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A Level Biology - Cells > Transport Across Cell Membrane > Flashcards

Transport Across Cell Membrane Flashcards

1
Q

What is the model of the cell membrane called

A

Fluid Mosaic Model

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2
Q

Cellular membranes are formed from

A

A bilayer of phospholipids

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3
Q

Structure of a phospholipid (detail)

A

phosphate head - hydrophilic - soluble in water
Glycerol and 2 fatty acid chains - hydrophobic - insoluble in water

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4
Q

Intrinsic proteins are….

A

Embedded in the membrane

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5
Q

Extrinsic proteins are

A

Found on the outer or inner surface of the membrane

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6
Q

What 3 types of lipids do cell membranes contain

A

Phospholipids
Cholesterol
Glycolipids

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7
Q

Is cholesterol found in eukaryotic or prokaryotic membranes

A

Only eukaryotic
NOT in prokaryotic

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8
Q

What is the function of cholesterol in the cell membrane

A

Helps maintain membrane stability ( holds the phospholipids together more tightly)
Prevents fluidity under too warm conditions and too ridge under cool conditions
Reduces movement of water soluble chemicals

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9
Q

What is the structure of a glycoprotein

A

Proteins with a carbon chain attached

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10
Q

What is the function of glycoprotein and glycolipid

A

Involved in cell signalling

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11
Q

What type of amino acids do intrinsic proteins have

A

Hydrophobic

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12
Q

What are the two types of intrinsic proteins

A

Channel
Carrier

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13
Q

Protein channel allows (what goes through)

A

Protein channels allow polar molecules and ions to diffuse through

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14
Q

How do carrier proteins work

A

Change shape or position
To transfer molecules or ions from one side to another

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15
Q

Function of glycoprotein x4

A

Cell recognition
Allow cells to attach to each other
Role in immune system
Receptors for hormones

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16
Q

Define diffusion

A

Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration

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17
Q

What are the 6 factors that affect diffusion

A

Concentration gradient
Particle charge/size
Temperature
Thickness of exchange surface
Facilitated diffusion
The surface area

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18
Q

What is simple diffusion

A

When molecules diffuse directly through the cell membrane

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19
Q

Diffusion is a. ….. process this means …

A

Passive
It does not need metabolic energy

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20
Q

What happens on facilitated diffusion

A

Hydrophilic substances diffuse across the cell membrane via proteins

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21
Q

What type of protein are carrier and channel proteins

A

Intrinsic

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22
Q

How do carrier proteins work

A

Have a binding site for a specific chemical
Tertiary structure of the carrier protein changes
The chemical is then released on the opposite side of membrane

23
Q

How does a channel protein work

A

Protein with a pore
Lined with hydrophilic amino acids and contains water
Hydrophilic substances pass from one side to another

24
Q

Define osmosis

A

Osmosis is the movement of water molecules from a region of higher water potential to the region of lower water potential through a partially permeable membrane

25
Q

Define water potential

A

The likelihood of water molecules to diffuse in or out of a solution
(One that exerts more pressure)

26
Q

Water potential of pure water

A

0

27
Q

What is the unit of water potential

A

Kilo pascals
kPa

28
Q

More concentrated solution has
….. water potential
More ….. value

A

Lower
Negative

29
Q

Define isotonic

A

Is when water potential on both sides of the membrane is equal

30
Q

Define hypertonic

A

Water moves out
Water potential of the solution is more negative than the cell.

31
Q

Define hypotonic

A

Water moves in
When the water potential of a solution is more positive than the cell

32
Q

Active transport definition

A

The movement of molecules and ions against the concentration gradient, from a region of low to a region of high concentration. The process requires energy using ATP

33
Q

How does active transport work

A

The molecule or ion attaches to receptor site on the carrier protein. (on the side of the membrane where the chemical is at a lower concentration).
ATP bonds to carrier protein
ATP hydrolyses
Phosphate attaches to carrier protein
Protein changes shape and then returns to original shape

34
Q

Give two functions of the phospholipids in the cell membrane

A

Allows non-polar molecules to pass through
Gives fluidity/flexibility to cell membrane

35
Q

Why data in table above is processed results

A

Calculations are made from raw data they would have found x and y to do calculation

36
Q

What is the bond between the glycerol and fatty acid chains called

A

Ester

37
Q

A prokaryotic cell does not have cholesterol but still maintains shape explain why (2)

A

Cell is unable to change shape
Due to cell wall

38
Q

How could a student use cylinders to to cut the potato/carrot etc to ensure it was a fair test

A

Cut the cylinders from the same area
Cut the carrot lengthways down the root

39
Q

Other then the membrane outside of the cell where else can you find the membrane x3

A

Lysosomes and mitochondria and chloroplasts

40
Q

Which can pass through the cell membrane hydrophilic or hydrophobic

A

Hydrophobic
Because the centre is hydrophobic
Hydrophilic substances are polar so can’t pass through

41
Q

What can pass through the cell membrane

A

Non-polar (centre is non polar hydrophobic)
Water can pass even though polar because they are extremely small

42
Q

Function of glycolipids

A

Recognise other cells and determine wether to come into contact
Antigens to determine blood group

43
Q

Limitation imposed by the nature of the phospholipid bilayer relating to diffusion

A

The cell membrane contains a hydrophobic core charged particles can’t diffuse through (excluding water)

44
Q

does facilitated diffusion use energy

A

NO passive process still diffusion

45
Q

What is used in co-transport

A

Sodium-potassium pump which pumps sodium ions out of the epithelial cells into the blood stream

46
Q

Co-transport in terms of sodium ions

A

Sodium glucose transporter protein between gut and epithelia cell
Sodium ions diffuse through down their concentration gradient and at the same time glucose (against concentration gradient)

47
Q

Adaptation of epithelial cells that help with co-transport

A

Large number mitochondria for potassium-sodium pump
Large number microvilli increase surface area more space for proteins
Blood stream carrier away the glucose maintains concentration gradient for facilitated diffusion.

48
Q

What type of protein does co-transport use

A

Carrier protein

49
Q

Explain the arrangements of the phospholipids in a cell-surface membrane

A

It is a bilayer
Hydrophobic tails point away FROM WATER / Hydrophilic heads point toward (attracted) TO WATER

50
Q

Which are polar and non- polar in a phospholipid

A

Fatty acid- non-polar
Heads + polar

51
Q

Which protein does co-transport and active transport use

A

Carrier

52
Q

Describe how substances can cross the cell membrane

A

Simple
Facilitated
Osmosis
Active transport

53
Q

How to do calibration curve

A

Make solutions of known concentration
Use colorimeter to value each solution and plot calibration curve
Find concentration of sample from calibration curve

A Level Biology - Cells (6 decks)

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