CP 4 Cell Membranes and Signalling Flashcards
describe the fluid mosaic model
○ Plasma memb is fluid mosaic of lipids and proteins
○ Fluid lipid bilayer, proteins float freely
What are peripheral proteins
○ Only interact with polar head groups of bilayer
○ Don’t go all the way thru like the other proteins
TF lipids are not good insulators
F Lipids r very good insulators
What is the Protein-Lipid composition in: nerve insulation
More lipids less proteins
What is the Protein-Lipid composition in: The plasma membrane
pretty much 1;1
What is the Protein-Lipid composition in: Electron transport
More proteins less lipids
TF phosplolipids are amphipathic (hydrophilic end and hydrophobic end)
T
What is the phospholipid structure
1 phosphorus and 3 fatty acids
TF the bilayer structure depends on the lipid concentration
T
TF the membrane monolayers have different composition
T,
External: Glycolipids, carbs, receptor proteins
Internal: Cytoskeleton
what happens to a cell if the cell fluidity is low
membrane turns gel-like, could die
What happens to a cell if the membrane fluidity is too high
Allows potentially dangerous molecules to get thru
TF unsaturated hydrocarbon tails are Viscous
F, they r fluid
TF saturated hydrocarbon tails r fluid
F, they r viscous
TF the longer the fatty acid tail the more viscous the membrane
T
What is the name of the enzyme that takes H+ from unsaturated fatty acid to make a double C bond
Desaturase
What is desaturase used for
to increase membrane fluidity
A higher temperature ______ membrane fluidity
increases
What are the 3 Major factors to membrane fluidity
1) structure of phospholipid tails
2) Temperature
3) Cholesterol levels
How is cholesterol arranged
- Arranged the same way as phospholipids
○ Head outwards and tail inside- Hydrophilic head and hydrophobic tail
What is a function of cholesterol
Act as a buffer
In higher temps, cholesterol will ______ fluidity and ______ movement of lipids
Reduce
Restrain
In lower temps, cholesterol will ______ fluidity and ______ lipids from gelling
Increase
Prevent
what is the difference between integral anf peripheral membrane protiens
Integral membrane proteins
- Contains hydrophobic domains that cross the bilayer
- Transmembrane domain
○ Has stretches of non-polar amino acids
Peripheral proteins
- Sits on the surface and form noncovalent bonds with lipids and membrane proteins
- Has no interaction with hydrophobic core
what r 4 diff types of proteins we see in the membrane
transporters
enzymes
signal transduction
attachment
what do transporter protiens do
Provides channel for movement of molecules
how does an enzyme work in the membrane
Substrate binds to active site on enzyme
What are the steps to Signal Transduction
Reception –> Transduction –> Response
What is the function of attachment protiens
Cytoskeleton and cell to cell recognition
What are the different types of transport
Active
Passive
What are the characteristics of passive transport
- Requires no energy
- Moves from high to low concentration
what is facilitated diffusion
- type of passive transport
○ Large, uncharged polar molecs need carrier proteins to get thru
○ Channel proteins are corridors in memb. To allow a specific molec to pass (some gated or volt)
What are the characteristics of Active Transport
- Dragged across concent. gradient so it req ATP
○ Moves Na out and K in (both against their concent gradient)
○ Proton pump, Keeps pH low, Generates membrane potential
What is secondary active transport
○ Use ion gradients created by primary active transport
○ Coupled with primary pump
What is Cotransport
2 solutes moving together
what is antiport
Transported solute moves in the direction opposite from the gradient driving ion
why is active transport needed
- Uptake of essential nutrients at lower extracellular concentration
- Removal of secretory waste at higher extracellular concent.
- Maintain constant intercellular concentrations of Na, H, K, Ca
- Maintain membrane potential (voltage difference across plasma memb.)
what is osmosis
- Type of passive diffusion that applies to water molecules
- Moves from high to low concent across a selectively permeable membrane
what is the plant versions of:
isotonic
hypotonic
hypertonic
Flaccid
Plasmolysis
Turgid
what is Tonicity
he cells ability to gain and lose water
