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3.2 Cells (A Level Biology) > 3.2.3 Transport across Cell Membranes > Flashcards

3.2.3 Transport across Cell Membranes Flashcards

1
Q

True or false, the cell-surface membrane has the same basic structure as the membranes of organelles e.g the mitochondria/ Golgi apparatus etc

A

True

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2
Q

What are the 2 main component of the cell surface membrane

A

Phospholipid bilayer
Proteins

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3
Q

Simple diffusion is the…

A

Net movement of particles from an area of high concentration to an area of low concentration down the concentration gradient until they are evenly distributed and doesn’t require ATP

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4
Q

The type of transport where substances pass directly through the membrane is called…

A

Simple diffusion

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5
Q

For simple diffusion, the substances that are passing directly through the phospholipid bilayer must be…, …. and …

A

Small
Non charged (non polar)
Lipid-soluble

E.g oxygen, urea, carbon dioxide

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6
Q

Oxygen, carbon dioxide and urea are all small, non polar (non charged) and lipid -soluble molecules so cross the cell membrane by…

A

Passive diffusion
(The movement of substances from an area of high concentration to an area of low concentration down the concentration gradient until they are evenly spread out and doesn’t require ATP)

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7
Q

Oxygen, carbon dioxide and urea are all small, non polar (non charged) and lipid -soluble molecules so cross the cell membrane by…

A

Passive diffusion
(The movement of substances from an area of high concentration to an area of low concentration down the concentration gradient until they are evenly spread out and doesn’t require ATP)

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8
Q

True or false, ions can pass directly through the phospholipid bilayer (passive diffusion)

A

False
Because they are charged (polar) so are repelled by the hydrophobic fatty acid tails

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9
Q

Why does simple diffusion only occur in liquids and gases

A

The substances must have kinetic energy to be able to move so that they can cross the cell membrane
(So even though simple diffusion doesn’t require external energy in the form if ATP, the substances still require energy)

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10
Q

Facilitated diffusion is…

A

the movement of substances across the membrane using channel proteins and carrier proteins. The substances move from an area of higher concentration to an area of lower concentration down the concentration gradient until they are evenly spread out and no ATP is required.

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11
Q

Facilitated diffusion is how,..and…cross the membrane

A

Large particles
Charged particles

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12
Q

Both simple diffusion and facilitated diffusion are ..processes meaning no external energy is required in the form of ATP.
However the substances will have kinetic energy to allow them to move

A

Passive

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13
Q

In facilitated diffusion the 2 types of transport proteins used are…and…proteins

A

Carrier
Channel

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14
Q

2 similarities between simple diffusion and facilitated diffusion

A

Both are passive processes (don’t require any external energy in the form of ATP, only kinetic energy which the substances already have)
Both are the movement of substances down a concentration gradient

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15
Q

2 differences between simple diffusion and facilitated diffusion

A

Simple diffusion is for small, non polar (non-charged) and lipid soluble substances e.g carbon dioxide, oxygen and urea
Facilitated diffusion is for large and charged particles

For simple diffusion the substances cross directly through the phospholipid bilayer
For facilitated diffusion the substances cross the phospholipid bilayer using transport proteins (channel/ carrier) so don’t pass directly through

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16
Q

Out of channel proteins and carrier proteins, which requires ATP from hydrolysis

A

Carrier
(Energy is needed to close the protein once the substance has entered and then to release the substance on the other side of the membrane)

Channel proteins don’t require energy in the form of ATP as they don’t need to move as they have a continuous pore/ column so are always open

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17
Q

Carrier proteins require energy in the form of ATP in order to transport the substance across the membrane. How will they get this energy

A

For active transport, ATP will bind to the protein and be hydrolysed into ADP and Pi
This process of hydrolysis breaks a bond between 2 phosphate groups which releases energy

(Don’t know about for facilitated diffusion as whilst carrier proteins are used, we don’t say that facilitated disguise requires any energy in the form of ATP)

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18
Q

Channel proteins vs carrier proteins (both are used in facilitated diffusion to transport large and charged substances across the membrane)

A

Channel proteins are a continuous column/ pore and are always open so don’t require any energy in the form of ATP (they don’t need to move or do anything)

Carrier proteins require energy in the form of ATP by ATP hydrolysis in order to be able to move (to close once the substance has entered the protein and then to release the substance on the other side of the membrane)

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19
Q

True or false, because carrier proteins require energy in the form of ATP and they’re used in facilitated diffusion, we say that facilitated diffusion requires energy in the form of ATP

A

False
All types of diffusion are described as passive processes (no external energy required in the form of ATP)
Even though carrier proteins require ATP, channel proteins don’t and channel proteins are the main protein used in facilitated diffusion

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20
Q

Process of carrier protein allowing substance to pass through membrane

A

The substance binds to carrier protein which causes the protein to change shape so that the substance can be released on the other side of the membrane

(The carrier protein will always be open at one side of the membrane
The substance enters the protein where it’s open
The protein then closes to ‘enclose’ the substance in it
The substance is released on the other side of the protein to where it entered)

(This process requires energy in the form of ATP to allow the protein to move to let the substance pass through)

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21
Q

The main substance that passes through channel proteins is…

A

Ions
(As they are small and charged- remember they can’t pass directly through the phospholipid bilayer via passive diffusion as even though they’re small, they’re charged so will be repelled by the hydrophobic fatty acid tails)

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22
Q

If a charged particle tries to pass directly through the phospholipid bilayer via passive diffusion, it will be…by the hydrophobic fatty acid tails

A

Repelled

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23
Q

If a charged particle tries to pass directly through the phospholipid bilayer via passive diffusion, it will be…by the hydrophobic fatty acid tails

A

Repelled

24
Q

The main substances that cross the membrane via carrier proteins is…and…substances

