Topic 3- Transport And Cell Membranes Flashcards

1
Q

How does the plasma membrane appear under a light microscope

A

As a double line

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2
Q

What are the two types of protein found in the plasma membrane

A

Intrinsic and extrinsic proteins

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3
Q

What are intrinsic proteins involved in

A

Transporting substances across the cell membrane

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4
Q

What are extrinsic proteins involved so

A

Act as receptors as they have a specific binding site, and are involved in cell to cell signalling and cell to cell recognition

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5
Q

What is the main function of the plasma membrane

A

Cell to cell recognition and cell to cell signalling

As well as controlling what substances enter and exit the cell

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6
Q

What is diffusion.

A

The movement of molecules from and area of high concentration to an area of low concentration down a concentration gradient

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7
Q

What molecules use simple diffusion

A

Lipid soluble molecules which are non polar and uncharged

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8
Q

Name substances that carry out simple lipid diffusion

A

Lipid soluble steroids
Oxygen
Carbon dioxide

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9
Q

What is facilitated diffusion

A

Passive transport of substances across a plasma membrane with the help of an intrinsic protein either through a carrier protein or a hydrophilic pore within a protein channel

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10
Q

What substances use facilitated diffusion

A

Large water soluble polar and charged molecules or ions

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11
Q

What are the two kinds of transport proteins

A

Channel proteins and Cartier proteins

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12
Q

What is active transport

A

An active process which moves against a concentration gradient from low to high concentration requiring an input of ATP energy

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13
Q

Name some examples of active transport

A

Transport of mineral ions in the root hair cells of plants

Glucose from kidney to the blood

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14
Q

How can active transport be stopped

A

By adding a metabolic poison called cyanide which stops the atp energy being produced, without atp active transport can not occur

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15
Q

How does phospholipids arrange themselves in water

A

As a Micelle, with the hydrophilic head facing outwards and the hydrophobic tails facing inwards

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16
Q

Why is structure of the plasma membrane described as a fluid mosaic structure

A

Fluid because all the parts move relative to each other and mosaic because all proteins are dotted through out the membrane like tiles

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17
Q

Describe the structure of the plasma membrane

A

Demi phospholipid bilayer composed of intrinsic and extrinsic proteins, glycolipids, glycoproteins and cholesterol arranged in a fluid mosaic structure

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18
Q

Who proposed the fluid mosaic structure of the plasma membrane

A

Singer and Nicholson

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19
Q

How are phospholipids arranged in water

A

As a Michelle with the hydrophilic heads outside and the hydrophobic heads facing in side

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20
Q

What are the main functions of the plasma membrane

A

Provide the cells structure, cell to cell signalling and cell to cell recognition

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21
Q

What does lipid bilayer mean

A

Two layers of phospholipid

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22
Q

What is a phospholipid

A

A molecule made of a hydrophilic glycerol phosphate head and two fatty acids forming a hydrophobic tail

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23
Q

What is the distance across the membrane

A

7-8 nm

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24
Q

How does an intrinsic protein differ from an extrinsic protein

A

Intrinsic proteins lie across both layers of the bilayer. Extrinsic proteins are in one of the layers on the surface of the membrane

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25
What are intrinsic proteins
Proteins that lie across both the layers of the membrane
26
What are extrinsic proteins
Lay in one layer of the membrane or on the surface of the membrane.
27
What are glycoproteins
Proteins with a carbohydrate chain attached
28
What are glycolipids
Lipids with a carbohydrate chain attached
29
What are glycolipids involved with
Cell to cell recognition
30
What are glycoproteins involved with
Cell to cell recognition
31
What is the structure of the plasma membrane
A semi fluid phospholipid bilayer containing intrinsic and extrinsic proteins, glycoproteins and glycolipids and cholesterol
32
Why is the plasma membrane selectively permeable
It is able to control what substances enter and exit the cell
33
What is the role of cholesterol in the plasma membrane
Increase its rigidity
34
Name the model proposed by singer and Nicholson
Fluid mosaic model
35
What factors increase the rate of diffusion
Increasing temperature Decreasing size Increasing solubility in lipids Increasing concentration
36
What is facilitated diffusion
A form of diffusion where the molecules move from an area of high concentration to an area of low concentration down a concentration gradient via a carrier protein or a hydrophilic pre within A channel protein
37
Does diffusion require ATP
No
38
What are the two kinds of transport proteins
Carrier protein and a channel protein
39
Draw a diagram to show diffusion
Draw
40
Draw a picture to show facilitated diffusion
Draw
41
Why is the partially permeable membrane important in osmosis
It ensures that large solutes do not diffuse and counteract the effect of osmosis
42
What is osmosis
The movement of water molecules from a high water potential to a low water potential across a partially permeable membrane
43
What is the equation that allows you to work out the water potential
¥cell = ¥s +¥p
44
What is the water potential of pure water
0kpa
45
Describe the relationship between the water potential the pressure potential and the solute potential
The water potential is equal to the solute potential plus the pressure potential
46
Is the highest possible water potential and what has this
Water and 0kpa
47
What is the solute potential generated by
The solutes dissolved in the water
48
What is the pressure potential generated by
THe cytoplasm pushing on the cell wall. As the cell wall is rigid it persists the pressure
49
During osmosis what is the solution with the highest water potential known as
Hypotonic solution
50
During osmosis what is the solution with the lower water potential called
Hypertonic
51
What is the word that describes when bin solutions have the same water potential
Isotonic
52
What happens when the solutions are isotonic
Both the solutions have the same water potential so there is no not movement
53
What happens when a plant cell is placed in a hypertonic solution
The solution will loose water and become flaccid and plasmolysed
54
What does plasmolysis mean
Where the cytoplasm shrinks and comes away from the cell wall causing the plant to wilt
55
What happens when plant cells are placed on a hypotonic solution
They will gain water, swell and become turgid
56
Why is it important that the cells become turgid
It ensures the plant will remain upright
57
What happens to plant cells that are placed in a hypertonic solution
Loose water and become shrivelled
58
What happens to animal cells when they are placed in a hypotonic solution
They will gain water swell and then burst
59
What is incipient plasmolysis
The point at which the cytoplasm behind to come away from the cell wall
60
How can incipient plasmolysis be found experimentally
Observing the solute potential at which half the plant cells in a sample are plasmolysis . At this point the solute potential is equal to the water potential - this is due to the pressure potential being zero as the cytoplasm is no knee pushing against the cell wall
61
Draw a plant cell in a hypotonic isotonic and hypertonic solution
Draw and check text book
62
Draw a plant cell in a hypotonic hypertonic and isotonic solution
Draw and check text book