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BIOLOGY > CELL MEMBRANES AND TRANSPORT > Flashcards

CELL MEMBRANES AND TRANSPORT Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Cell membranes

A

Controls what enters and leave the cell . Partially permeable . Made of proteins and phospholipids

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2
Q

Phospholipids properties in a cell membrane

A

-can form bilayers with one sheet of phospholipids
- have hydrophilic heads and hydrophobic tails
-allows lipid soluble molecules across but not water soluble molecules

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3
Q

Proteins are embedded through

A

The phospholipid bilayer they are embedded in two different ways . Extrinsic and intrinsic proteins.

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4
Q

Extrinsic proteins

A

-on the surface of the bilayer
-provide structural support and form recognition sites by identifying cells and receptor sites

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5
Q

Intrinsic proteins

A

-include transport proteins which use active or passive transport to move molecules and ions across cell membranes
-for example channel and carrier. Proteins

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6
Q

Fluid mosaic model

A

Model of the structure of biological membranes in which proteins are studded through a phospholipid bilayer

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7
Q

Cholesterol is

A

A mostly hydrophobic molecule that regulates membrane fluidity . And in animal cells sits between the phospholipid molecules making membrane stable at high temperatures

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8
Q

Why is it called the fluid mosaic model of membrane structure

A

Fluid- individual phospholipid molecules can move within a layer with one another
-mosaic-the proteins embedded in the bilayer vary in shape and size and in their distribution (mosaic)

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9
Q

Plant and animal cell membranes contain ………….

A

Glycoproteins ,glycolipids and sterols

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10
Q

The permeability of a membrane differs due to

A

-ethanol
-heat
-Ph

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11
Q

Water soluble substances cannot

A

Diffuse readily , they pas through intrinsic protein

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12
Q

Diffusion

A

The passive movement of a molecule or ion down a concentration gradient from a region of higher concentration and lower concentration .

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13
Q

Passive

A

Not requiring energy provided by the cell

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14
Q

If ions and molecules are highly concentrated in

A

One area there will be a total movement away from that area

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15
Q

Rate of diffusion is affected by

A

1.the concentration gradient -the greater the difference in concentration more molecules diffuse in a given time
2.the thickness of the exchange surface/distance of travel
3.the surface area o the membrane the larger the area the more molecules diffuse

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16
Q

Rate of diffusion equation

A

Surface area x difference in concentration ➗length of the diffusion path

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17
Q

Some other factors that can affect the rate of diffusion ;

A

1.the size of the diffusing molecule
2.the nature of the diffusing molecules
3. The temperature

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18
Q

The rate of oxygen uptake increases the

A

Concentration gradient

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19
Q

Facilitated diffusion

A

The passive transport of molecules or ions down a concentration gradient across a Chanel or a carrier protein

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20
Q

Molecules such as glucose cannot pas though cell membrane because

A

They are insoluble in the phospholipid bilayer

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21
Q

Water soluble molecules are

A

Repelled by the hydrophobic tails

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22
Q

Channel proteins are proteins with

A

Pores lied with polar groups . The channels are hydrophobic water soluble ions can pass .

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23
Q

channel proteins open and

A

Close acccording to the needs of the cells

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24
Q

Carrier proteins allow

A

Diffusion of larger polar molecules .

25
Q

The carrier proteins attaches

A

To the binding site and the carrier protein changes shape and releases the molecule . It then changes back to its own shape

26
Q

Channel proteins contain ;

A
  • a pore
    -allow diffusion and facilitated diffusion
    -allows for rapid transport
27
Q

Carrier proteins contain ; (3)

A

-contain no pores
-allow diffusion. Facilitated diffusion and active transport
-sower transport 10 to the power of 4 ions

28
Q

Active transport

A

The movement of molecules or ions across a membrane against a concentration gradient using the energy from the hydrolysis of ATP .

29
Q

Features of active transport

A

-ions and molecules moved from lower to a higher concentration
-the process requires energy from ATP
-anything affecting respiration will affect active transport
-occurs through intrinsic carrier protein
-rate of active transport determined by the availability of carrier proteins

30
Q

Examples of active transport in humans

A
  • muscle contraction
    -nerve impulse transmission
    -mineral uptake in root hair cells
31
Q

Step to active transport

A
  1. Molecule combines with carrier protein on the osteitis of cell
  2. ATP transfers a phosphate group to he carrier protein
  3. Carrier protein changes shape and carries the molecule
  4. Molecule into cytoplasm
  5. Phosphate ion releases back and recombines with ADP an ATP
  6. Carrier protein returns to its original shape
32
Q

Cells performing Active transport

A

Are packed with mitochondria. As mitochondria provides energy from ATP

33
Q

The rate of uptake is reduced with

A

A respiratory inhibitor such as cyanide

34
Q

The higher the rate of

A

Respiration the higher the rate of active transport

35
Q

Co-transport

A

One type of facilitated diffusion that brings molecules and ions into cells together on the same transport protein

36
Q

Sodium glucose co-transport is significant in

A

Absorbing glucose and sodium ions across cell membranes into the blood in the ileum

37
Q

Osmosis

A

The net passive movement of water molecules across a partially permeable membrane from a region of higher water potential to a region of lower water potential . .

38
Q

Water potential

A

The tendency of water to move into a system .

39
Q

Water potential is decreased by

A

The addition of a solute

40
Q

Pure water has a water potential

A

Of zero 0 which is the highest value of water

41
Q

Solute potential

A

Is the magnitude for the solute to to decrease In water potential

42
Q

Solute potential measures

A

How easily for water molecules to move out of a solution

43
Q

Higher water potential =

A

Lower solute potential

44
Q

Water potential =

A

Pressure potential + solute potential

45
Q

Turgid

A

A plant cell that holds as much water as possible . Further entry of water is prevented s th cel wall cannot expand further

46
Q

Glycocalyx

A

A glycoproteins and glycolipid coating supporting the cell membrane of some cells

47
Q

How does temperature affect the permeability of the plasma membrane

A

As temperature increases the phospholipids make more kinetic energy and move more increasing the fluidity and permeability

48
Q

Isotonic

A

If the water potential is equal o that of the external and internal solution . “1m and 1m”. No net water movement

49
Q

Hypertonic

A

Is the water potential of the cell is lower than the water potential outside the cell. Cell starts to lose water TURGOR pressure decreases . Shrinks

50
Q

Hypotonic

A

If the water potential of the cell is higher than that of the external solution . Water will start to move into the cell . Exerts Turgor pressure and swells up .

51
Q

Plasmolysis

A

The drawing in of the cytoplasm and the cell membrane from the cell wall as it loses water by osmosis . TEARED UP

52
Q

Incipient plasmolysis

A

Cell membrane and cytoplasm are attached from the cell wall due to lack of water to make the cell turgid .

53
Q

Endocytosis

A

The bulk uptake of substances into a cell by invagination of the membrane to form a vesicle with the usage if energy from ATP

54
Q

Th two types of Endocytosis

A
  1. Phagocytosis
  2. Pinocytosis
55
Q

Phagocytosis

A

The engulfing of solid material such as pathogens via a vesicle

56
Q

Pinocytosis

A

The engulfing of fluids into the cell via a vesicle

57
Q

Exocytosis

A

The [process where substances may leave the cell via a vesicle using energy from AT P

58
Q

When bulk transport occurs

A

The cell membrane has to change shape requiring energy from ATP

BIOLOGY (8 decks)

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