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Advanced Higher Biology > Unit 1 - Membrane Proteins > Flashcards

Unit 1 - Membrane Proteins Flashcards

1
Q

What are integral proteins?

A

Proteins that have one or more segment embedded in the phospholipid bilayer

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2
Q

What are transmembrane proteins?

A

Proteins which span across the membrane and act as channels or transporters of ions

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3
Q

What are peripheral proteins?

A

Proteins which are temporarily bound to either surface of the membrane

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4
Q

What is facilitated diffusion?

A

The passive transport of substances across the membrane through specific proteins

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5
Q

What are transporter proteins?

A

Membrane proteins involved in the movement of ions, small molecules and macromolecules across a membrane

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6
Q

What are gated channel proteins?

A

Channel-forming proteins controlled by signalling molecules or ion concentration.

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7
Q

What are ligand-gated channels?

A

Transmembrane protein channels controlled by the binding of signal molecules

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8
Q

What are voltage-gated proteins?

A

Transmembrane proteins that form ion channels, activated by the changes in the electrical membrane potential

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9
Q

What is the electrochemical gradient?

A

A gradient of electrochemical potential, consisting of difference in solute concentration and difference in charge

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10
Q

What is the membrane potential?

A

An electrical gradient that forces ions to move passively in one direction

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11
Q

What is the sodium-potassium pump?

A

A protein that removes 3 sodium ions and takes 2 potassium ions into the cell during a cycle of action

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12
Q

What is a glucose-symport?

A

An integral membrane protein involved in transport of glucose and sodium ions across the membrane

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13
Q

What does the plasma membrane control?

A

Entry and exit of materials

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14
Q

What is the plasma membrane composed of?

A

-Phospholipids
-Proteins

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15
Q

What are the 2 regions of a phospholipid and what are their properties i.e. charge?

A
  • Head region ( charged, hydrophilic, attracted to water )
  • Tail region ( uncharged, hydrophobic, repelled by water )
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16
Q

What gives the membrane a fluid quality?

A

Phospholipids which are constantly changing position

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17
Q

Examples of proteins found in the membrane

A
  • Active transport proteins
  • Channel forming proteins
  • Enzymes
  • Receptors
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18
Q

Examples of integral proteins

A
  • Channels
  • Transporters
  • Receptors
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19
Q

What do integral proteins interact with?

A

The hydrophobic region of membrane phospholipids

20
Q

What holds integral proteins within the phospholipid bilayer?

A

Regions of hydrophobic R groups allow strong hydrophobic interaction, holding them in the membrane

21
Q

How are peripheral proteins bound to the surface of the membrane?

A

They have hydrophilic R groups on their surface, so can be bound by ionic and hydrogen bonds interactions

22
Q

What molecules does the phospholipid bilayer act as a barrier to?

A

Ion and most uncharged polar molecules

23
Q

How do oxygen and carbon dioxide pass through the membrane?

A

Diffusion

24
Q

What are the proteins involved in transporting substances?

A
  • Channel proteins ( ligand-gated, voltage-gated)
  • Transporter proteins
  • Protein pumps
25
Q

What proteins use the method of facilitated diffusion?

A

Transporter proteins and channel proteins

26
Q

What are channels?

A

Multi-subunit proteins with the subunits arranged to form water-filled pores

27
Q

What do gated proteins respond to?

A

Stimulus ( Chemical, Electrical )

28
Q

How does the ligand-gated channel open?

A

When correct signal molecules bind, gate open allowing ions to flow through

29
Q

How do transporter proteins work?

A

Transporter proteins bind to specific substances which are to be transported and undergo a conformational change to transfer the solute across the membrane

30
Q

Why do transporter proteins alternate between 2 conformations?

A

So that the binding site is sequentially exposed on one side for the bilayer then the other

31
Q

What are transporter proteins coupled to an energy source?

A

Pumps

32
Q

What is required for protein pumps to transfer substances?

A

A source of metabolic energy

33
Q

What do some active transport proteins do to provide energy?

A

Hydrolyse ATP directly

34
Q

What are the proteins that hydrolyse ATP directly?

A

ATPases

35
Q

How is the electrochemical gradient formed?

A

The concentration gradient and electrical potential difference are combined

36
Q

What does the electrochemical gradient determine?

A

The transport of the solute carrying a net charge

37
Q

What is the concentration gradient?

A

The difference in concentration of a solute across the plasma membrane

38
Q

When is an electrical potential difference/membrane potential created?

A

When there is a difference in electrical charge on the two sides of the membrane

39
Q

What does the sodium potassium pump use to establish and maintain ion gradients?

A

Energy from the hydrolysis of ATP

40
Q

How does Na/K-ATPase transport ions?

A

Transports ions against a steep concentration gradient using energy directly from ATP hydrolysis

41
Q

The process of sodium potassium pump?

A
  • Pump has high affinity for sodium inside the cell, binding occurs
  • Pump hydrolyses ATP and phosphate attaches to pump
  • Phosphorylation by ATP causes conformation of the protein to change
  • Affinity for sodium ions decrease and 3 ions are released outside cell
  • Pump now has high affinity for potassium outside the cell therefore 2 ions bind to pump
  • Dephosphorylation occurs which causes conformation of protein to change
  • Potassium ions taken into cell and affinity returns to start
42
Q

What does the sodium-potassium pump account for a high proportion of?

A

High proportion of the basal metabolic rate (up to 25% in humans)

43
Q

What does the sodium-potassium pump generate in the small intestine?

A

A sodium ion gradient across the plasma membrane which drives active transport of glucose

44
Q

What is the glucose transporter called?

A

Glucose symport

45
Q

What does the glucose symport do?

A

Transports sodium ions and glucose at the same time and in the same direction.

Advanced Higher Biology (8 decks)

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