Lecture 2 Membrane Transport Mechanisms

Question 1

Kinetic Energy

Answer 1

Molecules will have movement until it encounters another particle and change direction.
Don’t have to put E into system

Question 2

Osmosis

Answer 2

Movement of water across membrane without putting E into system
High conc to low conc
Only water can cross

Question 3

Osmotic Pressure

Answer 3

Semipermeable membrane - only some things can get through, allowing water through the diphram

Question 4

Dynamic Equilibrium

Answer 4

molecules will be entering and leaving at same rate

Question 5

3 critical parts of cell fluid

Answer 5

Sodium, Potassium and Chloride

Question 6

Sodium highest

Answer 6

outside cell

142 conc

Question 7

Potassium highest

Answer 7

inside cell

140 conc

Question 8

Chloride highest

Answer 8

outside cell

103 conc

Question 9

3 Energy independent mechanism for crossing cell membrane

Answer 9

1. Diffusion
2. Osmosis
3. Facilitated Diffusion

Question 10

Diffusion

Answer 10

High conc to low conc. No membrane required, but can be.

Ex. Perfume, high conc (on you) to low conc (person walking by)

Question 11

Osmosis

Answer 11

Movement of water molecules across semi-permeable membrane

Question 12

Facilitated Diffusion

Answer 12

Requires carrier proteins
No Energy required
Low conc to high

Question 13

4 Types of Mechanisms to cross cell membranes that require channels

Answer 13

1. Aquaporins
2. Ion channels
3. Ligand gated
4. Voltage gated

Question 14

Channels

Answer 14

are proteins that create pathways through cell membrane
Ex. Channel proteins
Very transient, depends on need of cell

Question 15

Non-gated channels

Answer 15

Always open

2 types 1. Aquaporins 2. Ion channels

Question 16

Gated channels

Answer 16

May open or close at any time, voltage required

2 types 1. Ligand 2. Voltage

Question 17

Ligand gated

Answer 17

Requires a signal molecule to open

Question 18

Voltage gated

Answer 18

When voltage changes, they open. Critical for membrane potentials

Question 19

Mechanisms for Crossing cell membranes Energy dependent

Answer 19

1. Active transport
   - Primary - requires ATP
   - Secondary - requires multiporters

Question 20

Active Transport

Answer 20

Energy typically comes from ATP
Defying entropy
Primary and Secondary

Question 21

Primary Active Transport

Answer 21

Requires ATP at site of transportation
ATPases have enzyme that can split ATP to get E
Many types of ATPases, each responsible for something different. This happens first, then secondary

Question 22

Secondary Active Transport

Answer 22

Requires multiporters
2 types 1. Symporters - cotransporters
2. Antiporters - countertransporters or exchangers

Question 23

Multiporters

Answer 23

Proteins that will transport more than one solute at a time

Question 24

2 Types of Multiporters

Answer 24

1. Symporters

2. Antiporters

Question 25

Symporters

Answer 25

2 sometimes 3 in the same direction at the same time

Question 26

Antiporters

Answer 26

Transports 2 or 3 different in different directions

Question 27

Diffusion

Answer 27

Movement of particles from area of high conc to low conc Depends on kinetic energy of particles rather than external energy Difussion across biphospholipid layer

Question 28

Particles that diffuse across biphospholipid layer

Answer 28

Oxygen, carbon dioxide, nitrogen, alcohols can diffuse readily across biphospholipid layer

Question 29

3 Factors affecting rate of diffusion

Answer 29

1. proportional to concentration difference across membrane 2. Membrane electric potential (Nernst potential) 3. Pressure difference

Question 30

Osmosis

Answer 30

Diffusion of solvent (water) across a semipermeable membrane

Question 31

Facilitated Diffusion

Answer 31

Requires uniporter carrier protein Vmax Used by glucose, amino acids

Question 32

Uniporter carrier protein

Answer 32

Used in facilitated diffusion | Carry one type of particle with the diffusion gradient

Question 33

Vmax

Answer 33

Limits the transporter, can be overwhelmed | Ex. If you eat 15 donuts, will be sugar in urine

Question 34

2 things that use Facilitated diffusion

Answer 34

Glucose, amino acids

Question 35

3 Types Non-gated channels

Answer 35

1. Aquaporins 2. Potassium channels with selectivity filters with carbonyl oxygens 3. Sodium channels

Question 36

Why can't sodium use potassium's channel

Answer 36

Potassium is larger, so it would fit. But there is a selective filter that doesn't let it through

Question 37

Active transport

Answer 37

``` Movement of particles against concentration gradient Requires energy 2 types Primary Secondary ```

Question 38

Primary active transport

Answer 38

Energy is derived directly from breakdown of ATP | Utilizes ATPase transporters

Question 39

Secondary transport

Answer 39

Energy is derived secondarily from concentration differences of molecular or ionic substances created originally by primary active transport Utilizes multiporters

Question 40

Na+ K+ pump uses

Answer 40

Primary active transport | Most common in nerve cells