Cell Membranes

Front 1

Describe the 3 functions of the membrane at the surface of the cell

Back 1

Separating cell contents from the outside environment
Controls which substances enter and leave the cell
Cell recognition and signalling

Front 2

Describe the 3 functions of the membrane within the cell

Back 2

Divide cell into compartments making different functions more efficient
Can form vesicles
Control which substances enter and leave the organelle

Front 3

Describe the fluid mosaic model

Back 3

Phospholipid molecules from a continuous fluid bilayer
Various protein molecules are scattered through the bilayer some can move around
Glycoproteins
Glycolipids
Cholesterol

Front 4

Describe the role of cholesterol in the cell membrane

Back 4

Cholesterol molecules fit between phospholipid tails to make the membrane more rigid/more complete so water molecules and ions cannot pass easily through the membrane

Front 5

Describe the role of phospholipids in the cell membrane

Back 5

They are the component of the bilateral and molecules automatically arrange themselves so the hydrophilic heads face away and the hydrophobic tails face inwards

Front 6

Describe the role of glycolipids and glycoproteins in the cell membrane

Back 6

Cell signalling and recognition
Glycoproteins can bind cells together in tissues
Some receptor sites allow hormones to bind with the cell which causes the cell to respond in some way

Front 7

Outline the effects of changing temperature in membrane structure and permeability

Back 7

Increase in temperature gives molecules more kinetic energy so they move faster. This increased movements of phospholipids makes membranes more permeable

Front 8

Describe the role of channel proteins in the cell membrane

Back 8

Allows the movement of molecules that are usually too large and too hydrophilic to cross the membrane

Front 9

Describe the role of carrier proteins in the cell membrane

Back 9

Actively moves some substances across membrane using ATP

Front 10

Explain the term cell signalling

Back 10

One cell releases a messenger molecule, which travels to another cell where it binds to a receptor on the target cell membrane because the two have complimentary shapes, causing the target cell to respond in some way

Front 11

Explain the role of membrane bound receptors where hormones bind

Back 11

Hormones bind to a receptor because their shapes are complimentary e.g glucagon released when not enough glucose is in the blood. It binds receptors on the liver cells, causing them to break down stores of glycogen to glucose

Front 12

Explain the role of membrane bound receptors where drugs bind

Back 12

Drugs bind to a receptor because their shapes are complimentary. They either trigger a response or block the receptor and prevent it working

Front 13

A) what is passive transport
B) list three types

Back 13

A) no energy needed
B) diffusion, osmosis, facilitated diffusion

Front 14

What 6 things does diffusion depends on

Back 14

Temperature: hotter = more k.e
Surface area: larger = faster rate
Concentration gradient: higher = faster rate of diffusion
Mixing: increases k.e
Thickness of exchange surface: thinner surface = faster rate
Molecule size: smaller = faster

Front 15

Describe the role of phospholipids in the cell membrane

Back 15

They are the component of the bilayer and molecules automatically arrange themselves so the hydrophilic heads face away and the hydrophobic tails face inwards

Front 16

Define diffusion

Back 16

The movement of molecules from a high concentration to a lower concentration down a concentration gradient

Front 17

Define facilitated diffusion in carrier proteins

Back 17

Shaped so specific molecule fits in at membrane surface, once molecules is in, protein changes shape to allow molecule through to other side

Front 18

Describe active transport

Back 18

Refers to the molecule movement across membranes, which use ATP to drive protein pumps within the membrane

Front 19

Define endocytosis

Back 19

The bulk movement of materials into a cell

Front 20

Define exocytosis

Back 20

The bulk movement of materials out of a cell

Front 21

Define phago

Back 21

Solid material

Front 22

Define pino

Back 22

Liquid material

Front 23

List the differences between active transport and facilitated diffusion

Back 23

AT is active as uses ATP, FD is passive so kinetic energy, AT only carries molecules one way and opposite to concentration gradient, FD is slower, molecules can accumulate in AT

Front 24

Define osmosis

Back 24

The movement of water molecules from a high water concentration to a low water concentration across a partially permeable membrane

Front 25

Define water potential

Back 25

A measure of the tendency of water molecules to diffuse from one place to another

Front 26

Describe the role of glycolipids and glycoproteins in the cell membrane

Back 26

Cell signalling and recognition
Glycoproteins can bind cells together in tissues
Some receptor sites allow hormones to bind with the cell which causes the cell to respond in some way

Front 27

If an animal cell is placed in pure water what will happen

Back 27

The water enters cell by osmosis causing it to swell and eventually the membrane will bust (haemolysed)

Front 28

If a plant cell is placed in pure water what will happen

Back 28

The cell will gradually swell due to osmosis and the membrane will push on the cell wall but won't burst so it will become fully turgid

Front 29

If an animal cell is placed in a concentrated salt or sugar solution what will happen

Back 29

Water molecules move in to out by osmosis. Cell will shrink and membrane will wrinkle up (cremated)

Front 30

If a plant cell is placed in a concentrated salt or sugar solution what will happen

Back 30

Water molecules move in to out by osmosis. Cytoplasm and vacuole will shrink, cell surface membrane will pull away from cell well (plasmolysed)

Front 31

Define solute

Back 31

A solid that dissolves in a liquid

Front 32

Define solvent

Back 32

A liquid that dissolves solids

Front 33

Define solution

Back 33

A liquid containing dissolved solids

Front 34

Describe what the cell cycle consists of

Back 34

Mitosis only occupies a small percentage of the cell cycle the remaining being copying and checking genetic information on DNA and processes associated with growth

Front 35

If an animal cell is placed in pure water what will happen

Back 35

The water enters cell by osmosis causing it to swell and eventually the membrane will burst (haemolysed)

Front 36

Outline the effects of changing temperature in membrane structure and permeability

Back 36

Increase in temperature gives molecules more kinetic energy so they move faster. This increased movements of phospholipids makes membranes more permeable

Front 37

If an animal cell is placed in a concentrated salt or sugar solution what will happen

Back 37

Water molecules move in to out by osmosis. Cell will shrink and membrane will wrinkle up (crenated)

Front 38

If a plant cell is placed in a concentrated salt or sugar solution what will happen

Back 38

Water molecules move out by osmosis. Cytoplasm and vacuole will shrink, cell surface membrane will pull away from cell well (plasmolysed)

Front 39

Explain the term cell signalling

Back 39

One cell releases a messenger molecule, which travels to another cell where it binds to a receptor on the target cell membrane because the two have complimentary shapes, causing the target cell to respond in some way

Front 40

Explain the role of membrane bound receptors where hormones bind

Back 40

Hormones bind to a receptor because their shapes are complimentary e.g glucagon released when not enough glucose is in the blood. It binds receptors on the liver cells, causing them to break down stores of glycogen to glucose

Front 41

Explain the role of membrane bound receptors where drugs bind

Back 41

Drugs bind to a receptor because their shapes are complimentary. They either trigger a response or block the receptor and prevent it working

Front 42

What 6 things does diffusion depends on

Back 42

Temperature: hotter = more k.e
Surface area: larger = faster rate
Concentration gradient: higher = faster rate of diffusion
Mixing: increases k.e
Thickness of exchange surface: thinner surface = faster rate
Molecule size: smaller = faster