Microbiology Final Exam- BIO-330 UNCW

Relative increase in image size

magnification

The ability to distinguish two points that are close together

resolution

The ability to detect objects against a background

contrast

Sets limit of resolution

light quality

One advantage of phase-contrast microscopy is what?

The cells can be alive

Fluorescence microscopy is similar to using stains in regards to improving what?

contrast

If you needed to observe internal subcellular structures that are smaller than 100 nanometers, which technique would be most appropriate?

Transmission Electron Microscopy

If you needed to observe the relative location of two large proteins simultaneously inside a living cell, which technique would be most appropriate?

Fluorescence Microscopy

If you wanted to compare two bacteria that are suspected to be closely related, then what would be the least effective method?

Numerical taxonomy based on their ability to use different carbon sources.

A good molecular chronometer would be one that:

As time passes, bacterial accumulate mutations and the sequence of the molecular chronometer slowly changes.

Which of the following is true about the 16S rRNA gene?

You can find the 16S rRNA gene in mitochondria.

A ___________ acts as a benchmark for taxonomy, especially if determining what species a particular bacterium belongs to.

Type strain

Based on their label alone, you can say that E. coli O2:H7 and E. coli O157:H7 are the same species but are different what?

Serovars

For a structural polysaccharide, like those found in cell walls, you would expect that most of the monosaccharides are linked via what type of linkage?

Beta (β) linkages

In general, RNA is much more stable than DNA because it is a simpler molecule.

False

New nucleotides are added to what end of DNA?

3'

In total, there are how many possible amino acids?

nearly 200 million

__ form sugars and __ form amino acids are more commonly important for biological life on Earth

D, L

In a typical bacterial cell, most of the dry weight is from what?

proteins

What type of molecule can a bacterium use to stabilize its membrane at high temperatures?

Hopanoids

What type of linkages would you expect between the NAM and NAG monosaccharides in peptidoglycan?

Beta linkages

What enzyme is important for peptidoglycan cross-linking?

Transpeptidase

Vancomycin is effective at blocking peptidoglycan cross-linking by binding what?

D-alanine

Teichoic acid in Gram-positive bacteria and the O-antigen in Gram-negative bacteria both create a protective charge barrier to protect the cell against some chemicals.

False

__ cells have a thicker peptidoglycan layer; have no outer membrane

Gram positive

__ cells are surrounded by a secondary outer membrane containing endotoxin lipopolysaccharide; have a thin peptidoglycan cell wall,

Gram negative

Membrane invaginations are closed-off completely.

False

Biofilm formation is more dependent on the production of which of the following?

EPS

The __of bacteria are typically anchored to the cell

capsule

while a ____ is loosely associated but both structures are made of extracellular polysaccharides (EPS).

slime layer

Which mode of bacterial motility would you expect to have on a dry surface?

twitching

On a bacterium with a __ flagellar organization, you would expect a flagellum on both poles of the bacterium

amphitrichous

on a lophotrichous arrangement you would expect

multiple flagella at one pole

What would be the analogous structure of MotB be in a sodium (Na+) dependent bacterial flagellum?

PomB

In bacteria, rotation of the flagellum counter-clockwise (CCW) will result in a tumble.

False

In response to a recent increasing gradient of a chemoattractant, you would initially expect what?

A decreased occurrence of tumbles

In response to being exposed to the same chemoattractant for a while, you would expect what?

An increase in tumble frequency

If CheY was no longer functional, you would expect what?

The flagellum running CCW, as the flagellar motor is inherently biased towards a counterclockwise rotation

If CheR was no longer functional, what would you expect?

CheY dephosphorylation

MCP methylation is important for the chemotaxis system's what?

adaptation

Bacterial cells go through a process called meiosis, which results in 2 daughter cells.

False

A mutation (loss of function) in minD would also result in a loss of function of what?

MinC

A loss of function in which of these choices is not always lethal?

MinD

For a pre-existing culture of a bacterial species, what measurement method would require more culturing (growth)?

viable counting

In a batch culture, you would expect optical density to be increasing when measured with a spectrophotometer in what phase?

log phase

For a hyperthermophile, at what temperature would you expect its proteins to function properly at?

80 degrees C

A extremophile organism would be one that would synthesize everything from basic precursors

prototrophic

A fastidious would require many specific compounds to grow.

fastidious

If FtsZ stopped functioning in a bacterial cell, the cell would eventually die.

True

In the depiction of a bacterial growth curve, which phase is the growth rate greater than the death rate?

log phase (phase 2)

In the bacterial growth curve, which phase has little to no growth or death?

lag phase (phase 1)

How do cells typically lower the activation energy of a reaction?

enzymes

Because of the proton motive force, in most bacterial cells there is an overall ___ on the cytoplasmic (inside) side of the cell membrane and a ___ on the periplasmic (outside) side of the membrane.

negative charge, positive charge

From our discussion in class, in regards to Chlamydia trachomatis being unable to make it's own ATP, which of the follow would be most useful for this pathogen in regards to ATP?

