Week 3 Flashcards
bacterial cell envelope is anything ______
from the plasma membrane out
parts of gram + bacteria cell envelope (inner to out)
-periplasm (gel-like cytoplasm outside pm)
-thick peptidoglycan layer
parts of gram - bacteria cell envelope (inner to out)
-periplasm (gel-like cytoplasm outside pm)
-thin peptidoglycan layer
-periplasm (gel-like cytoplasm outside pm)
-outer membrane (only in gram -)
PM are mostly ______
phospholipids and carbohydrates with proteins imbedded within
functions of cytoplasmic membrane
1) permeability barrier: prevents leakage, transport of nutrients in and wastes out
2) protein anchor: proteins participate in transport etc.
3) energy conservation: charge differential across membrane
parts of PM
fatty acid tail chains –> glycerol –> phosphate head group –> sidechain
glycerol is connected to lipid tails in PM by ____ in bacteria and eurkarya but not archaea (____)
-ester linkage
-ether linkage
saturated fatty acids are ____
unsaturated fatty acids are _____
-straight, inflexible
-kinky, mobile
types of phospholipids most common in e-coli
-Phosphatidylethanolamine
-Phosphatidylserine
phospholipid + side chain
a) Phosphatidic acid
b) Phosphatidylethanolamine
c) Phosphatidylserine
d) Phosphatidylcholine
e) Phosphatidylglycerol
f) Cardiolipin
a) X=H
b) X=CH2CH2NH3
c) X=CH2CH2(NH3)COOH
d) X=CH2CH2N(CH3)3
e) X=CH2CH(OH)CH2OH
f) X=Phosphatidylglycerol
lipid acyl chains affects _____
membrane fluidity
PM with only saturated lipids is needed for _____
bacteria that lives in high temp
PM with mixed saturated/unsaturated lipids is needed for _____
bacteria that lives in low temp
____ , an activated carrier molecule, is also part of PM and consists of _____.
-undecaprenyl pyrophosphate
-55C in isoprene units and 2 PO4
integral membrane proteins are ____
imbedded in the membrane
types of integral membrane proteins
1) monotopic alpha helix - cross PM once
2) polytopic alpha helices - cross PM more than once
3) polytopic beta barrel - cross PM more than once
peripheral membrane proteins are ______
associated with membrane on either side but not imbedded
types of peripheral membrane proteins
1) alpha helix (part of protein associates with membrane)
2) loops associated with membrane
3) acylated (fatty acid attached imbedded in membrane)
4) ionic (charged interactions with hydrophilic head groups)
diffusion (def., energy requirement, permitted/not permitted to pass)
- Free movement of molecules along a concentration gradient
- Does not require energy (passive)
- Permitted: Small hydrophobic molecules, Water, O2,CO2
- Not permitted: Charged molecules (ions), large hydrophilic molecules (sugars, NA. proteins, etc.)
osmosis (def.)
Movement of water along a concentration gradient
osmosis can do what?
Can exert a physical force on the membrane
hypertonic solution (def.) + effect on cell
-[H2O] outside cell < [H2O] inside cell
-H2O leaves cell & cell dehydrates
isotonic solution (def.) + effect on cell
-[H2O] outside cell = [H2O] inside cell
-no net movement of water
isotonic solution of bacteria is not ____
saline like for animal cells
hypotonic solution (def.) + effect on cell
-[H2O] outside cell > [H2O] inside cell
-animal: H2O enters cell & cell burst no net movement of water
-bacteria: peptidoglycan and S-layers prevent cell from bursting
facilitated diffusion (def., energy requirement, permitted/not permitted to pass)
- Movement of molecules along a concentration
gradient - requires a protein carrier that is selective for its substarte (size-dependent) - Does not require energy (passive)
- Ions, sugars, amino acids can pass
In facilitated diffusion, movement rate is determined by ____
the number of transporters & transporter affinity for solute & a bit of [solute]
in simple diffusion, movement rate is ____
directly proportional to [solute] - linear
types of transporters
-uniport
-symport
-antiport
uniport (def.)
protein transporter that moves one molecule across membrane, usually facilitated diffusion
symport (def.)
protein transporter that moves two molecules across membrane in same direction (can use energy from proton motive force)
antiport (def.)
protein transporter that moves two molecules across membrane in opposite direction (can use energy from proton motive force)
proton motive force (PMF) (def.)
- Higher concentration of protons outside the cell
- Protons want to go inside cell along concentration gradient
- Proton movement contains energy
PMF can be used to transport _______
molecules against a concentration gradient
