Cell membrane

Question 1

Parts that make up the cell membrane

Answer 1

• lipids
• proteins
• carbohydrates

Question 2

Two parts of phospholipids and their functions

Answer 2

Phosphate head: Hydrophilic, polar, form hydrogen bonds with water

Fatty acid tail: Hydrophobic, nonpolar, no hydrogen bonds

Question 3

amphipathic molecule

Answer 3

a molecule with both hydrophilic and hydrophobic regions

Question 4

Draw a lipid with labeled regions

Question 5

Three shapes of lipids

Answer 5

Micelle: bulky head and one fatty tails
Bilayer: small head two fatty tails
Liposomes: Spherical form of lipids

Question 6

What conditions affect the lipid bilayer?

Answer 6

1. concentration of lipids
2. The PH of the cell
3. Temperature

Question 7

How does Van der Waals forces effect lipid mobility?

Answer 7

The more van der Waals forces the less mobile the lipid becomes

Question 8

How does saturation effect lipids mobility

Answer 8

1. The more saturated means more van der Waals forces between hydrogen bonds, so less mobility
2. The more saturated means longer fatty acid chains which cause less mobility

Question 9

Parts of cholesterol

Answer 9

1. The hydroxyl group: Hydrophilic
2. 4 connected carbon rings with a hydrocarbon chain

Question 10

How does Cholesterol affect membrane fluidity?

Answer 10

At normal temperature cholesterol decreases fluidity: rings weigh down lipid
At low temperatures, it increases fluidity.

Cholesterol maintains the cell fluidity no drastic shift from solid to liquid

Question 11

How do proteins serve the cell?

Answer 11

1. Transporters
2. Receptors
3. Enzymes
4. Anchors

Question 12

Two categories for membrane proteins

Answer 12

Integral membrane proteins: are permanently associated with the cell and cannot be separated from the cell without destroying it.

Peripheral membrane proteins: are temporarily associated with the lipid bilayer through weak covalent bonds

Question 13

Role of integral membrane proteins:

Answer 13

Transmembrane Proteins span the entire lipid bilayer.
- interacts with signaling molecules
- Interacts with the proteins in the cytoplasm

(Draw out the regions )

Question 14

Experimental proof that proteins move through the cell membrane

Answer 14

Experiment: Fluorescence recovery after bleach is a process where a small area of the cell membrane is bleached while the proteins are dyed. If the bleached part becomes dyed then the proteins traveled there. That is what happened.