Lecture #17: Cell membranes Flashcards
Phospholipid
Polar head (hydrophilic), nonpolar tail (hydrophobic)
Hydrophilic
water-LOVING
Hydrophobic
water-FEARING
Phospholipid bilayer
Single cell membrane
How does steroid hormone enter phospholipid bilayer?
Nonpolar
- enters through simple diffusion
Aquaporin
Channel for water to travel through
EX: Collecting duct
Selective diffusion
- “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
ATP
adenosine triphosphate (3 p groups)
Desphosphorylation
ATP –> ADP + P + energy
- take away P group
Phosphorylation
ADP + P + Energy –> ATP
- gave a P group
- doesn’t have to be ADP
Active transport (Na+ - K+ pump)
- 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
Proton (H+) pump
- 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)
Chloroplast
- 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)
Stroma
background
Thylakoid disk
inner membrane
Co-transport
- Link a pump with a diffusion channel
- build up H+ or Na+ - and diffuse back cotransporting another molecule
Which of the following are found in bacteria (prokaryotes)?
- cell membrane
- plasmids
- chromosomes
- lysosomes
- rough ER
Which of the following have a double membrane, a single membrane, or no membrane?
- Nuclear envelope= double membrane
- Chloroplasts = double membrane
- Vesicle = single membrane
- Centriole (part of centrosome) = No membrane
- Smooth ER = single membrane
- Lysosome = single membrane
- Ribosome = no membrane
- Golgi complex = Single membrane
- Basal body = no membrane
- Mitochondria = double membrane
