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AH Biology > Membrane Proteins > Flashcards

Membrane Proteins Flashcards

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1
Q

What describes the structure of the plasma membrane?

A

Fluid mosaic model

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2
Q

Some integral proteins are…

A

Transmembrane proteins

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3
Q

What are transmembrane proteins?

A

Span entire width of the membrane e.g. channels, transporters and many receptors

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4
Q

What is facilitated diffusion?

A

Passive transport of substances across the membrane through specific transmembrane proteins, used by channel and transporter proteins

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5
Q

what are the proteins involved in transporting substances?

A

Channel
Transporter
Protein pumps

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6
Q

Function of plasma membrane

A

Surrounds cells and controls entry and exit of materials

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7
Q

Plasma membrane is composed of…

A

Phospholipids and proteins

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8
Q

What gives the membrane it’s fluid quality?

A

Phospholipids are constantly changing position

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9
Q

Structure of phospholipids

A

Charged, hydrophilic head and uncharged, non-polar, hydrophobic tail

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10
Q

Integral proteins react extensively with…

A

hydrophobic region of membrane phospholipids

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11
Q

Membrane proteins are either…

A

Integral (within membrane) or peripheral (on surface of membrane)

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12
Q

How are integral proteins held within the phospholipid bilayer?

A

Regions of hydrophobic R groups allow strong hydrophobic interactions

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13
Q

Peripheral proteins have…

A

Hydrophilic R groups on their surface and are bound to the surface of membranes mainly by ionic and hydrogen bond interactions

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14
Q

Many peripheral proteins interact with…

A

The surface of integral proteins

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15
Q

The phospholipid bilayer is a barrier to…

A

Ions and most uncharged polar molecules

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16
Q

Small molecules such as oxygen and carbon dioxide can pass through membrane by…

A

Simple diffusion

17
Q

What are channel proteins?

A

Multi-subunit proteins with subunits arranged to form water filled pores that extend across membrane

18
Q

Most channel proteins in plants and animals are…

A

Highly selective

19
Q

Some channel proteins are…

A

Gated- change conformation to allow/prevent diffusion

20
Q

What are ligand-gated channels controlled by?

A

Binding of signal molecules, correct binds>gate opens>allows flow of ions through, have chemical stimulus

21
Q

What are voltage-gated channels controlled by?

A

Changes in ion concentration, have electrical stimulus

22
Q

How do transporter proteins transfer the solute across the membrane?

A

Bind to specific substance to be transported and undergo conformational change

23
Q

Transported proteins alternate between… so that…

A

2 conformations, the binding site for the solute is sequentially exposed on one side of the membrane and then the other

24
Q

What are pumps that carry out active transport?

A

Transporter proteins coupled to an energy source

25
Q

Active transport uses..

A

Pump proteins that transfer substances across the membrane against their concentration gradient so require a source of metabolic energy

26
Q

Some active transport proteins…

A

Hydrolyse ATP directly using ATPases to provide energy for the confrormational change require to move substances across the membrane

27
Q

What does the electrochemical gradient determine?

A

Transport of a solute e.g. where and how far it goes

28
Q

What is the concentration gradient?

A

Difference in concentration of a solute across the plasma membrane

29
Q

What is the electrical potential difference?

A

Created when there is a difference in electrical charge on the 2 sides of a membrane

30
Q

For a solute carrying a net charge, what combines to form the electrochemical gradient?

A

Concentration gradient and electrical potential difference

31
Q

What does the sodium-potassium pump account for?

A

A high proportion of the basal metabolic rate in many organisms

32
Q

Sodium-potassium pump actively transports…

A

3 sodium ions out and 2 potassium ions in cell (per ATP hydrolysed)

33
Q

Function of ATP hydrolysis in SPP

A

Establishes and maintains ion gradient

34
Q

Ion pumps such as the SPP transports ions…

A

Against a steep concentration gradient using energy directly from ATP hydrolysis

35
Q

How does the SPP work?

A
  1. Pump has high affinity for sodium ions inside cell so binding occurs
  2. Pump hydrolyses ATP and phosphate attaches (phosphorylation by ATP), conformation of protein changes
  3. Affinity for sodium ions decreases so released outside cell
  4. Pump has high affinity for potassium ions outside cell so binding occurs
  5. Dephosphorylation causes the protein to change conformation
  6. Potassium ions are taken into cell and affinity returns to start
36
Q

In intestinal epithelial cells of the small intestine, the SPP generates a…

A

sodium ion gradient across the plasma membrane, this gradient drives the active transport of glucose

37
Q

What is the protein that transports glucose called?

A

Glucose symport

38
Q

Glucose symport is responsible for…

A

The active transport of glucose and sodium ions at the same time and in the same direction.

39
Q

Sodium ions enter the cell down their concentration gradient and the simultaneous transport of…

A

Glucose pumps glucose into the cell against its concentration gradient

AH Biology (13 decks)

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