Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology Module 2 > 5. Plasma Membrane > Flashcards

5. Plasma Membrane Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Functions of membrane (role of membrane in cells = 18ii)

A

Compartmentalisation
• Site for attachment of enzymes
• Provide selective permeability
• Create concentration gradients
Site of chemical reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why can glucose not pass through a cell membrane through simple diffusion

A

Glucose molecules too large
Phospholipids act as a barrier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Function of cholesterol in plasma membrane

A

Regulates fluidity = sits between tails
Increases strength and stability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Role of membrane in RER (19)

A
  • compartmentalisation
  • separating proteins from cell cytoplasm
  • hold ribosomes in place
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Compartmentalisation

A

creating organelles within a cell e.g. Mitochondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What organelles have membranes

A

Lysosomes
Golgi body
ER
Mitochondria
Chloroplast
Vacuole
Nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Organelles without membrane

A

Centrioles
Ribosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Model of membrane name

A

Fluid mosaic model

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why is the model called fluid

A

o The phospholipids and proteins can move around via diffusion
o The phospholipids mainly move sideways, within their own layers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Main components in the fluid mosaic model

A

o Phospholipids o Cholesterol
o Glycoproteins and glycolipids
o Transport proteins - carrier + Channel proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What’s the cell surface membrane also known as

A

Phospholipid bilayer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How are phospholipids arranged in the cell surface membrane

A

tails form a hydrophobic core comprising the innermost part of both the outer and inner layer of the membrane
Heads face outwards - hydrophilic sides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does the cell surface membrane act as a barrier to

A

most water-soluble substances (due to hydrophobic tails)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does having a membrane that acts as a barrier most water-soluble substances ensure

A

ensures water-soluble molecules such as sugars, amino acids and proteins cannot leak out of the cell and unwanted water-soluble molecules cannot get in

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Can water go through the membrane

A

Yes kind of

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why can water go through the membrane

A

Water - very small molecule - can still slowly squeeze its way through, despite being hydrophobic core

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is a micelle

A

Phospholipids arranged in a spherical form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why do micelles form

A

not enough phospholipids to form a full bilayer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Two types of phospholipids

A

Saturated and unsaturated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the difference between saturated and unsaturated phospholipids

A

saturated fatty acids - straight tails
• unsaturated fatty acids = double bond = - tails with kinks/bends in them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What increases the fluidity of the membrane

A

Increasing the number of unsaturated fatty acids / phospholipids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Why does increasing the number of unsaturated fatty acids increase the fluidity of the membrane

A

more unsaturated fatty acids = more distance between the tails and thus
fewer intermolecular interactions = more fluidity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How does cholesterol stop the membrane from becoming to fluid at high temps

A

Cholesterol molecules bind to the hydrophobic tails of phospholipids, stabilising them and causing phospholipids to pack more closely together= decreasing fluidity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Extrinsic proteins

A

proteins which are found on the surface of the plasma membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

General function of extrinsic proteins

A

usually function as enzymes and catalyse chemical reactions inside the cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what are Intrinsic proteins

A

proteins which span both bilayers of the plasma membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

General function of intrinsic proteins

A

act as channels or carrier proteins to transport water-soluble molecules.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are glycoproteins

A

Proteins Embedded in the cell-surface membrane with attached carbohydrate (sugar) chains of varying lengths and shapes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Function of glycoproteins

A

Cell Signalling
Recognition sites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Example of cell signalling

A

Receptors for peptide hormones, inc. insulin and glucagon, which affect the uptake/storage of glucose by cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What type of proteins are glycoproteins

A

Intrinsic proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What are glycolipids

A

lipids with attached carbohydrate (sugar) chains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Function of glycolipids

A

Recognition sites / antigens
can be recognised by cells of immune system as self (of the organism) or non-self (belongs to another organism).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are extrinsic proteins also known as

A

Peripheral protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Function of transport proteins

A

create hydrophilic channels to allow ions and polar molecules to travel through the membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Types of transport proteins

A

Channel protein
Carrier protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Function of channel proteins

A

Transport polar substances down a concentration gradient
allow the cell to control which substances enter or leave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Function of carrier proteins

A

Transport molecules against the concentration gradient
allow the cell to control which substances enter or leave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Adaption of carrier proteins

A

change shape to transport a substance across the membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Can any molecule go down any channel / carrier protein

A

No = • Each transport protein is specific to a particular ion or molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What two factors effect membrane permeability

A

Temp + solvent concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Initial effect of increase temp on membrane permeability

