Topic 2: Cell Physiology 1 - The Cell Membrane Flashcards
What are the 3 structures found within the cell membrane?
- Phospholipid bilayer
- Membrane Proteins
- Membrane carbohydrates
What is the phospholipid bilayer?
- continuous layer around the cell
What is the function of the phospholipid bilayer?
barrier to water soluble substances
What is the phospholipid bilayer permeable to? (2)
- permeable to small molecules (CO2 and O2)
- lipid soluble molecules
What are the 5 types of membrane proteins?
- Transport proteins
- Receptor proteins
- enzymes
- Joining proteins
- Identifying proteins
What are 2 types of transport proteins?
- channel
- carrier
What do channel proteins form in the membrane?
- form pore in membrane
What is the function of a channel protein?
- selectively permit channel-mediated facilitated diffusion of water and specific ions
Channel proteins can either be ___ or non-___
gated, non-gated
What is a gated channel protein?
- can open or close when signaled
What is a non-gated channel protein? (2)
- leakage channels
- always open
What is the function of carrier proteins?
- bind solute and carry it across membrane
What do carrier proteins allow for?
- allow protein carrier-mediated facilitated transport OR active transport
What is a good example of a carrier protein?
glucose transport
- depends on where in the body (depends on CG)
What is the function of receptor proteins?
- can bind specific extracellular molecules (ligands)
ex. hormones, neurotransmitters
Glucose uptake is an example of a receptor protein. What occurs here? (4)
- by skeletal muscle cells or adipose tissue
1. insulin binds to receptor on skeletal muscle or adipose tissue
2. Triggers movement of more glucose transporters to cell membrane
3. Increased glucose movement from blood into cells
What is the function of enzymes?
- Control chemical reactions on outer or inner surface
ex. acetylcholinesterase
ex. Na/K - ATPase where all cells have this
What is the function of joining proteins?
- anchor cell membrane to cytoskeleton or an adjacent cell
What are 2 types of joining proteins?
- junctional proteins
- extracellular fibers (usually glycoproteins)
What do junctional proteins between cells form? (3)
- desmosomes
- tight junctions
- gap junctions
What is an example of an identifying protein?
- Major Histocompatibility Complex (MHC)
Where are MHC proteins found?
- On surface of all cells except RBC
What is the function of MHC proteins?
identify cell as “self” (part of the body)
- not foreign
What are 2 membrane carbohydrates?
- glycoproteins and glycolipids
note that it is attached to lipid on phospholipid bilayer
What is the function of membrane carbohydrates? (2)
- differs for every cell type
- allows cell to recognize type
ex. sperm recognizes egg
