Membrane Transport - BIO 102 CONTENT Flashcards
1
Q
Transport across Membranes
A
- Cells are required to maintain a steady internal environment called homeostasis, or maintenance of a dynamic equilibrium
- In order for cells to do this food, water and other substances must be able to cross the phospholipid bilayer
2
Q
What are the two major forms of membrane transport?
A
- Passive Transport (no energy)
- Active Transport (Requires energy)
3
Q
Passive Transport
A
- No chemical energy required
- Movement of substances across membranes down its electrochemical gradient
4
Q
Simple Diffusion
A
- Movement of substances from an area of high concentration to an area of low concentration
- Called movement “down a concentration gradient”
- Diffusion is only useful over short distances
5
Q
Electrochemical gradient
A
Diffusion gradient of an ion influenced by ion concentration and membrane potential
6
Q
In living organisms what molecules use simple diffusion?
A
- Small, uncharged, non-polar molecules
- Like oxygen and carbon dioxide
7
Q
Facilitated Diffusion
A
- Diffusion across a membrane at a faster rate
- This is due to the assistance from transport proteins
8
Q
What are the two types of transport proteins involved in facilitated diffusion?
A
- Channel Proteins
- Carrier Proteins
9
Q
Channel Proteins
A
- Have a tunnel-like shape that allows charged molecules and ions to pass through
- Hydrophilic channel
- Can be gated channels
10
Q
Carrier Proteins
A
- Transport uncharged molecules
- Bind to molecules and transport them across a membrane
- Alter their shape in the process
11
Q
Osmosis
A
- The diffusion of water, across a membrane
12
Q
Osmotic Pressure
A
- Pressure created by water molecules as they try to reach equilibrium across a membrane
13
Q
Turgor Pressure
A
- Outward pressure on the cell wall exerted by water in the vacuole of a plant cell
14
Q
Plasmolysis
A
- Shrinkage of the cell membrane away from the cell wall, due to the loss of water
- Causes plants to wilt
