CP 1

Question 1

Describe the fluid mosaic model in terms of membrane structure

Answer 1

• Lipid bilayer with imbedded membrane proteins
• Membrane & lipid = 50:50 (held by H bonds)
• Barrier to entry/exit of polar substances
• Proteins are regulating “gatekeepers”

Question 2

How does the molecular structure of the membrane result in selective permeability

Answer 2

Permeability is determined by membrane proteins for transport, electrochemical gradient, permeability of molecules to membrane

Question 3

How does the composition of different fluid compartments act to store energy?

Answer 3

Cells use ~30% of resting energy to maintain conc and electrical gradients - these gradients represent stored energy

Question 4

What is the function of the cell membrane?

Answer 4

Provides a protective barrier that surrounds cytoplasm of cell

Question 5

What are integral proteins

Answer 5

• Extend into or completely across membrane

- Amphipathic

Question 6

What are peripheral proteins

Answer 6

• Proteins attached to either inner or outer surface of membrane
• Easily removed

Question 7

What are integral proteins?

Answer 7

• Extend into or completely across membrane

- Amphipathic: nonpolar amino acids in helices in core / hydrophilic ends interact with aqueous solution

Question 8

What are peripheral proteins?

Answer 8

• Proteins attached to either inner or outer surface of membrane
• Easily removed

Question 9

What are the functions of membrane proteins? (6)

Answer 9

• ION CHANNELS
• TRANSPORT PROTEINS
• Receptor proteins
• Cell identity markers
• Links to other cells
• Act as enzymes

Question 10

What are the functions of membrane proteins? (6)

Answer 10

• ION CHANNELS
• MEDIATE PROTEIN TRANSPORT
• Receptor proteins
• Cell identity markers
• Links to other cells
• Act as enzymes

Question 11

What is the lipid bilayer permeable to?

Answer 11

• Nonpolar, uncharged molecules (O2, N2, benzene)
• Lipid-soluble molecules (fatty acids, etc.)
• Small uncharged molecules (H2O, CO2, urea, glycerol)

Question 12

What is the lipid bilayer impermeable to?

Answer 12

• Large uncharged polar molecules

- Impermeable ions (Na, K, Cl, Ca, H)

Question 13

What are the laws of diffusion?

Answer 13

Transport from high to low conc until equilibrium reached

• Greater the difference in conc = faster
• Larger/thicker = slower
• Smaller distance = faster

Question 14

Non-charged molecules will diffuse up/down conc gradient?

Answer 14

Down

Question 15

The movement of ions is determined by_?

Answer 15

Sum of electrical and chemical gradient (sometimes these are in opposite) = electrochemical gradient

Question 16

What makes an electrical gradient/membrane potential?

Answer 16

Cells can maintain a difference in charged ions between inside and outside of membrane - due to selective permeability