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Biology AS > Membranes > Flashcards

Membranes Flashcards

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1
Q

What makes up a membrane?

A

Phospholipids and proteins make up the phospholipid bilayer

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2
Q

How wide are membranes?

A

7nm

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3
Q

What are membranes seen as on an electron microscope?

A

Two dark bands

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4
Q

What are the four functions of membranes?

A
  1. Selectively permeable barrier
  2. Taking up nutrients
  3. Secreting chemicals
  4. Cell to cell recognition (to avoid pathogens)
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5
Q

Is the phosphate group on a phospholipid hydrophilic or hydrophobic?

A

Hydrophilic

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6
Q

Is the fatty acid on a phospholipid hydrophilic or hydrophobic?

A

Hydrophobic

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7
Q

What is the function of the phospholipid bilayer?

A

Acts as a barrier to large polar molecules

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8
Q

What is the diagram of the plasma membrane called?

A

The fluid mosaic model

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9
Q

What is the function of the phospholipids in the plasma membrane?

A

Creates the bilayer

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10
Q

What is the function of the glycoproteins in the plasma membrane?

A

Used for cell to cell recognition

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11
Q

What is the function of the glycolipids in the plasma membrane?

A

Used for cell to cell recognition

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12
Q

What is the function of carbohydrates in the plasma membrane?

A

Used for cell to cell recognition

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13
Q

What is the function of cholesterol in the plasma membrane?

A

Makes the membrane stable and fluid

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14
Q

What is the function of extrinsic proteins in the plasma membrane?

A

Likely to be enzymes or structural material in the cytoskeleton

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15
Q

What is the function of channel forming proteins in the plasma membrane?

A

Hydrophilic pores that allows polar molecules through the membrane

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16
Q

What is the function of the phospholipid bilayer?

A

Creates a selectively permeable membrane

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17
Q

What is the function of channel proteins?

A

Allow polar molecules across the membrane

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18
Q

What is the function of carrier proteins?

A

Used in active transport and facilitated diffusion

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19
Q

What is the function of receptor proteins?

A

For hormones, a specific 3D shape complementary to molecules such as hormones

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20
Q

What are the four roles of internal membranes?

A
  1. Separate components from cytoplasm for specialisation
  2. Holds metabolic pathways in place. Chemical reactions take place on membranes
  3. Ribosomes are attached to membranes (SER)
  4. Control of movement of substances
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21
Q

Define diffusion?

A

The movement of molecules or ions from a region of high concentration to a region of low concentration down a concentration gradient

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22
Q

What type of molecules can be moved by diffusion? (2)

A

.Small non-polar molecules

.Large lipid soluble molecules

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23
Q

Does diffusion require ATP?

A

No

24
Q

Does diffusion require specific proteins?

A

No

25
Q

What are two requirements for diffusion to occur?

A
  1. A concentration gradient

2. Molecules have kinetic energy

26
Q

Give three named examples of molecules that can move by diffusion across a membrane?

A

O2, CO2, H2O

27
Q

What six factors affect the rate of diffusion?

A
  1. Temperature
  2. Concentration Gradient
  3. Surface Area
  4. Diffusion Distance
  5. Size of Molecules
  6. Lipid solubility
28
Q

How does temperature affect the rate of diffusion?

A

Increasing temperature increases kinetic energy and this the rate of diffusion

29
Q

How does concentration gradient affect the rate of diffusion?

A

Having more molecules on one side of the membrane than the other increases diffusion rate (increasing concentration gradient)

30
Q

How does surface area affect the rate of diffusion?

A

The greater the surface area, the greater the rate of diffusion

31
Q

How does diffusion distance affect the rate of diffusion?

A

The shorter the diffusion distance the greater the rate of diffusion

32
Q

How does size of the molecule affect the rate of diffusion?

A

Smaller molecules diffuse faster than larger ones. Smaller molecules have more kinetic energy

33
Q

How does lipid solubility affect the rate of diffusion?

A

Ions can only diffuse across a membrane if the specific channel for their transport is present in the membrane. The ion channels are very specific.

34
Q

Define osmosis?

A

The movement of water from an area of high water potential to an area of ow water potential, down a water potential gradient, across a selectively permeable membrane.

35
Q

What is water potential?

A

The tendency of water molecules to leave or enter a system

36
Q

What unit is water potential measure in?

A

Kilopascals (Kpa)

37
Q

What has the high water potential of 0Kpa?

A

Distilled Water

38
Q

The more negative the number the more what the water potential?

A

The lower the water potential

39
Q

What is a solvent?

A

A substance that dissolves it

40
Q

What is a solute?

A

A substance that dissolves in the solvent

41
Q

What is a hypertonic solution?

A

They have a lower water potential than the cell cytoplasm. It contains many solutes.

42
Q

What is a Isotonic solution?

A

They have the same water potential as the cell cytoplasm. It contains the same concentration of solutes.

43
Q

What is a hypotonic solution?

A

They have a higher water potential than in the cell cytoplasm. It contains more solutes.

44
Q

What is facilitated diffusion?

A

Diffusion that requires either a channel forming protein or a carrier protein

45
Q

Why do channel forming proteins allow for facilitated diffusion?

A

Channel forming proteins form hydrophilic pores to allow small polar molecules or small ons to move across the membrane.

46
Q

Why do carrier proteins allow for facilitated diffusion?

A

These have a binding site specific to a large polar molecule. They change shape (a conformational change) and deliver molecules to the other side of the membrane.

47
Q

What are the requirements for facilitated diffusion?

A
  1. Concentration Gradient
  2. Kinetic Energy
  3. No ATP
  4. Channel or Carrier protein
48
Q

Define Co-transport?

A

A type of facilitated diffusion in which two substances are simultaneously transported across a membrane by one protein complex, that does not have ATPase activity.

49
Q

Define Active transport?

A

The movement of ions and other molecules across the membrane via carrier proteins. Substances can be moved from low to high, against a concentration gradient. It requires ATP.

50
Q

What are 5 facts about active transport?

A
  1. Requires ATP
  2. Against a concentration gradient
  3. Molecules have kinetic energy
  4. Protein carriers are present
  5. If a respiratory inhibitor is present, active transport will no longer take place.
51
Q

What are two named examples of active transport use?

A
  1. Nerve impulse transmittion

2. Absorption of mineral salts by plant roots

52
Q

What is the case study example of a respiratory inhibitor?

A

Cyanide

53
Q

Define bulk transport?

A

The process by which the cell obtains solid or liquid materials that are too large to enter by diffusion or active transport.

54
Q

What are two examples of bulk transport?

A
  1. Phagocytosis - solid materials

2. Pinocytosis - liquids

55
Q

What are four facts for bulk transport?

A
  1. Membrane engulfs the material
  2. Membrane fuses together
  3. Vesicle is formed
  4. ATP required

Biology AS (14 decks)

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