A

• Phospholipids in a cell membrane are constantly moving.
• When temp. increased, the phospholipids have more kinetic energy = move more.
• This makes a membrane more fluid, and it will start to lose structure =
REVERSIBLE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Later effect of increased temp on membrane permeability

A

Temp. continues to increase = cell will break down completely.
• Loss of structure increases permeability of membrane, making it easier for particles to cross it.
• Carrier and channel proteins in membrane will be denatured at high temps.
These proteins -> involved in transport across membrane = so as they denature
= membrane permeability is affected. = IRREVERSIBILE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What also takes place at increased temps across a membrane

A

• Any diffusion taking place through the cell membrane will also occur at a higher speed (due to increased kinetic energy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

How does solvent concentration effect membrane permeability

A

Organic solvents can increase cell membrane permeability as they dissolve the lipids in the membrane, causing the membrane to lose its structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Define diffusion

A

the net passive movement of molecules from an area of high concentration to an area of low concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What happens after a long period of diffusion

A

Reaches equilibrium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

How does temp effect rate of diffusion

A

Molecules and ions have more kinetic energy at higher temperatures
• They move faster, resulting in a higher rate of diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

How’s does the concentration gradient effect rate of diffusion

A

o This is the difference in the concentration of the
substance on the two sides of the surface o If there are more molecules on one side of a membrane than on the other, at any one moment more molecules will randomly move across the membrane from that side than from the other
• A greater difference in concentration means a greater difference in the number of molecules passing in the two directions and therefore a faster rate of diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

How does SA effect the rate of diffusion

A

The greater the surface area across which diffusion is taking place, the greater the number of molecules or ions that can cross it at any one moment and therefore the faster diffusion occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

How can you increase the SA of an organelle / organism

A

Or decreasing it’s size
• The surface area of cell membranes can be increased by folding (eg. microvilli in the intestine or cristae in mitochondria)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

How does the properties of the molecules or ions dissolving effect the rate of diffusion

A

• Large molecules diffuse more slowly than smaller ones as they require more energy to move
• Uncharged and non-polar molecules diffuse directly across the phospholipid bilayer
• Non-polar molecules diffuse more quickly than polar ones as they are soluble in the non -polar phospholipid bilayer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

how do decrease the fluidity of a membrane

A

An increased proportion of saturated fatty acid chains as the chains pack together tightly and therefore there is a high number of intermolecular forces between the chains
• A lower temperature as the molecules have less energy and therefore are not moving as freely which causes the structure to be more closely packed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

how to increase the fluidity of a membrane

A

• An increased proportion of unsaturated fatty acid chains as these chains are bent, which means the chains are less tightly packed together and there are less intermolecular forces
• At higher temperatures, the molecules have more energy and therefore move more freely, which increasing membrane fluidity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What can no diffuse through phospholipid bilayer

A

o Large polar molecules such as glucose and amino acids o lons such as sodium ions (Nat) and chloride ions (CI-)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What is facilitated diffusion

A

When certain molecules require transport proteins to diffuse across a membrane

57
Q

What two types of molecules enable facilitated diffusion

A

Channel proteins
Carrier proteins

58
Q

Properties of transport proteins

A

Highly specific

59
Q

What are channel proteins

A

Water filled pores

60
Q

What do channel proteins allow

A

charged substances (eg. ions) to diffuse through the cell membrane = down conc
Gradient

61
Q

Most channel proteins are…

A

Gated

62
Q

What does gated mean

A

that part of the channel protein on the inside surface of the membrane can move in order to close or open the pore
• This allows the channel protein to control the exchange of ions

63
Q

How do carrier proteins function in facilitated diffusion

A

the binding site of the carrier protein to be open to one side of the membrane first, and then open to the other side of the membrane when the carrier protein switches shape

64
Q

Define active transport

A

net movement of molecules against the concentration gradient, across a cell membrane, using ATP

65
Q

What does active transport require

A

ATP + carrier proteins

66
Q

Carrier proteins can change shape. Can it change shape in facilitated diffusion + why

A

No - requires energy for it to change shape = ONLY CHANGES SHAPE IN ACTIVE
TRANSPORT

67
Q

In facilitated diffusion molecules move

A

Down a conc gradient

68
Q

How does atp release energy

A

It is hydrolysed

69
Q

Importance of active transport

A

The reabsorption of useful molecules and ions into the blood after filtration into the kidney tubules
• The absorption of some products of digestion from the digestive tract
• The loading of sugar from the photosynthesising cells of leaves into the phloem tissue for transport around the plant
• The loading of inorganic ions from the soil into root hairs

70
Q

What is diffusion / osmosis / active transport responsible for

A

the transport of individual molecules or ions across cell membranes

71
Q

Exocytosis

A

bulk transport in which the vesicle containing the product fuses with the plasma membrane, allowing the content to be released out.

