lecture 1

Question 1

what are multicellular organisms composed of

Answer 1

many different cell types

Question 2

animal cell specific

Answer 2

extracellular matrix: specialized material outside of the cell

lysosome: degradation of cellular components that are no longer needed

Question 3

plant cell specific

Answer 3

cell wall: cell shape and protection against mechanical stress

vacuoles: degradation and storage

chloroplasts: site of photosynthesis

Question 4

membrane bilayers

Answer 4

two layers or leaflets of lipid molecules

Question 5

what is a lipid

Answer 5

hydrophilic head (polar group)
hydrophobic tail
contains differentiating group, phosphate, and glycerol

Question 6

tails of phospholipids

Answer 6

saturated = straight tail, single bonds, full of hydrogen
unsaturated = double bonds, kinked

Question 7

membrane bilayers

Answer 7

when in an aqueous environment they spontaneously self-associate into a bilayer
polar head interacts with water so face outwards

Question 8

fluidity of membranes

Answer 8

so a membrane can be deformed without damage being caused
it is carefully regulated as it is important for function, transport, enzyme activity, signalling

Question 9

factors that affect fluidity

Answer 9

temperature (low=less fluid)
saturation of phospholipids (double bonds=more fluid)
length of tails (shorter=more fluid)
addition of cholesterol (flips how it acts temperature wise)

Question 10

scramblase

Answer 10

random flip-flop of random phospholipids

Question 11

flippase

Answer 11

rapid flip-flop pf specific phospholipids in cytosolic leaflet

Question 12

membrane proteins

Answer 12

have specific funtion
are associated with lipid bilayer

Question 13

integral membrane proteins

Answer 13

they are directly attatched to the bilayer, either inserted or attatched to a lipid
detergent for extraction

Question 14

peripheral membrane proteins

Answer 14

can be on either face of the membrane, is bound to other proteins/lipids, bound by non-covalent interactions
gentle extraction methods

Question 15

transmembrane proteins

Answer 15

they are amphipathic, hydrophilic domains outside cell, hydrophobic membrane spanning domails
can be single/multiple alpha helix or beta barrel

Question 16

transmembrane protein functions

Answer 16

transporters and channels, anchors, receptors, enzymes

Question 17

how are transmembranes identified

Answer 17

x-ray crystallography, hydrophobicity plot

Question 18

monolayer-associated membrane proteins

Answer 18

they are anchored on cytosolic face by amphipathic alpha helix

Question 19

lipid linked membrane proteins

Answer 19

has GPI anchor (synthesizes in ER lumen and ends up on cell surface) or with another lipid anchor (cytosolic enzymes add the anchor, protein is directed to the cytosolic face)

Question 20

lateral diffusion of membrane proteins

Answer 20

only exists within the leaflet
FRAP
can be restricted

Question 21

FRAP

Answer 21

labelled tith fluorescent antibody, photobleached with lazor, observed how long it take for unbleached proteins to move around