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Microbiology > EXAM 2 P4 > Flashcards

EXAM 2 P4 Flashcards

1
Q

cell envelope

A

refers to everything surrounding the cell, including the membranes, wall, s-layer, capsule

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2
Q

cell wall

A

refers to the structural element defining the cell shape; the strength element preventing the cell from popping, aka peptidoglycan layer
it is ONE PART of the cell envelope

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3
Q

gram positive cells

A

has an ester linked cytoplasmic membrane with a thick peptidoglycan cell wall outside. NO OUTER MEMBRANE

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4
Q

gram negative cells

A

has an ester linked cytoplasmic membrane with a thin peptidoglycan cell wall. has an outer membrane

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5
Q

periplasm

A

the space between 2 membranes

peptidoglycan wall is within this space

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6
Q

components of the cell wall

A

also known as murein or peptidoglycan
peptide is attached to sugars. short in length so they are not proteins.
diamino acid has 2 amino groups. the amino groups are needed to make peptide bonds

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7
Q

structure of cell walls

A

glycan are long strands
peptides on the outside
peptide side chains link glycan strands together to form crosslinks
these are polymerized into one single molecule

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8
Q

transglycosylase

A

makes the glycan strand by polymerization

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9
Q

transpeptidase

A

make the peptide strands into crosslinks.

as new units are added, they’re cleaving off a terminal D and using this energy to form more chains

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10
Q

bactoprenol

A

lipid carrier for precursor transport

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11
Q

autolysins

A

means self-lysing, causing the cell to burst

cleave peptidoglycan bonds to allow expansion and insertion of new material

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12
Q

PBPs

A

penicillin binding proteins that catalyze both the glycosyltransferase and transpeptidase activities

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13
Q

degradation of bacterial cell walls

A

antibiotics, like penicillin, prevent crosslinking and cause the cell to burst
lysozymes cleave glyosidic bonds between NAG and NAM

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14
Q

prokaryotes that can live without cell walls

A

very few
mycoplasma (bacteria)
thermoplasma (archaea)
only within an isotonic environment

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15
Q

teichoic acid

A

found in gram positive cell walls
a polymer containing ribitol and sugar with phosphates attached. they are attached to the lipids and peptidoglycan
phosphates provide a negative charge to the cell surface

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16
Q

lipid A

A

found in gram negative cells

makes up the outer membrane outer leaflet

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17
Q

lipopolysaccharide (LPS)

A

attached to lipid A

18
Q

porin proteins

A

nonselective pores that let a lot of small molecules cross the outer membrane

19
Q

lipoprotein

A

attaches the outer membrane to the peptidoglycan

20
Q

periplasm

A

space between the membranes. the peptidoglycan is submerged here, as well as the site for PMF since protons accumulate here

21
Q

structure of gram negative outer membrane

A

lipid A has long fatty acid chains with sugar. frequently called endotoxin
core polysaccharide
o specific polysaccharide

22
Q

archaeal cell walls

A 
have an ether linked cytoplasmic membrane
NO peptidoglycan
NO outer membrane
SOME contain pseudomurein
beta 1,3 bonds instead of 1,4
not lysozyme sensitive
no D amino acids
not penicillin sensitive
contain N-acetyl talosaminuromic acid
23
Q

s layers

A

paracrystalline surface layer
protein or glycoprotein can self assemble. covers the entire cell surface
common in archaea functioning like a cell wall, resisting osmotic pressure

24
Q

capsule/slime layer/extracellular polysaccharide

A

used for attachment to surfaces
EPS used in biofilm formation. this holds cells together and keeps them stuck to a surface, working as millions instead of one
provide protection from phagocytosis by immune cells

25
Q

fimbriae

A 
filament made of proteins
relatively short
abundant with thousands per cell
easily fixed, stay and don't change
important in surface adherence
sticky and can bind
26
Q

pili

A 
filament made of proteins
long
fewer with 1-20 per cell
retractable, extending in and out as needed
do not rotate or swing
27
Q

functions of pili

A

adherence, retraction allows the cell to pull itself closer to things
exchange of DNA through the process of conjugation
motility

28
Q

twitching motility

A

utilizes type 4 pili
needs ability of attachment and retraction
important in pathogenesis

29
Q

flagella and swimming motility

A

rotary filaments that spin the cell forward

30
Q

polar flagella

A

only produced at the tips of the cell

31
Q

amphitrichous flagella

A

found on both poles

32
Q

lophotrichous flagella

A

only at one pole

33
Q

peritrichous flagella

A

produced all over the cell

34
Q

tumble

A

the cell rotates to a new random direction

35
Q

unidirectional flagella

A

tumble one way, stop, and spin off in another direction by random chance
like a box

36
Q

reversible flagella

A

tumble one way, stop, and go back the way they came

runs are straight lines back and forth

37
Q

motor

A

made primarily of the basal body
driving force is in the cytoplasmic membrane
a rod extends through it, forming a flexible hook at the end where the filament is attached
filament is made of protein flagellum
turning driven by PMF

38
Q

chemotaxis

A

can swim up or down gradients
is a biased random walk
can’t tell which way they’re going, but can sense concentrations of attraction
they swim in response to chemicals

39
Q

capillary assay

A

bacteria is placed in a media like buffer. a capillary with a control, attractant, or repellent is place in it as well. the bacteria will react to this presence, swimming to or from it

40
Q

phototaxis

A

bacteria swim to places containing more light, preferably with more pigment for better absorption

41
Q

aerotaxis

A

swim towards high or low oxygen concentrations

42
Q

gas vesicles

A

produced by aquatic phototrophs

little membrane sacs that accumulate gas that is trapped, giving buoyancy to keep suspension at high points in the water

Microbiology (20 decks)

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