72
Q

Endocytosis

A

bulk transport in which a vesicle fuses with the plasma membrane, allowing substances to be released inside.

73
Q

For Endocytosis and Exocytosis need…

A

ATP = vesicles need it to move around

74
Q

Example of bulk transport materials that need to cross the membrane

A

o Large molecules such as proteins or polysaccharides o Parts of cells o Whole cells e.g. Bacteria

75
Q

If both exocytosis and endocytosis require energy, what does that make them

A

Forms of active transport

76
Q

Two forms of endocytosis

A

Phagocytosis
Pinocytosis

77
Q

What is phagocytosis

A

bulk intake of solid material by a cell

78
Q

Cells that specialise in phagocytosis are called.

A

Phagocytes

79
Q

The vacuoles formed in phagocytosis are called

A

phagocytic vacuoles

80
Q

Example of phagocytosis

A

engulfing of bacteria by phagocytic white blood cells

81
Q

What is pinocytosis

A

bulk intake of liquids

82
Q

How’ does Exocytosis work

A

• The substances to be released (such as enzymes, hormones or cell wall building materials) are packaged into secretory vesicles formed from the Golgi body
• These vesicles then travel to the cell surface membrane
• Here they fuse with the cell membrane and release their contents outside of the cell

83
Q

Example of Exocytosis

A

secretion of digestive enzymes from pancreatic cells

84
Q

Which processes require energy

A

ALL EXOCTYOSIS + ENDOCYTOSIS + ACTIVE
TRANSPORT REQUIRE ENERGY

85
Q

Define osmosis

A

Net movement of water molecules from an area of high water potential, to an area of lower water potential, across a partially permeable membrane

86
Q

Water potential of pure water

A

O kPa (at standard temp. and at pressure, -25 degrees C and 100kPa)

87
Q

Symbol of water potential

A
88
Q

All solutions have … water potentials

A

Negative

89
Q

If the concentration of a solution increases, what happens to the numerical value of the water potential

A

more concentrated the solution, the more negative the water potential

90
Q

What happens if an animal cell is placed in a hypertonic solution

A

cell water will leave the cell through its partially permeable cell surface membrane by osmosis and the cell will shrink and shrivel up
• Crenation = fatal

91
Q

What happens if an animal cell is places in a hypotonic solution

A

water will enter the cell through its partially permeable cell surface membrane by osmosis
• Cell will gain water until cell membrane is stretched too far
• Lysis = bursts = hypotonic

92
Q

What happens if a plant cell is placed in a hypertonic solution

A

water will leave the plant cell through its partially permeable cell surface membrane by osmosis
• As water leaves the vacuole of the plant cell, the volume of the plant cell decreases
• The protoplast gradually shrinks and no longer exerts pressure on the cell wall and begins to pull away from the cell wall
• the plant cell is plasmolysed

93
Q

What happens if a plant cell is placed into a hypotonic solution

A

water will enter the plant cell through its partially permeable cell surface membrane by osmosis
• As water enters the vacuole of the plant cell, the volume of the plant cell increases
• The expanding protoplast pushes against the cell wall and pressure builds up inside the cell - the inelastic cell wall prevents the cell from bursting
• The pressure created by the cell wall also stops too much water from entering and this also helps to prevent the cell from bursting
• When a plant cell is fully inflated with water and has become rigid and firm, it is described as fully turgid

94
Q

What is the protoplast

A

(living part of the cell inside the cell wall = everything except the cell wall

95
Q

Why is turgidity important in plant cells

A

Provides support and strength to plants

96
Q

Co transport

A

When there is no concentration gradient of an ion, we create one ourself. If you pump the sodium ions out there’s more outside than inside = sodium ion concentration gradient. Sodium will want to move back in. It comes back through facilitated diffusion because it’s an ion. In doing so, it’ll bring glucose with it. Pumping of the ions against the concentration gradient = active transport = used to push the ions out to create a gradient.

97
Q

Hypertonic

A

any external solution that has a high solute concentration and low water concentration compared to body fluids

98
Q

Hypotonic

A

when the solute concentration is lower than the concentration inside the cell.

99
Q

Isotonic

A

any external solution that has the same solute concentration and water concentration compared to body fluids.

100
Q

Effect of low temperature on phospholipid bilayer

A

he phospholipid molecules in the membrane are packed closely together and are less mobile, making the membrane more rigid and less permeable.

101
Q

Effect of incredibly low temperatures on permeability

A

When temperatures fall low enough for ice crystals to form, these can puncture the membrane which increases its permeability when the cell membrane rethaws, damaging the cell.

