Forces Acting Across the Membrane Flashcards

1
Q

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

A

Ions

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2
Q

Why can membranes be described as dynamic?

A

They are always being formed and maintainedORDismantled and metabolised

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3
Q

Why are membranes described as flexible?

A

Fatty acids in vivo behave like oil and can stretch

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4
Q

What does the membrane insulating against?

A

Electrical charges - so prevents the movement of electrical charges

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5
Q

What type of membrane protein are receptors?

A

Membrane spanning

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6
Q

What are the functions of peripheral proteins?

A

Anchor the membrane to the intracellular cytoskeletonThey connect the cell to the extracellular matrix Performs signalling functions within the cell

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7
Q

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

A

A greater cell activity

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8
Q

What are extracellular glycoproteins and glycolipids responsible for?

A

Self vs non-self recognition

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9
Q

What is defined as the electrochemical gradient?

A

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

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10
Q

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

A

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)

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11
Q

What makes a molecule diffuse easily across a membrane?

A

Small, hydrophobic/lipophilic, uncharged

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12
Q

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

A

They are lipophilic

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13
Q

What does H2O pass through in the cell?

A

Aquaporins

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14
Q

What causes ligand gated channels to open?

A

Chemicals such as neurotransmitter or hormones

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15
Q

What is meant by the membrane potential?

A

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

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16
Q

When does a carrier act as an ATP ase?

A

When the electrochemical gradient opposes the movement of ions or he moleculeThe carrier protein hydrolyses the ATP releasing energy

17
Q

When is ATP hydrolysed in the sodium potassium pump?

A

When expelling sodium from the cellAn inorganic phosphate remains attached to the protein

18
Q

What is osmotic effect determined by?

A

PARTICLES - not molecules as they could dissociate

19
Q

What is the measurement of osmolarity?

A

Osmoles

20
Q

What is the osmolarity of blood?

A

It is taken as 300 (rounded from 285)

21
Q

What does cell wall volume depend on?

A

Non-penetrating particles - tonicity