Chapter 5 Membranes Flashcards
Intrinsic proteins information
- TRANSMEMBRANE embedded both layers of membrane
- Amino acids with HYDROPHOBIC r groups in their external surfaces, so this can interact with the hydrophobic fatty acid core of bilayer
Intrinsic channel protein
- hydrophilic channel that allows passive movement of POLAR molecules/ ions down a concentration gradient through membranes
- held in POSITION ( by hydrophobic R group on amino acid outside and interaction with hydrophobic fatty acid outside stated previously…)
Intrinsic carrier protein
- allows BOTH passive and active transport (against concentration gradient )
- shape of protein changes for active transport
- atp
Extrinsic glycoprotein
- role is of cell adhesion ( cells joining in tissues)
- is also A receptors for chemical signal = roll in CELL SIGNALLING
- has attached carbon chain of varying length and embedded in one layer of bilayer
Cell signalling and examples (this is to do with glycoprotein receptors) what is it
- chemical binds to the receptors , releases a response from cell: either direct or chain of events in cell
Ex
1) receptors for neurotransmitters (ones thst diffuse )at nerve synapses (triggers or prevent impulse for next neurone remember)
2) Peptide hormones , like insulin glycogen (maintaining glucose concentrations)
Glycolipids
- lipids with varying carbohydrate chains
- act as cell markers = ANTIGENS, allowing immune system either recognises as self or non self (belonging to other organism)
- also form hydrogen bonds with water molecules to stabilise membranes
Extrinsic proteins information
- hydrophilic r groups on their outer layer so they can interact with polar heads of phospholipids (or with intrinsic proteins )
- can move layers
Cholesterol
Structure
Function how does it regulate fluidity
How does it give stability?
=lipid that regulates fluidity of membranes , gives stability
- cholesterol has hydrophilic OH- group on ONE END so interact with heads and hydrophobic end of carbon ring
THIS IS WHAT IT BINDS WITH the fatty acid tails
2) in low temps makes them fluids by not allowing phospholipids from coming too close and Crystal aight to become a solid
- in high temps stops phospholipids from becoming too fluid aswell, interactions between head and tail PULL THE PHOSPHOLIPIDS TOGETHER
- causes phospholipids to pack closely together, making them MORE STABLE without rigid.
What proteins need to be for chemical reactions to happen
What example - you got this wrong in test
In specific places
- for example electron carriers and protein enzyme ATP synthase has to be on inner membrane mitochondria, CRISTAE and in correct positions so respiration Can take place.
- remember Cristae contain all enzymes needed for light dependent reactions 😪
What is compartmentalisation?
Why is it important (3)
The formation of separate membrane bound areas in a cells
2) 1: incompatible reactions occur within the cell , compartmentalisation isolates them allowing them to happen
2: it allows different conditions to be set for Esch reaction, like gradients etc to get best reaction
3: protects cell components from harmful Hydrolytic enzymes from lysozyme potentially
What is the use of a plasma membrane?
- separates cell contents fro, the outside (barrier)
- controls passage in and out of cells
- allows cells to communicate ,
- recognition of other cells is possible here
What is the function of organelle bound membranes ?
- also helps isolate dna
- acts as an intracellular transport system
- site of chemical reactions, form vesicles for transport etc
Describe the arrangement of the phospholipid bilayer?
Phospholipids contain a polar, and thus hydrophilic phosphate head and two hydrophobic fatty acid tails .
-Thus two layers of phospholipids form such that the polar hydrophilic phosphate heads orientate themselves to be on the outside whilst the fatty acid hydrophobic tails are SANDWICHED on the inside.
- This allows the bilayer to be able to interact with both the interior and exterior aqueous environment
- whilst still protecting the hydrophobic fatty acid core.
What makes the membrane known as a fluid mosaic model?
Fluid = phospholipids and proteins are free to move throughout the layer relative to Esch other Mosaic = because the various different proteins embedded in the protein vary in shape and size, forming a mosaic like pattern in the membrane (just like a mosaic).
How do the phospholipids move!
Why can they move around!
Side to side like 10^7 times per second
- flip flopping once per month
2) they ade held together by weak hydrophobic interactions which allows them to be fluid
