Chapter 2- Cell Membrane

Question 1

Cell Membrane

Answer 1

Made up of phospholipids, cholesterol, proteins.

Question 2

Phospholipid

Answer 2

lipid (fat) in cell membranes that contain glyceral backbon, phosphate group (polar/hydrophilic), and two fatty acid tails (non-polar/hydrophobic).

Bc it is amphipathic, spontaneously self-assembles into a bilayer when in an aqueous environment. Phospholipid head will face both aqueous environment (intracellular or extracellular), while the fatty acid tails will face each other.

Question 3

Cholesterol

Answer 3

• Amphipathic

- Interaction with cell membrane allows for better fluidity in phospholipid membrane

Question 4

Integral (transmembrane) Proteins

Answer 4

• Amphipathic
• traverse the entire bilayer
• Transport large polar molecules across cell membrane

Question 5

Receptor proteins

Answer 5

• Triggers secondary responses within cell.

- If receptor protein transmits a signal through the lipid bilayer, it is an integral receptor protein.

Question 6

Peripheral membrane protein

Answer 6

• Do not extend through the entire bilayer; Located on Periphery
• Hydrophilic
• Contain adhesion and cellular recognition proteins.

Question 7

Adhesion proteins

Answer 7

• attach cells to other cells (stick like tape)

- Act as anchors for the cytoskeleton.

Question 8

Cellular recognition proteins

Answer 8

• help cells recognize each other.

- interact with receptor proteins

Question 9

Fluidity of cell membrane affected by 3 things:

Answer 9

1. Temperature- as temperature goes ↑ increase fluidity
   while ↓ temperatures decrease fluidity.
2. Cholesterol- If temperature is ↑ fluidity decreases. If temperature is ↓ fluidity increases.
3. Degree of unsaturation- If the fatty acid is saturated then packed tightly. If unsaturated fatty acids then loosely packed because of double bonds causing kinks. (Trans-unsaturated is packed tighter than Cis- bc double bonds are on opposite side)