Cell Membrane Flashcards
What is the cell membrane?
The cell membrane controls what enters and exists the cell, it is a semi-permeable subject made of a phospholipid bylayer embedded with proteins.
Phospholipid bilayer
- 2 layers
- made of a phosphate head which is polar and hydrophilic
- made of a fatty acid tail which is non-polar and hydrophobic
- Includes channel, carrier, recognition and receptor proteins
Fluid mosaic model
Fluid - flowing freely
mosaic pattern which the embedded proteins make
Intracellular
Inside the cell
Extracellular
Outside the cell
Channel proteins function:
Passive diffusion
Carrier proteins function:
facilitated diffusion
Active Transport
Move substances from an area of low to high concentration
- carrier protein
Passive transport
Moves substances from an area of high concentration to an area of low concentration
- Channel protein
Osmosis
- Movement of water
- Occurs through aquaporins (channel proteins)
Exocytosis
The movement of molecules out of the cell in vesicles that release their contents to the outside of the cell
Endocytosis
a mode of active transport where cell engulf extracellular molecules
- Phagocytosis: solids enter the cell
- Pinocytosis: liquids enter the cell
What factors affect exchange:
- Physical properties
- Electro-chemical properties
- Concentration gradient
- Surface area to Volume ratio
Isotonic:
Equal amount of solute on both sides
Hypertonic:
Less solute on the inside compared to the outside
- cell with shrink
Hypotonic:
Less solute on the outside compared to the inside
- cell will increase or burst
Factors that affect the rate that material can move over a membrane
- Surface area to volume
- concentration
- Size
- charge
- Temperature
Active modes of transport
Active transport endocytosis exocytosis pinocytosis Phagocytosis
Phagocytosis
The process by which a cell surrounds and takes in solid particles
Pinocytosis
The process by which cells enfold, and take in, drops of liquid
Exocystosis
the process by which the contents of the vesicles of the cells are pushed out through the cell membrane
Is the head of the bilayer hydrophilic or hydrophobic.
Tail = hydrophobic Head = hydrophilic
