U2-L3 Plasma membrane structure and transport Flashcards
(18 cards)
Plasma membrane function: - 3
- Regulates transport between the cell and the outside
- Mediates interactions between cells
- Separates and protects your components from the external environment
Chemical composition of the plasma membrane: - 3
- All plasma membranes have the same components
- They appear in different proportions depending on the membranes
- Asymmetric distribution
what is the plasma membrane made of - 2
- a fluid mosaic formed by a lipid bilayer in which proteins are embedded in it
- both proteins and lipids can move laterally
characteristics of protein in cytoplasm - 2
- Amphipathic molecules
- Responsible for the concentration of ions between two compartments
2 classification of proteins in cytoplasm
- Integral proteins, usually transmembrane ports
- Peripheral proteins
function of proteins in cytoplasm - 6
- Transport of molecules
- Part of cell to cell binding structures to form tissues
- Connection of the membrane to the cytoskeleton
- Receptors
- Cell-cell recognition and message transmission
- Reactions catalysts
characteristics of carbs:
- Protein bound → glycoproteins
- Lipid-bound → glycolipids
- Asymmetric distribution: always on the outside surface of the membrane
- They form the cellular glycocalyx
function of carbs - 2
- Cellular recognition
- Immune properties (blood types ABO)
characteristics of lipids:
- They are part of all biological membranes
- They appear in different proportions depending on the membranes
- They are amphipathic molecules (hydrophilic + phobic)
types of lipids
- Phospholipids –> Two tails of fatty acids and a head
- Cholesterol
- Glycolipids
what happens to the lipid bilayer in an aqueous environment
In an aqueous environment, the lipid bilayer spontaneously closes in on itself to form enclosed compartments
Transport across the plasma membrane:
Why is membrane transport necessary? - 3
- Cellular nutrition (introduce glucose, fatty acids..)
- Excretion (removing waste products)
- Cell communication (pouring molecules that other cells receive
2 ways to transport small molecules across plasma membrane:
- passive transport
- active transport
transport of small molecules: passive transport
* energy expenditure needed or no
* atp or no atp needed
* types of diffusion - 2
* types - 2
* against or with gradient
- No energy expenditure = no ATP needed
types of diffusion:
1. simple diffusion
* no transport protein needed
* it is going with the gradient
2. facilitated diffusion
types:
- channel mediated
- trasnport mediated
* need a protein to pass through
* goes against its gradient
types:
- trasnporters
- channels
transport of small molecules: active transport
- energy expenditure needed or no
- atp or no atp needed
- types - 2
- against or with gradient
types
1. primary
- a protein pump uses ATP to transport molecules against gradient
- secondary
* to move against its gradient a molecule takes advantage of another molecule moving down its gradient
what do transporters do
- There is interaction between the molecule and the transporter
- Ex: incorporation of glucose into the cell
types of channels
