Membranes - Chapter 7

Question 1

Functions of Membranes

Answer 1

1. Selectively permeable barrier
2. Protein Anchor
3. Energy Metabolism

Question 2

Membrane Structure

Answer 2

Phospholipid Bilayer

Question 3

Membrane Fluidity

Importance?

Answer 3

• Phospholipids more laterally and sometimes transversely

- Important for membrane permeability and activity of embedded proteins

Question 4

Cholesterol in animal cell membranes do what…..

Answer 4

Hinder tight packing (more fluid)

Pack more tightly at low temps

Question 5

2 Types of membrane proteins

Answer 5

Peripheral - bound to membrane surface - hydrophilic bc face cytoplasm and outside of cell

Integral proteins - spam membrane (transmembrane proteins) - hydrophobic

Question 6

Transmembrane receptor proteins

Answer 6

Attachment site for other cells

Recognition, communication, signal transduction

Question 7

Membrane transport proteins

Answer 7

Polar and ionic molecules transported by specific transmembrane channel or carrier proteins

Question 8

Passive diffusion

Answer 8

Region of high concentration to low concentration (DOWN concentration gradient)
NO energy

Question 9

Osmosis

Answer 9

Diffusion of water across selectively permeable membrane
PASSIVE
DOWN cgrad.
Aquaporins

Question 10

Isotonic Solution

Answer 10

Solute concentration on both sides of membrane is the same

NO water movement

Question 11

HYPERtonic Solution

Answer 11

• When external environment has higher solute concentration relative to cytoplasm
  → cells loose water → shrink

-Shriveled/plasmolyzed

Question 12

HYPOtonic solution

Answer 12

• When external environment has a lower solute concentration relative to cytoplasm
  → cells gain water → burst

-Turgic/Lysed

Question 13

Facilitated diffusion

Answer 13

Specific transport proteins (ie: channel protein) increase rate of diffusion
DOWN conc grad

Question 14

Active transport

Answer 14

Against conc grad.
Requires energy (ATP)

Question 15

Bulk transport

Answer 15

Lrg. substances transported across membrane via membrane-bound vesivles
Vesicle and cell membranes fuse

Question 16

Exocytosis

Answer 16

Export of large molcules from cell

Question 17

Endocytosis

Answer 17

ENTRANCE of lrg molecules into cell

Question 18

Entrance on non polar molecules

Answer 18

Dissolve in the lipid bilayer easily since they are hydrophobic

Question 19

Entrance of ions/polar molecules

Answer 19

Hydrophillic makes them not pass the fatty acids section alone - they need help

Question 20

Channel Proteins - how do they work

Answer 20

channel proteins, function by having a hydrophilic channel that certain molecules or atomic ions use as a tunnel through the membrane

Question 21

carrier proteins

Answer 21

carrier proteins, hold onto their passengers and change shape in a way that shuttles them across the membrane