membrane structure

what are the 2 components of the basic structure of a lipid

1. glycerol- hydrophilic head of lipid

2. fatty acid - hydrophobic tail of lipid

whats the chemical structure of the glycerol in a lipid

3 carbon chain backbone with 3 OH groups (make it hydrophilic) where the fatty acids attach

whats the chemical structure of the fatty acid tail of the lipid

lots of CH’s making it hydrophilic. and an OH that attaches to the OH of a glycerol through dehydration synthesis (lose H2O)

whats it called when we attach 3 fatty acid chains to the glycerol

triacylglycerols

whats the type of lipid we see in cell membranes

phospholipids- that have only 2 fatty acid chains.

whats the structure of the phospholipid

1. only 2 fatty acid tails- non polar

2. glycerol+ phosphate+ polar molecule in head - polar

how do kinks form in the fatty acid chains in the lipids, when we have a lot of kinks what does that do to the cell membrane

a double bond in the chain, that’s caused by it being unsaturated

• lots of kinks makes It more fluid, bc more double bonds don’t allow fatty acid tails to stack on top of one another tightly.

in the membranes lipid bilayer what direction to the phospholipids face

the heads of the lipids are polar so they will always face the outside while the tails are inside the membrane. with 2 layers so no water gets in middle.

whats the term that describes a molecule that has hydrophobic and hydrophilic parts to it

amphipathic

what 2 structures can form if the lipid only has 1 fatty acid tail

1. surface film, - float at top of water

2. micelle - cannot from phospholipids bc no room for other layer (to form bilayer)

fats be saturated or unsaturated, how do you tell the diff

unsaturated- has kinks in chain with double bonds- making it more fluid

saturated- all single bonds so its straight and stackable,- making it less fluid

which fatty acid would be solid at room temp

saturated- bc its straight and stackable/compact so it becomes solid. ex. butter

unsaturated- has kinks making it loose so it’ll be liquid. ex. oil

whats the 3 types of fatty acids

1. saturated fat

2. unsaturated fat

3. trans fat- scientifically made.

what happens when the kinked fatty acid (liquid) is hydrogenated (by scientists )

it turns into solid, bc the “cis double bond” turns into trans double bond= straight fatty acid chains.

whats the lipid bilayer officialy called

fluid mosaic bilayer

Membrane composition: whats the structure of cholesterol in cell membrane

• lil polar head

• ring structure attached to head

• then its non polar tail

It goes inbwtween the phospholipids and helps straighten the structure by going in-between the kinks of the tails. making the membrane less fluid.

Membrane compositon: sugars can help differentiate cells

glycoprotein- when sugar is attached to protein

glycolipid- when sugar is attached to lipid

Membrane Movement: whats the term for when phospholipids are moving back and forth

lateral diffusion

• phospholipids rarely flip flop from one monolayer to the other

when new phospholipids are made from smooth er, where do they attach in membrane bilayer

to the “cytosolic half” (monolayer touching cytoplasm)

as we add new phospholipids to one monolayer, it becomes uneven compared to the other monolayer, what enzyme solves this

Scrambles enzyme- it transfers random phospholipids from one monolayer to the other to balance it out

in some cells they want a certain type of phospholipid on each monolayer. so what enzyme causes this

flippase- as chunk of membrane comes it flips certain lipids to match

whats the n- termini and c- termini

n-termini: outside monolayer

c-termini- inside monolayer

what are integral membrane proteins 3 types

proteins imbedded in membrane

1. transmembrane protein

2. monolayer associated

3. lipid linked

what are transmembrane proteins

proteins that go all the way through the membrane

monolayer associated

proteins that only go through one monolayer but not both

lipid linked

proteins chemically bonded to certain lipids in membrane

whats peripheral membrane proteins

proteins not imbedded in membrane but are associated

If 2 cells fuse what would it looks like

they would be Half n half at first but then would mix bc the cell is fluid.

how would temp affect cell fluidity

cold= less movement and fluidity- stiff

warm=more movement and fluidity

what can restrict cell movement

tight junctions, they hold together cell membrane proteins