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Adv Bio Unit 1 > 1.3- Membrane Proteins > Flashcards

1.3- Membrane Proteins Flashcards

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Biology 101 flashcards
1
Q

What does the plasma membrane do?

A

surrounds cells and controls entry and exit of materials

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2
Q

The fluid mosaic model describes…

A

the structure of the plasma membrane

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3
Q

The plasma membrane is composed of…

A

proteins and phospholipids

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4
Q

The head region of a phospholipid is charged, therefore…

A

hydrophilic (attracted to water)

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5
Q

The tail region of a phospholipid is uncharged, and non-polar, therefore…

A

hydrophobic (repelled by water)

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6
Q

The phospholipids are constantly changing position, what does this give the membrane?

A

its fluid quality

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7
Q

The phospholipids are arranged into a ……… in the plasma membrane

A

bilayer

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8
Q

In the phospholipid the heads point ……. and the tails point ……..

A

heads point out and the tails point in

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9
Q

The cell membrane is embedded with proteins which form a ………..

A

patchy mosaic

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10
Q

Functions of the proteins that are found within the cell membrane:

A

active transport proteins, channel forming proteins, enzymes, receptors, attachment proteins for the cell cytoskeleton

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11
Q

Different types of protein in the plasma membrane

A

integral and peripheral

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12
Q

integral proteins

A

found within the membrane

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13
Q

Some integral proteins are transmembrane, what does this mean?

A

they span the entire width of the membrane

e.g. channels, transporters, receptors

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14
Q

integral membrane proteins interact with the ……. region of the membrane phospholipids

A

hydrophobic

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15
Q

peripheral proteins

A

found on the surface of the membrane

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16
Q

peripheral membrane proteins have …………. ….. groups on their surface and are bound to the ….. of the membranes by ……. and …… bonding

A

hydrophilic R groups on surface

bound to the surface of membranes by ionic and hydrogen bond

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17
Q

many peripheral membrane proteins interact with the surface of

A

integral membrane proteins

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18
Q

The phospholipid bilayer acts as a…

A

barrier to ions and most uncharged polar molecules

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19
Q

some small molecules like oxygen and carbon dioxide pass through the bilayer by

A

simple diffusion

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20
Q

many molecules pass through the membrane with the help of

A

proteins

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21
Q

Proteins involved with transporting substances

A

channel proteins (ligand and voltage)
transporter proteins
protein pumps

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22
Q

facilitated diffusion

A

the passive transport of substances across the membrane through specific transmembrane proteins

23
Q

proteins used in facilitated diffusion

A

channel proteins

transporter proteins

24
Q

to perform specialised functions, different cell types have different …… and …… proteins

A

channel and transporters

e.g. small intestine have glucose transporters

25
Q

channel proteins

A

are multi-subunit proteins with the subunits arranged to form water-filled pores across the membrane

26
Q

most channel proteins in animal and plant cells are highly…

A

selective

27
Q

some channel proteins are gated and change …… to allow/prevent …..

A

Some channel proteins are gated and change conformation to allow or prevent diffusion

28
Q

gated channel proteins respond to a stimulus which causes them to…

A

open or close

29
Q

gated channel proteins stimuli

A

ligand-gated (chemical)

voltage-gated ( electrical)

30
Q

ligand gated channels are controlled by the binding of

A

signal molecules

when the signal molecule binds the gate opens, allowing ions to flow through

31
Q

voltage gated channels are controlled by

A

changes in ion concentrations

32
Q

transporter proteins bind to the specific substance to be transported and undergo a……

A

conformational change to transfer the solute across the membrane

33
Q

transporters alternate between two ………. so that the binding site for the solute is sequentially exposed on one side of the bilayer, then the other

A

conformations

34
Q

Transporters alternate between two conformations so that the…

A

binding site for a solute is sequentially exposed on one side of the bilayer, then the other.

35
Q

active transport uses ……….. that transfer substances across the membrane against their …………

A

Active transport uses pump proteins that transfer substances across the membrane against their concentration gradient.

36
Q

pumps that carry out active transport are…

A

transporter proteins coupled to an energy source.

37
Q

For protein pumps to transfer substances what is required for active transport?

A

a source of metabolic energy (ATP)

38
Q

some active transport proteins ………… ATP directly to provide the energy for the conformational change required to move the substances across the membrane

A

hydrolase

39
Q

Proteins which hydrolase ATP directly are called

A

ATPases

40
Q

some active transport proteins hydrolase ATP directly to..

A

provide the energy for the conformational change required to move substances through the membrane

41
Q

For a solute carrying a net charge, the concentration gradient and the electrical potential difference combine to form…

A

the electrochemical gradient

42
Q

what two things combine to form the electrochemical gradient

A

the concentration gradient and the electrical potential difference

43
Q

electrochemical gradient

A

determines the transport of the solute i.e. how and where the solute goes

44
Q

concentration gradient

A

difference in concentration of a solute across the plasma membrane

45
Q

Electrical potential difference (membrane potential)

A

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

46
Q

ion pumps, (sodium-potassium pump) use energy from………… to establish and maintain ion gradients

A

the hydrolysis of ATP

47
Q

Ion pumps, such as the sodium-potassium pump, use energy from the hydrolysis of ATP to

A

establish and maintain ion gradients.

48
Q

what does the sodium potassium pump do?

A

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

49
Q

the sodium potassium pump transports 3…….. ions out of cells and 2…….. ions in

A

It actively transports 3 sodium ions out of cells and 2 potassium ions in.

50
Q

The maintenance of ion gradients by Na/K-ATPase accounts for a significant part of

A

basal metabolic rate

51
Q

The process of the sodium potassium pump

A
  1. The pump has high affinity for sodium ions inside the cell- binding occurs
  2. Pump hydrolyses ATP and phosphate attaches to it. Phosphorylation by ATP causes the conformation of the protein to change.
  3. The affinity for sodium ions decreases resulting in sodium being released outside of the cell.
  4. The pump now has high affinity for potassium ions outside the cell therefore binding occurs.
  5. Dephosphorylation occurs which causes the conformation of the protein to change.
  6. Potassium ions are taken into the cell and the affinity returns to the start.
52
Q

In intestinal epithelial cells the sodium potassium pump generates a ……… across the plasma membrane.

A

sodium ion gradient

This gradient drives the active transport of glucose.

53
Q

symporter

A

transports molecules across the plasma membrane at the same time

Adv Bio Unit 1 (6 decks)

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