Session 3: Membrane Permiability Flashcards Preview

Sem 1: Pharamacology and Physiology > Session 3: Membrane Permiability > Flashcards

Flashcards in Session 3: Membrane Permiability Deck (26):
1

What is a semi-permisible membrane?

A layer through which only allowed substances can pass

2

What types of molecules can pass a phospholipid bilayer?

- hydrophobic
- small, uncharged, polar molecules

3

What types of molecules cannot pass a phospholipid bilayer?

- large, uncharged, polar molecules
- ions

4

Give an example of a molecule which can pass a phospholipid bilayer.

- oxygen
- carbon dioxide
- water
- urea
- glycerol
- benzene
- nitrogen

5

Give an example of a molecule which cannot pass a phospholipid bilayer.

- glucose
- sucrose
- protons

6

TRUE OR FALSE: molecules with a small permeability coefficient have a high permeability.

False: molecules like Na+ have a very low permeability coefficient (10^-2) and is hardly permeable

7

What two factors influence passive transport?

1. Permeability
2. Concentration gradient

8

TRUE OR FALSE: rate of passive transport doesn't increase linearly with increasing concentration gradient

False

9

Give 3 reasons why transport processes are so important.

1. Maintenance of intracellular pH
2. Regulation of cell volume
3. Maintenance if ionic composition
4. Expulsion of metabolic waste and toxic substances
5. Generation of ion gradients necessary for AP

10

Why is a rotating carrier or reciprocating carrier (flip-flop) not considered the correct model for transport proteins.

Thermodynamically unlikely

11

What does it mean if +deltaG is positive?

It's active transport

12

What does it mean if -deltaG is negative?

Passive

13

Define active transport.

Allows the transportation of ions or molecules against an unforgivable concentration gradient. Required energy (either directly or indirectly from ATP)

14

Is there more sodium ions inside or outside the cell?

Outside

15

Is there more chloride ions inside or outside the cell?

Outside

16

Is there more calcium ions inside or outside the cell?

Outside

17

Is there more potassium ions inside or outside the cell?

Inside

18

What is a primary transporter?

Uses ATP directly

19

What is a secondary transporter?

Uses energy from ATP indirectly e.g. NCX

20

Give an example of a primary active transporter.

Calcium ATPase (PMCA)

21

Define unimport.

Movement of one molecule

22

Define symport.

Co-transport. Movement of 2 molecules in the same direction.

23

Define antiport.

Co-transport. Movement of 2 molecules in different directions.

24

Give an example of an antiport transporter.

NXC

25

Which ions and how many move using an NXC transporter?

3 sodium ions move out of the cell, 2 potassium ions move into the cell

26

What transporter is important for creating a high intracellular potassium concentration?

- MAINLY membrane permeability for potassium ions
- secondary: sodium pump however this only generates 5-10 mV through electrogenic pump activity