Lecture #17: Cell membranes Flashcards
1
Q
Phospholipid
A
Polar head (hydrophilic), nonpolar tail (hydrophobic)
2
Q
Hydrophilic
A
water-LOVING
3
Q
Hydrophobic
A
water-FEARING
4
Q
Phospholipid bilayer
A
Single cell membrane
5
Q
How does steroid hormone enter phospholipid bilayer?
A
Nonpolar
- enters through simple diffusion
6
Q
Aquaporin
A
Channel for water to travel through
EX: Collecting duct
7
Q
Selective diffusion
A
- “Selected” molecule or ion has to fit the channel
- Channel has to be open
- Movement in both directions
Carrier within the channel to help a particular molecule pass through
8
Q
ATP
A
adenosine triphosphate (3 p groups)
9
Q
Desphosphorylation
A
ATP –> ADP + P + energy
- take away P group
10
Q
Phosphorylation
A
ADP + P + Energy –> ATP
- gave a P group
- doesn’t have to be ADP
11
Q
Active transport (Na+ - K+ pump)
A
- Pump opens to inside of cell
- 3 Na+ ions attach to pump
- ATP used in 2 ways
(i) energy released when ATP-> ADP
(ii) phosphate binds to pump - Changes shape of pump
- pump opens to outside - 3 Na+ released outside
- 2 K+ bind to pump from outside
- Phosphate group is released from pump
- Pump changes shape - 2 K+ released to inside
12
Q
Proton (H+) pump
A
- Energy (sunlight, breaking chemical bonds) needed to pump H+ across a membrane from an area of low concentration -> high concentration
- One possibility -> protons will diffuse back across membrane through a specialized channel - creating ATP (from ADP)
13
Q
Chloroplast
A
- stroma
- thylakoid disks
sunlight is used to pump H+ into the thylakoid disk - H+ diffuse back across membrane to produce ATP –> used for photosythesis (co2 + h2o –> glucose)
14
Q
Stroma
A
background
15
Q
Thylakoid disk
A
inner membrane
