Forces Acting Across the Memrane Flashcards Preview

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Flashcards in Forces Acting Across the Memrane Deck (21):
1

What can pass through the capillary easily but not the cell membrane?

Ions

2

Why can membranes be described as dynamic?

They are always being formed and maintained

OR

Dismantled and metabolised

3

Why are membranes described as flexible?

Fatty acids in vivo behave like oil and can stretch

4

What does the membrane insulating against?

Electrical charges - so prevents the movement of electrical charges

5

What type of membrane protein are receptors?

Membrane spanning

6

What are the functions of peripheral proteins?

Anchor the membrane to the intracellular cytoskeleton

They connect the cell to the extracellular matrix

Performs signalling functions within the cell

7

What does an increased protein content in a cell usually correlate with?

A greater cell activity

8

What are extracellular glycoproteins and glycolipids responsible for?

Self vs non-self recognition

9

What is defined as the electrochemical gradient?

It is the combination of the difference in ion concentration and the difference in charge across a membrane.

It drives passive movement

10

How do you calculate the magnitude of diffusion (F)?

Kp x A x (C1-C2)

Where Kp is the permeability coefficient (measuring the ease at which a molecule can pass through a given membrane)

11

What makes a molecule diffuse easily across a membrane?

Small, hydrophobic/lipophilic, uncharged

12

Why don't CO2 and urea pass easily across the plasma membrane?

They are lipophilic

13

What does H2O pass through in the cell?

Aquaporins

14

What causes ligand gated channels to open?

Chemicals such as neurotransmitter or hormones

15

What is meant by the membrane potential?

The difference in charge between the inside and the outside of the cell - it creates a potential gradient down which ions flow

16

When does a carrier act as an ATP ase?

When the electrochemical gradient opposes the movement of ions or he molecule

The carrier protein hydrolyses the ATP releasing energy

17

When is ATP hydrolysed in the sodium potassium pump?

When expelling sodium from the cell
An inorganic phosphate remains attached to the protein

18

What is osmotic effect determined by?

PARTICLES - not molecules as they could dissociate

19

What is the measurement of osmolarity?

Osmoles

20

What is the osmolarity of blood?

It is taken as 300 (rounded from 285)

21

What does cell wall volume depend on?

Non-penetrating particles - tonicity