Chapter 3 (Notes) Cell Envelope

Question 1

number of microbes

Answer 1

10^31

Question 2

microbe size range

Answer 2

0.2 micrometers to 1 millimeter

prok 0.5-5 micrometers

euk 3 micrometers - 1 mm

Question 3

microbes were first referred to as…

Answer 3

bags of chemicals

Question 4

4 important structures of a bacterial cell

Answer 4

cell wall

cell membrane

cytoplasm

nucleoid region

Question 5

cytoplasm contains _________

Answer 5

microcompartments full of ions and small molecules

Question 6

nucleoid region

Answer 6

where genome is located

Question 7

bacterial cells are _______ but flexible, and are tightly ______

Answer 7

ordered, controlled

gene regulation in response to the environment

Question 8

phospholipid bilayer components (amphipathic)

Answer 8

polar head - phosphatidate

glycero-

fatty acid chain (ester linkage)

Question 9

marine cyanobacteria may have alternative lipids like…

Answer 9

phosphatidylglycerol (PG)

SQDG

Question 10

archaeal cell memb

Answer 10

isoprene hydrophobic tails attached to glycerol by an ether

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

Question 11

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

Answer 11

uncharged, diffuse, pH

Question 12

polar molecules and charged molecules require transport through protein ________

Answer 12

transporters

Question 13

in passive transport molecules move which way

Answer 13

down [ ] gradient

Question 14

in active transport molecules move which way

Answer 14

against their [ ] gradient

requires energy

Question 15

hopanoids add ________ to membranes

Answer 15

strength

like sterols for bacteria… maintain rigidity

Question 16

biochemical makeup

Answer 16

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:

Question 17

ratios of biochemicals in a bacterial cell

Answer 17

water 70%

protein 16%

RNA 6%

phospholipids 3%

everything else .1 - 1%

Question 18

_______ are the most diverse class of molecules in the cell

Answer 18

proteins

Question 19

polyamine

Answer 19

organic molecule with many aa

stabilize neg charged DNA

regulate pH

Question 20

the cell wall is made of ________

Answer 20

peptidoglycan (murein)

beta 1,4-glycosidic bondh

Question 21

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

Answer 21

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

Question 22

function of cell memb. cell wall

Answer 22

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)

Question 23

turgor pressure of gram neg and gram pos

Answer 23

gram neg: 2-5 atm

gram pos: less than 20 atm

Question 24

what does high tensile strength do

Answer 24

allow for strength and flexibility

Question 25

how are leaflets held together

Answer 25

hydrophobic interactions

Question 26

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

Answer 26

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

Question 27

are multiple layers or peptidoglycan (murein) cross linked?

Answer 27

yes

Question 28

transpeptidase

Answer 28

bacterial enzyme that cross-links peptidoglycan chains to form layers

Question 29

beta-lactam antibiotics (penicillin)

Answer 29

irreversibly binds to and inhibits transpeptidase (acetylate serine in active site) turgor pressure then lyses cells aka. penicillin binding protein

Question 30

lysozyme

Answer 30

human body's own antibiotic found in tears breaks the beta 1,4-glycosidic bond in peptidoglycan

Question 31

beta-lactamase

Answer 31

some bacteria have this enzyme that cleaves the ring structure of beta-lactam antibiotics makes bacterium resistant to beta-lactam antibiotics evolutionary adaptation

Question 32

gram stain (differential stain)

Answer 32

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

Question 33

how to do a gram stain

Answer 33

purple crystal violet stain rinse w/ ethanol (gram pos resistant and stay purple) pink saffranin counterstain makes gram neg pink

Question 34

lipopolysaccharide (LPS)

Answer 34

found in gram neg main outward facing phospholipids acts as an endotoxin (released when lysed)

Question 35

teichoic acid

Answer 35

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

Question 36

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

Answer 36

wall, mycolic acids hard to characterize using standard techniques (eg. gram stain)

Question 37

mycoplasms are cell ____-less bacteria

Answer 37

cell wall-less bacteria membrane strengthened by sterols eg. mycoplasma pneumoniae - bacterial "walking" pneumonia

Question 38

4 ways archaeal cell walls vary

Answer 38

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

Question 39

eukaryotic microbes possess their own structures to avoid _______ shock

Answer 39

osmotic algae - cell walls of cellulose fungi - cell walls of chitin diatoms - exoskeletons of silicate paramecia - contractile vacuole to pump water out

Question 40

can ions diffuse passively through the memb?

Answer 40

no, allows for electrochemical gradient (and maintain pH)

Question 41

what small molecules can diffuse through memb

Answer 41

O2 CO2 N2 H2O

Question 42

large molecules are _______ transported

Answer 42

actively some can diffuse passively

Question 43

where is a cell envelope located

Answer 43

outside the membrane

Question 44

2 main glycerols

Answer 44

NAM n-acetylmuramic acid NAG n-acetylglucosamine

Question 45

LPS 3 parts of structure

Answer 45

o-specific chain (o-antigenic repeating subunits) core (endotoxin) lipid A ex. E. Coli O157:H7 (O antigen + H-antigen from flagella)