteins and inserts integral membrane proteins

Type 4 excretion system

Most common; normally transfers DNA through conjugation

Type 6 secretion system

A cytoplasmic injector that forms a contractile sheath; used by bacteria as weapons to compete with other bacterial cells or to attack eukaryotic cells

Tat system

Transports folded proteins across membranes