Cell Physiology Flashcards
What molecules make up the plasma membrane?
- Phospholipid bilayer
- Steroids (cholesterol)
- Glycolipids
- Membrane proteins (intrinsic, extrinsic, and glycoproteins)
What is the basic structure of the plasma membrane?
phospholipid bilayer with differing ratios of proteins and steroids dispersed throughout
Describe
Phospholipid
a lipid containing a phosphate group in its molecule; polar head group with non-polar tails
Describe
Plasma Membrane Steroids
In particular cholesterol; amphiphatic molecules that maintain proper membrane fluidity
There is one molecule of cholesterol for each molecule of phospholipid
How is the structure of the phospholipid bilayer formed?
Spontaneously; the polar heads face the aqueous enviornment while the nonpolar tails form the hydrophobic core
Describe
Glycolipids
Lipids with CHO chain attached that are found on the outer leaflet of plasma membrane
* Amphipathic
* Form glycocalyx
Describe
Integral (intrinsic) Proteins
- Amphipathic – inserted into phospholipid bilayer of plasma/cell membrane and partially span membrane or are transmembrane proteins (completely cross phospholipid bilayer of membrane)
- Comprise the majority (70%) of all proteins
- Examples: transporters or channels
Describe
Peripheral (extrinsic) Proteins
- a class of membrane proteins that attach to the lipid bilayer, acting on the lipid-water interface
- NOT amphipathic
- on the inner/outer surface of membrane
Describe
Glycoproteins
- Protein with attached carbohydrates
- Extracellular surface of plasma membrane (forms glycocalyx)
What are the three types of cell junctions?
- Desmosomes
- Tight Junctions
- Gap Junctions
What are the components of desmosomes?
- Adhering junctions
- Plaques
- Cadherins
- Intermediate filaments
Describe
Adhering junctions
- Anchor cells together in tissues subject to considerable stretching
- Structural integrity to tissues
Describe
Plaques
Component of adhering junctions
* Cytoplasmic
* Anchoring points for cadherins
Describe
Cadherins
Component of adhering junctions
* Links cells together
Describe
Intermediate filaments
Component of adhering junctions
* Anchor cytoplasmic surface of desmosomes to cell components
* Structural support