102
Q

Effect of incredibly high temperature on membrane permeability

A

permeability increases rapidly because proteins in the membrane become denatured and start to unravel

103
Q

Effect of ethanol on permeability

A

Ethanol is non polar solvent so it dissolves non polar substances such as lipids
- if you place a cell in ethanol, its membrane will become permeable and allow substances to leak into and out of the cell.

As the ethanol concentration increases, membrane permeability will increase.

104
Q

Testing effect of temperature change in membrane permeability practical

A

Prepare eight cylinders of beetroot of equal size. Make these samples as similar as possible, e.g. by cutting from the same part of each plant. Rinse each piece to remove any pigment released during cutting.
If you are investigating the effect of temperature, prepare eight water baths of varying temperatures ranging from 0-70oC.
Prepare a series of test tubes containing the same volume of water (e.g. 10 cm3). Place the tubes in different water for five minutes.
Place a single sample of beetroot into each of the eight test tubes. Leave for 15 minutes.
Use forceps to remove the pieces of beetroot from each tube. Keep the coloured liquid and transfer into a cuvette.
Use a colorimeter to measure how much light is absorbed by each liquid. The darker the solution (i.e. the more permeable the membrane), the more light is absorbed.
Draw a graph plotting absorbance against temperature.

105
Q

General pattern of effect of temperature change in membrane permeability practical

A

as temperature increases, membrane permeability also increases

106
Q

Limitations of beetroot practical

A
  • beetroot pieces may not be identical size and shape
  • some part of beetroot tissue have more pigment than others
  • excess pigment may not have been washed off the beetroot properly
107
Q

How are plants strong and supported

A
  • water enters vacuole
  • pressure against cell wall
  • turgor pressure
  • turgid cells support plant
108
Q

What is cell signalling

A

communication between cells;
- molecule released by one cell causes change in another cell;

109
Q
A

B = larger SA:V = faster diffusion

110
Q
A
111
Q

What two substances are required to break the glycosidic bond in lactose?

A

Water and enzyme

112
Q
A
113
Q

Suggest and explain why a low pH might cause the red pigment to leak out of the beetroot cells.

A
114
Q

Outline how the students could modify their investigation to get a more accurate value for the pH at which the red pigment begins to leak out of the beetroot cells.

A
115
Q
A
116
Q

How does the fluid mosaic model describe the structure of plasma membranes?

A
117
Q

Describe the structure of the rough endoplasmic reticulum.

A
118
Q
A
119
Q

For which macromolecule does a plant need both nitrogen and phosphorus?

A

DNA

120
Q

Explain how the Casparian strip prevents these ions from reaching the xylem of the plant by the apoplast pathway.

Soz icba to move this
A
121
Q
A
122
Q
A
123
Q
A
124
Q

ii

A
125
Q

Before the students began their investigation they made a hypothesis.
State the hypothesis the students would have made and state the scientific process that supports your choice.

A
126
Q

Justify whether the results from the investigation support your hypothesis given in part (b)(i).

A
127
Q
A

detect the
presence of acid /
H*

128
Q

Use the data in Table 22.1, on the insert, to calculate the rate of diffusion of acid in
Cube C from the outer surface to the centre of the cube.

A
129
Q
A
130
Q

Identify one limitation in the practical procedure that may have caused the results to be inaccurate and explain which cube’s results are most likely to have been affected by this limitation.

A
131
Q
A

idea of involvement of cytoskeleton / vesicles (1)

132
Q

Describe how the student should represent the data from Table 20 as a graph and explain why this is the correct way to represent these data.

A

line graph v
(because) both variables are continuous v
concentration on x / horizontal axis, because it is independent variable
AND
(%) change in mass on y/ vertical axis, because it is dependent

133
Q

Considering the data in Table 20, suggest three improvements to the design of this experiment. For each improvement explain how it will increase the validity of the data collected.

A
134
Q

Explain how the treatment results in the difference in the final lengths of rod A and rod E.

A
135
Q

Explain how the treatment results in the difference in the final lengths of rod D and rod F.

A
136
Q

State how the student could reduce the uncertainty of their data.

A

Use more precise apparatus

137
Q

The students identified replicate 3 of the potato in 0.7 mol dm 3 sucrose as anomalous.
Suggest a practical error by the students that might have caused this result to be anomalous and explain the likely effect of this error.

A

inadequate drying
more mass / heavier (than other pieces) v

138
Q

Use Table 16 to identify which plant cells contained the highest concentration of sucrose.
Justify your conclusion.

A
139
Q
A

Biology Module 2 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions