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Cfe Advanced Higher Biology - Unit 1 > 1.3 MEMBRANE PROTEINS > Flashcards

1.3 MEMBRANE PROTEINS Flashcards

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1
Q

What is the cell membrane made up of?

A

A bilayer of phospholipids and proteins

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2
Q

Why is the membrane described as semi-permeable?

A

It only allows certain molecules to enter/exit the cell

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3
Q

What does the phospholipid bilayer act as a barrier to?

A

Ions and most uncharged polar molecules

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4
Q

Give two examples of small molecules that can pass through the phospholipid bilayer?

A

Oxygen and Carbon Dioxide

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5
Q

What types of proteins control ion concentration and concentration gradients?

A

Transmembrane proteins such as channels and transporters

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6
Q

Why do different cell types/compartments have different channel and transporter proteins?

A

To allow them to perform specialised functions

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7
Q

What type of transport are channel proteins involved in?

A

Passive transport

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8
Q

Give an example of a channel protein.

A

Aquaporin

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9
Q

What is the benefit of having gated channel proteins?

A

Allows for control over the rate of diffusion

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10
Q

What are ligand-gated channels?

A

Channels controlled by signal molecules

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11
Q

What are voltage-gated channels?

A

Channels controlled by changes in ion concentrations

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12
Q

What is the purpose of transporter proteins?

A

To change conformation in order to transport molecules across a membrane

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13
Q

Give an example of a facilitated transporter protein.

A

Glucose symport

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14
Q

Do facilitated transporter proteins require energy?

A

No because they are a passive form of transport

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15
Q

Give an example of an active transporter protein.

A

Na/KATPase

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16
Q

What provides the energy for the conformational change in active transporter proteins?

A

Energy from hydrolysis of ATP

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17
Q

What is hydrolysis?

A

Energy stored in high-energy bond is released

18
Q

What is the purpose of signal transduction?

A

To convert an extracellular chemical signal to a specific intracellular response

19
Q

Give four possible intracellular responses brought about by signal transduction.

A

Activation of a G protein, change in uptake/secretion of molecules, rearrangement of cytoskeleton, activation of proteins which regulate gene transcription

20
Q

What is a G protein?

A

A molecular switch involved in transmitting extracellular signals within the cell

21
Q

What does the sodium potassium pump do?

A

Transports ions against a steep concentration gradient

22
Q

What is the sodium potassium pump’s energy source?

A

ATP

23
Q

What does the pump have an affinity for inside the cell?

A

Sodium ions

24
Q

What happens after ions bind to the pump?

A

Phosphorylation by ATP causes a conformational change

25
Q

What is the result of the conformational change of the pump?

A

Its ion affinity changes and the ions previously bound are released on the other side of the membrane

26
Q

What does the pump have an affinity for outside the cell?

A

Potassium ions

27
Q

What is the result of dephosphorylation of the pump?

A

Conformational change

28
Q

What is the ratio of sodium:potassium transported by the pump?

A

3:2 (3 sodium ions out, 2 potassium ions in)

29
Q

What is another name for the sodium potassium pump?

A

Na/KATPase

30
Q

Give three functions of Na/KATPase

A

Generation of ion gradient for glucose symport in small intestine, generation/maintenance of ion gradient for resting potential in neurons, generation of ion gradient in kidney tubules

31
Q

Up to what % of human metabolic rate does maintenance of ion gradient by Na/KATPase account for?

A

Up to 25%

32
Q

What is nerve transmission?

A

A wave of depolarisation of the resting potential of a neuron

33
Q

What is resting potential?

A

The membrane potential of a neuron that is not transmitting signals

34
Q

What stimulates a neuron?

A

A signal molecule

35
Q

Give an example of a signal molecule.

A

Neurotransmitter

36
Q

How does the signal molecule stimulate the neuron?

A

Triggers the opening of a ligand-gated ion channel at a synapse

37
Q

What is the result of the ligand-gated ion channel opening?

A

If sufficient ion movement occurs, voltage-gated ion channels open

38
Q

What is the result of voltage-gated ion channels opening?

A

The effect travels along the length of the nerve in a wave of depolarisation

39
Q

What happens once the wave of depolarisation has passed?

A

The channel proteins close and others open to restore the resting potential

40
Q

How is the resting potential restored?

A

Ions move in the opposite direction (compared to the wave of depolarisation)

Cfe Advanced Higher Biology - Unit 1 (6 decks)

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