Microbio Lab Exam 1

order these: nm mm um

from smallest to largest

nm, um, m

order: fungi, protozoa, virus, and bacteria

from smallest to largest

virus, bacteria, protozoa, fungi

what microbe is this

virus

what microbe is this

bacteria

what microbe is this

protozoa

what microbe is this

fungi

what characteristic might fungi have

hyphae

which microbe requires a host cell to replicate their genomes

viruses

which microbes may be multicellular

fungi

which ones have a cell wall

bacteria (peptidoglycan) and fungi (chitin)

which ones have organelles

protozoa and fungi

what is procedure for streaking for isolation

1. label cultures

2. mix the broth culture by flicking the eppendorf tube with your finger several times

3. Flame your inoculating loop, then aseptically remove a loopful from the broth culture tube labeled “MIX”; streak the loopful in a line (going back and forth), then streak across the first quadrant of the TSA plate to the next to connect them
   (just barely)

4. between each quadrant flame the loop and continue to streak plate as did in 3 (DO NOT GET MORE culture)

5. do until all 4 quadrents are done (do not connect quadrant 4 and 1)

6. flame loop

why do we streak for isolation

to isolate a cell (by diluting the sample that creates a lawn)

define a colony

a group of genetically identical cells that are derived from the same mother cell

what does a fungi colony look like

hairy

what does a bacteria colony look like

perfectly circular

The ability to prepare and maintain cultures that are completely pure and contamination-free requires what

Good aseptic technique, Correct streaking for isolation, Proper flaming of your loop

which gram stain has LPS/which color

gram negative, red

which gram stain has LTS/which color

gram positive, purple

what cell wall do gram negative bacteria have

thin and multiple

what cell wall do gram positive bacteria have

thick, 1 wall

what do cocci look like

circles

what doe bacilli look like

pills, long cylindrical

what do vibrio look like

c or comma shapped

which is obligate aerobe

a

which is obligate anaerobe

b

which is facultative anaerobe

c

which is aerotolerant anaerobe

d

what does obligate aerobe mean

cannot grow if no O2

what does facultative anaerobe mean

can grow with out without O2 but do better with O2

what does aerotolerant anaerobe mean

O2 has no effect on growth

what does obligate anaerobe mean

cannot grow if there is O2

which ones can produce gas within the agar

2, 3, 4

which one is a facultative anaerobe

3

which one will die if exposed to O2

2

what is a countable plate (for bacteria)

has 20-200 colonies

which plate is countable

40

how many CFU/ml are in original inoculum

4×10^6 CFU/ml

How do you get how many CFU/ml are in original inoculum

1. put 40 in scientific notation: 4×10^1

2. then for each vial add to the 1, including the origianl beaker

3. so since 5 in this example, add 5+1=6

4. final answer: 4×10^6 CFU/ml

what are viruses

nonliving, packages of protein and genetic material, requiring host cells for their replication

what genetic material do viruses use

DNA or RNA

what is a capsid

shell made of interlocking proteins

what are optional components in viruses

1. envelope: membrane on outside of capsid, not all viruses have one (no envelope=naked)

2. enzymes: packaged with viruses ex RT or RDRP

what are different capsid symmetry/shapes

1. helical

2. icosahedral

are there any clinically relevant naked helical viruses

no

what is this viruses shape/envelope status

enveloped icosahedral

what is this viruses shape/envelope status

helical enveloped

what is this viruses shape/envelope status

naked icosahedral

what does the genome in viruses look like (all different ways it can exist)

1. DNA or RNA

2. linear or circular

3. segmented or non-segmented

4. single or double stranded

5. negative or positive sense

what is RDRP enzyme

RNA-dependent RNA polymerase, necessary for production of virus genome and proteins in negative sense viruses

what is RT enzyme

reverse transcriptase, necessary for formation of DNA from RNA in retroviruses

why do some viruses have no enzymes

they don’t need them, ex: positive sense viruses

what is an acute viral infection

rapid and self-limiting, virus causes symptoms quickly after infection but is recognized and cleared by immune system (ex: influenza virus)

what is a persistent viral infection

initial infection is not cleared by immune system, and low viral numbers remain in body, can last months or years at low levels, then another infection occurs later in life, characterized by high viral numbers (ex: HIV)

what is a latent viral infection

virus infects host and is cleared, but its genome remains within host cells, months/years later, second infection occurs and is characterized by high viral numbers (ex: Herpes/cold sores)

what is the central dogma theorem

DNA→ RNA→ Protein

what is Transcription

DNA to RNA

DNA bases: A, T, C, G

RNA: all same but U instead of T

promoter

terminator

What is translation

mRNA to protein

ribosome: translates 5’ to 3’

start codon (5’AUG3’)

stop codon (5’UAA/UGA/UAG3’)

how many operons

how many promoters/terminators

how many genes

how many start/stop codons

3

4

8

8

which amnio acid will be the final one in the protein?

CCG

what is the zone of inhibition

B

what is the disk with the lowest concentration of triclosan

G

what can you tell about colony C (of triclosan)? and why

it is triclosan resistant, because it is growing inside the zone of inhibition

what is a point mutation

a single nucleotide is changed to a different nucleotide (ex: silent, missense, and nonsense)

what is a silent mutation

new codon codes for same amino acid (protein functions normally)

what is a missense mutation

new codon codes for new amino acid (protein may or may not function properly)

what is a nonsense mutation

new codon codes for a stop codon ends protein early (protein will not function properly)

what is frameshift mutation

a base is added to or deleted from the sequence, changing reading frame so every amino acid that follows is incorrect (protein will NOT function properly)

what does the yellow and pink tell us

yellow: negative for beta-lactamase

pink: positive for enzyme

what MIC is indicated by this broth dilution assay

64

if the isolate has a MIC of 5 which tubes will still show bacterial growth

0-4

what is the MIC indicated by this E-test

0.25

Standards for this organism consider less than or equal to 0.5 to be sensitive and greater than 0.5 to be resistant, is it likely that this patient can be successfully treated with ampicillin?

yes, MIC is below 0.5

what does kirby-bauer test for

susceptibility to antibiotics based on inhibition zone diameter

(antibiotics act on specific bacterial components, antibiotics are used to treat an infected host)

what do disinfectants do

disinfectants can be analyzed by zone of inhibition (kirby-bauer)

disinfectants act non-specifically on a large group of components (such as lipids of plasma membranes)

disinfectants are used to control organisms before host entry

which disinfectant is most effective against this organism

chlorine

which disinfectant is least effective against this organism

quats