Topic 1.4: Membrane Transport Flashcards Preview

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Flashcards in Topic 1.4: Membrane Transport Deck (19)
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1

Properties of Membranes (2)

a) Semi-permeable (only certain things can cross)
b) Selective (membranes can regulate material passage)

2

Types of membrane transport (2)

a) Active (Requires ATP, down concentration gradient)
b) Passive (No ATP, against concentration gradient)

3

Passive transport

a) Simple diffusion
b) Facilitated diffusion
c) Osmosis

4

Simple diffusion

a) Net movement of molecules along a concentration gradient
b) Involves small lipophilic molecules (O2, CO2)

5

Osmosis

Net movement of water molecules across a semi-permeable membrane against a concentration gradient.

6

Hypertonic solution

a) High solute concentration
b) Gains water

7

Hypotonic solution

a) Low solute concentration
b) Loses water

8

Isotonic solution

a) Same solute concentration
b) No net water flow

9

Negative effects of uncontrolled osmosis on cells

a) Crenation (Hypertonic)
b) Lysis (Hypotonic)

10

Facilitated diffusion

a) Transport of molecules via a membrane protein
b) Involves large / charged molecules.

11

Carrier proteins

a) Undergo a conformational change to translocate the solute
b) ATP presence
c) Slow rate of transport

12

Channel proteins

a) Ions may cross through a pore
b) Along a concentration gradient.
c) Fast rate of transport

13

Active transport

a) Transport against a concentration gradient
b) Requires ATP

14

Process of active transport (3)

a) Molecule binds to a transmembrane protein pump
b) Hydrolysis of ATP causes a conformational change.
c) The molecule translocates across the membrane.

15

Sodium-Potassium Pumps (6)

a) 3 Na+ bind to the sodium-potassium pump.
b) A phosphate group is transferred to the pump via the hydrolysis of ATP
c) The pump undergoes a conformational change, translocating Na+ across the membrane.
d) This exposes two K+ to the extracellular suface of the pump.
e) The phosphate group is released
f) Translocates K+ across the membrane.

16

Vesicular transport

a) Endocytosis
b) Exocytosis

17

Endocytosis

Large substances internalised within a vesicle by invagination.

18

Exocytosis

Materials released from cells via vesicles, which fuse with the membrane.

19

Intracellular vesicles

a) rER
b) Golgi Apparatus
c) Plasma membrane