A

Larger
Charged (polar)

E.g glucose and amino acids

25
Q

Carrier proteins are a continuous column/ pore filled with…which allows polar substances to pass through

A

Water
(As polar/ charged substances are water-soluble))

26
Q

When a substance binds to a carrier protein, it causes the protein to change…so that the substance can be released on the other side of the membrane

A

Shape

27
Q

Osmosis is …

A

The net movement of water from an area of high water potential to an area of low water potential down a water potential gradient and through a selectively permeable membrane until the water molecules are evenly spread out. The process is passive and doesn’t require energy in the form of ATP

28
Q

Water potential is the…created by water molecules and is measured in…

A

Pressure
kPa (KiloPascals)

29
Q

The highest value you can get for water potential is …where the water has no solute dissolved in it (it’s pure water)

A

0
(As soon as you add any solute to the water then the water potential becomes negative)

30
Q

If the water potential is 0 it means that…

A

It’s pure water (there’s no solute dissolved in it)

31
Q

The more negative the water potential is, the more…there is that’s dissolved in it

A

Solute

32
Q

If cells are placed in an isotonic solution it means that…

A

The water potential inside the cells and inside the solution is the same so there will be no net movement of water in or out of the cells by osmosis

33
Q

If cells are placed in an isotonic solution why is there no net movement of water in or out of the cell

A

The water potential inside the cells is the same as the water potential of the solution so there’s no water potential gradient

34
Q

If cells are placed in an isotonic solution why is there no net movement of water in or out of the cell

A

The water potential inside the cells is the same as the water potential of the solution so there’s no water potential gradient

35
Q

What does it mean if cells are placed in a hypotonic solution

A

The solution has a lower solute concentration than the cells so a higher water potential than the cells
So water will move into the cells from the solution via osmosis

36
Q

A hypotonic solution has a low…concentration and a higher…

A

Solute
Water potential

37
Q

A hypertonic solution has a high…concentration and a lower…

A

Solute
Water potential

38
Q

What does it mean if cells are placed in a hypertonic solution

A

The solute concentration is higher outside of the cell than inside the cell
So the solution has a lower water potential than inside the cell
So water moves out of the cell into the solution via osmosis

39
Q

Will water by osmosis from a more negative water potential to a less negative water potential or the other way around

A

The other way around
Water will be move from a less negative water potential to a more negative water potential
(As a less negative water potential is higher so means that the water is purer and has a lower solute concentration)

40
Q

What happens when an animal cell is placed in a hypotonic solution (the solution has a higher water potential than the cell)

A

Water will eneter the cell via osmosis
The cell could burst (lysis)

41
Q

If an animal cell is placed in a hypotonic solution, water will move into the cell by osmosis which may cause the cell to burst (…)

A

Lysis

42
Q

What happens when a plant cell is placed in a hypotonic solution (the solution has a higher water potential than the cell)

A

Water will enter the cell by osmosis and the cell will become turgid
(The cytoplasm and vacuole increase in size)

43
Q

When water enters a plant cell (e.g when the plant cell is placed in a hypotonic solution), the …and…will increase in size making the cell turgid

A

Cytoplasm
Vacuole

44
Q

What happens to animal cells vs plant cells when placed in a hypotonic solution

A

Animal cell= water enters cell by osmosis which may cause the cell to burst
Plant cell= water enters the cell by osmosis which make the cell turgid (and the cytoplasm and vacuole increase in size)

(Plant cells don’t burst because of the cell wall which strengthens the cell)

45
Q

What happens when an animal cell is placed in a hypertonic solution (the water potential is higher inside the cell than in the solution)

A

Water leaves the cell by osmosis
The cell will become shrivelled

46
Q

What happens when a plant cell is placed in a hypertonic solution (the water potential is higher inside the cell than in the solution)

A

Water leaves the cell by osmosis
The cell becomes flaccid/ plasmolysed (the cytoplasm and vacuole decrease in size)

47
Q

What happens when animal cells vs plant cells are placed in a hypertonic solution (water potential is higher inside the cell than in the solution)

A

Animal cell= water leaves the cell by osmosis, the cell becomes shrivelled
Plant cell= water leaves the cell by osmosis, the cell becomes flaccid/ plasmolysed (the cytoplasm and vacuole decrease in size)

48
Q

True or false, the same thing happens to plant cells and animal cells when they’re placed in hypertonic/ hypotonic solutions

A

False (as plant cells have a cell wall which strengthens the cell)
E.g when animal cells are placed in a hypotonic solution they burst but plant cells just become turgid (the cytoplasm and vacuole increase in size)
E.g When animal cells are placed in a hypertonic solution they become shrivelled but plant cells become flaccid/ plasmolysed (the cytoplasm and vacuole decrease in size)

49
Q

When cells are placed in a hypotonic solution, water…the cell by osmosis

A

Enters

50
Q

When cells are placed in a hypertonic solution, water…the cell by osmosis

A

Leaves

51
Q

Active transport is…

A

The movement of substances from an area of low concentration to an area of high concentration against the concentration gradient and requires carrier proteins and energy in the form of ATP

52
Q

Facilitated diffusion uses both channel and carrier proteins but active transport only uses…proteins

A

Carrier

53
Q

In active transport the carrier proteins act as…to move the substance across the membrane

A

Pumps

54
Q

For a substance to move across the membrane via carrier proteins, it must be …in shape to the protein to be able to bind to it

A

Complementary
(This occurs for both facilitated diffusion and active transport as they both use carrier proteins)

55
Q

For a substance to move across the membrane via carrier proteins, it must be …in shape to the protein to be able to bind to it

A

Complementary
(This occurs for both facilitated diffusion and active transport as they both use carrier proteins)

3.2 Cells (A Level Biology) (5 decks)

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