Cell membranes and Molecular movement

Question 1

Cell membrane (what it is and structure)

Answer 1

-semi-permeable barrier that separates the inside of the cell with the outside

Structure

• phospholipid bilayer
• contains proteins
• contains cholesterol (animal cells)
• contains carbohydrates
• dynamic

Question 2

Phospholipid bilayer

Answer 2

• phosphate+glycerol+2 fatty acid tails

- hydrophilic head, hydrophobic tails

Question 3

Contains proteins (types and functions)

Answer 3

types:

• peripheral: inner or outer surface of membrane
• integral: embedded in membrane
• transmembrane: penetrate membrane completely

Functions:

• transport (channels)
• recognition (name tags)
• receptor (communication)
• adhesion (attachment/ support)
• enzymes (workers)

Question 4

Contains cholesterol (function and what happens in extreme temps)

Answer 4

function: regulates fluidity

• cold –> prevents from becoming too rigid
• hot –> prevents from moving too much

Question 5

Contains carbohydrates (what it is and functions (3))

Answer 5

• glycocalyx: carbohydrate coat

- functions: adhesion, barrier, recognition

Question 6

Dynamic

Answer 6

fluid mosaic model

Question 7

Cell membrane (functions and example)

Answer 7

• allows each cell to act as its own unit
• regulates movement of molecules in and out of the cell (selective permeability based on size, charge, shape, lipid solubility)
• provide an anchor for enzymes to coordinate cell activities

ex: ATP production

Question 8

Membrane transport (what it is and types)

Answer 8

-allows nutrients, waste, water, etc in and out of the cell in a controlled manner
Types: passive transport, active transport

Question 9

Passive transport (what it is and types)

Answer 9

• does not require energy
• movement of molecules from high to low concentration

Types:

• simple diffusion
• facilitated diffusion
• osmosis

Question 10

Simple diffusion aka dialysis (what it is and examples)

Answer 10

• movement of solutes across a membrane from high to low concentration
  ex: lipid soluble compound, dissolved gasses

Question 11

Types of facilitated diffusion

Answer 11

carrier mediated and protein channels

Question 12

Carrier Mediated (what it is and example)

Answer 12

-transported protein facilitates movement of a solute from high to low concentration
-usually specific, 1 transporter –> 1 molecule
EX: glucose carrier protein

Question 13

Protein channels (what it is and example)

Answer 13

-transmembrane proteins –> channels allowing molecules to move through
-passage depends on size and charge
EX: water soluble compounds, ions

Question 14

Osmosis

Answer 14

movement of water across a membrane from a high to low concentration of water

Question 15

Osmotic pressure (what it is and when it happens)

Answer 15

• the force of water generated by a solute concentration

- When? solutes: not permeable, water: freely permeable

Question 16

A closer look at osmotic pressure

Answer 16

• measure of how strong a solution draws in water

- high osmotic pressure=more water draw

Question 17

Osmolality (what it is, units, determined by)

Answer 17

-the measure of osmotic pressure

• Units
• osmole: 1 mole of solute dissolved into 1 liter of water
• mole: 6.02x10^23 particles
• determined by the number of particles not concentration
• osmolality= concentration x # of particles

Question 18

Driving force for passive transport

Answer 18

-electrochemical

• Electrical
  
  • membrane potential: difference in electrical potential across membranes
  • like charges repel, opposite charges attract
• Chemical
• concentration gradients

Question 19

factors affecting diffusion rates

Answer 19

1. distance: shorter –> faster
2. gradient size: larger distance –> faster
3. molecular size: smaller –> faster
4. Temperature: hotter –> faster

Question 20

Active transport (what is required, direction molecules move, types)

Answer 20

• requires energy (ATP) and a transporter protein
• movement of molecules from low –> high concentration
• Types:
• primary active transport
• secondary active transport

Question 21

Primary active transport

Answer 21

• uses ATP and transporter to move molecules against concentration gradient
• EX: Na+/K+ pump

Question 22

Na+/K+ pump

Answer 22

• uses 1 ATP

- moves 3 Na+ out and 2 K+ in

Question 23

Secondary Active transport

Answer 23

• uses a concentration gradient (generated by primary active transport) to move molecules against their concentration gradient
• EX: Na+ concentration gradient produced by Na+/K+ pump drives glucose transport

Question 24

Cotransport

Answer 24

Same direction

Question 25

Countertransport

Answer 25

opposite direction

Question 26

Transporter proteins

Answer 26

Ion pumps: move ions (Na+/K+)

Exchange pumps: move 2 types of molecules at the same time