ATP/ADP antiporter

In general, what is the primary function of the pentose phosphate pathway?

Rearrange sugars into more useful forms

What is the net output of glycolysis from one glucose molecule?

2 ATP, 2 NADH, and 2 pyruvate

The main purpose of fermentation is to do what?

Regenerate the NAD+ pool

In a typical chemoorganoheterotroph, what would be the likely consequence of inhibiting the function of quinones?

A significant loss of proton gradient

For lithotrophic organisms, substrates like hydrogen gas, sulfide, and iron can be used to___, however, __is the least efficient at this.

donate electrons to regenerate NADH, iron

For cyclic phototrophy ___ is the original electron donor, while terminal electron acceptor is what?

The reaction center

How does an organism generate NADH during oxygenic acyclic phototrophy?

By using a secondary photosystem

Sigma factors are essential for what?

RNA polymerase binding

Where do sigma factors bind?

The -35 and -10 elements

In the Lux operon (quorum sensing), LuxR acts as a what?

activator

In the Lac operon, if the operator site is mutated (loss of function), then what would occur?

The Lac operon will be turned on when glucose is not present

For a repressor, you would expect it to block what?

The promoter region of the DNA

In a two-component system the HK is phosphorylated on a specific __ residue with a phosphate taken from ATP, while the RR is phosphorylated at a specific __ residue with a phosphate from the HK

histidine, aspartate

Riboswitches and sRNAs typically will stop what process?

translation

There is only one type of sigma factor in a cell, however, that single type depends on the bacterial species

False

DnaA

binds to the origin of replication and is responsible for the initial steps in unwinding the helix

initiation

binds oriC

DNA polymerase III

Elongates a new nucleotide strand from the 3'-OH group provided by the primer

Tus

termination

Topoisomerase IV

Introduces single-stranded break into concatenated chromosomes to release them from each other, and then reseals the DNA

*Decatenation

Mutations in which molecules would have the most significant consequence?

DNA

Mutations from DNAP III (DNA polymerase III) occur more frequently from base mismatches than slipped strand mispairing

False

Which of the following mutations would be the least detrimental?

Silent mutation

Which of the following point mutations results in premature stop in translation?

nonsense mutation

DNAP III can fix base mismatches during replication using what?

3' - 5' exonuclease activity

The methyl-directed mismatch repair (MMR) system recognizes base mismatches how?

Physical distortions to DNA helix

The UvrABC system would more likely be fixing mutations from

mutagen damage

Which of the following enzymes would be the least useful in a response to massive amounts of DNA damage from a mutagen?

-DNA polymerase III

-DNA polymerase I

-DNA polymerase IV

-UvrABC

DNA polymerase III

Holiday junctions are resolved using which proteins?

ruvABC

A bacteriophage would likely switch from a lysogenic to a lytic life cycle when?

After activation of RecA

Trying to determine the unknown genotype (gene responsible) of a known phenotype (physical characteristic) of a bacterium would be reverse genetics.

False

If you were checking bacterial isolates for acquired antibiotic resistance by plated them on growth media with antibiotics (i.e. what you want will survive), this would be a type of what?

positive selection

If you were checking bacterial isolates for lost antibiotic resistance by plating them on growth media with antibiotics (i.e. what you want would die), this would be a type of what?

negative selection

LacZ and GFP are examples of reported proteins, these is typically used for what?

Differential screen

A recombinant plasmid is a bacterial plasmid that has DNA from another species inserted into it.

True

Heat shock and electroporation are variants of what bacterial process?

Transformation

Using homologous recombination for genomic engineering/mutagenesis can only be performed using plasmids.

False

What bacterial protein is essential for bacterial recombination?

RecA

Which of these proteins are not part of the CRISPR-Cas9 system?

RecA

Proteins in CRISPR-Cas9 system:

tracrRNA

protospacers

cas proteins

What natural repair mechanism in eukaryotes is utilized with CRISPR-Cas to allow for targeted mutation?

Non-homologous end joining

Which of the following would you not expect to find in a viral particle?

ATP synthase

Which of the forms of viral shedding usually results in immediate host cell death?

apoptosis

Which of the viruses in the following Baltimore classification groups would not likely need viral-derived RNA polymerases upon infection according to the table discussed in class?

Group I

Which virus-derived enzyme is important for Group VI and VII viruses to polymerize DNA from RNA templates?

reverse transcriptase

What type of immunity can be attributed to vaccination?

Artificial active immunity

Whole-cell vaccines always use live microbes.

False