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Microbiology > Chapter 3 (Notes) Cell Envelope > Flashcards

Chapter 3 (Notes) Cell Envelope Flashcards

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Biology 101 flashcards
1
Q

number of microbes

A

10^31

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2
Q

microbe size range

A

0.2 micrometers to 1 millimeter

prok 0.5-5 micrometers

euk 3 micrometers - 1 mm

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3
Q

microbes were first referred to as…

A

bags of chemicals

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4
Q

4 important structures of a bacterial cell

A

cell wall

cell membrane

cytoplasm

nucleoid region

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5
Q

cytoplasm contains _________

A

microcompartments full of ions and small molecules

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6
Q

nucleoid region

A

where genome is located

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7
Q

bacterial cells are _______ but flexible, and are tightly ______

A

ordered, controlled

gene regulation in response to the environment

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8
Q

phospholipid bilayer components (amphipathic)

A

polar head - phosphatidate

glycero-

fatty acid chain (ester linkage)

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9
Q

marine cyanobacteria may have alternative lipids like…

A

phosphatidylglycerol (PG)

SQDG

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10
Q

archaeal cell memb

A

isoprene hydrophobic tails attached to glycerol by an ether

sometimes a lipid monolayer, not bilayer (more stable at higher T)

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11
Q

weak acids and weak bases exist partly in an ________ form that can _______ across the membrane and change the __ of the cell

A

uncharged, diffuse, pH

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12
Q

polar molecules and charged molecules require transport through protein ________

A

transporters

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13
Q

in passive transport molecules move which way

A

down [ ] gradient

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14
Q

in active transport molecules move which way

A

against their [ ] gradient

requires energy

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15
Q

hopanoids add ________ to membranes

A

strength

like sterols for bacteria… maintain rigidity

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16
Q

biochemical makeup

A

70% water (typical of all cellular life)

essential ions: Na, K, Cl, H

macromolecules: protein, nucleic acid carbohydrate, lipid
metabolites: things the cell is making (intermediate or final product)

polyamines:

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17
Q

ratios of biochemicals in a bacterial cell

A

water 70%

protein 16%

RNA 6%

phospholipids 3%

everything else .1 - 1%

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18
Q

_______ are the most diverse class of molecules in the cell

A

proteins

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19
Q

polyamine

A

organic molecule with many aa

stabilize neg charged DNA

regulate pH

20
Q

the cell wall is made of ________

A

peptidoglycan (murein)

beta 1,4-glycosidic bondh

21
Q

in peptidoglycan, the ______ chains of ____ and ____ are crosslinked to each other by short ______

A

glycan (sugar), NAM (n-acetylmuramic acid), NAG (n-acetylglucosamine), peptides

22
Q

function of cell memb. cell wall

A

barrier btw inside and outside

selectivity - passive/active transport

maintain turgor pressure

high tensile strength and elasticity

attachment point

energy storage via electrochemical gradient (proton motive force)

23
Q

turgor pressure of gram neg and gram pos

A

gram neg: 2-5 atm

gram pos: less than 20 atm

24
Q

what does high tensile strength do

A

allow for strength and flexibility

25
Q

how are leaflets held together

A

hydrophobic interactions

26
Q

is the molecule makeup of cross-bridges in peptidoglycan species specific?

A

yes, results in different strengths and rigidities of the cell wall

27
Q

are multiple layers or peptidoglycan (murein) cross linked?

A

yes

28
Q

transpeptidase

A

bacterial enzyme that cross-links peptidoglycan chains to form layers

29
Q

beta-lactam antibiotics (penicillin)

A

irreversibly binds to and inhibits transpeptidase (acetylate serine in active site)

turgor pressure then lyses cells

aka. penicillin binding protein

30
Q

lysozyme

A

human body’s own antibiotic

found in tears

breaks the beta 1,4-glycosidic bond in peptidoglycan

31
Q

beta-lactamase

A

some bacteria have this enzyme that cleaves the ring structure of beta-lactam antibiotics

makes bacterium resistant to beta-lactam antibiotics

evolutionary adaptation

32
Q

gram stain (differential stain)

A

distinguish btw gram pos and gram neg b/c of different cell wall structures

gram neg: thin cell wall with 1-2 layers or peptidoglycan enclosed by outer memb with LPS

gram pos: thick cell wall with 3-20 layers of peptidoglycan w/ teichoic acids

33
Q

how to do a gram stain

A

purple crystal violet stain

rinse w/ ethanol (gram pos resistant and stay purple)

pink saffranin counterstain makes gram neg pink

34
Q

lipopolysaccharide (LPS)

A

found in gram neg

main outward facing phospholipids

acts as an endotoxin (released when lysed)

35
Q

teichoic acid

A

found in gram pos

net negative charge allow binding of cations and attachments to pos charged surfaces

attachments for bacteriophage

varying length depending on species

36
Q

acid-fast bacteria have a different cell ____ that contains ______ acids

A

wall, mycolic acids

hard to characterize using standard techniques (eg. gram stain)

37
Q

mycoplasms are cell ____-less bacteria

A

cell wall-less bacteria

membrane strengthened by sterols

eg. mycoplasma pneumoniae - bacterial “walking” pneumonia

38
Q

4 ways archaeal cell walls vary

A

some dont have cell walls; have cell memb. made of lipoglycan

some have simple s-layers made of glycoproteins

some have rigid cell walls of polysaccharide

some have pseudopeptidoglycan with L aas and NAG/NAT backbone with beta 1,3 linkages

39
Q

eukaryotic microbes possess their own structures to avoid _______ shock

A

osmotic

algae - cell walls of cellulose

fungi - cell walls of chitin

diatoms - exoskeletons of silicate

paramecia - contractile vacuole to pump water out

40
Q

can ions diffuse passively through the memb?

A

no, allows for electrochemical gradient (and maintain pH)

41
Q

what small molecules can diffuse through memb

A

O2

CO2

N2

H2O

42
Q

large molecules are _______ transported

A

actively

some can diffuse passively

43
Q

where is a cell envelope located

A

outside the membrane

44
Q

2 main glycerols

A

NAM n-acetylmuramic acid

NAG n-acetylglucosamine

45
Q

LPS 3 parts of structure

A

o-specific chain (o-antigenic repeating subunits)

core (endotoxin)

lipid A

ex. E. Coli O157:H7 (O antigen + H-antigen from flagella)

Microbiology (19 decks)

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