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Biology module 2 > Biological Membranes > Flashcards

Biological Membranes Flashcards

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1
Q

What 2 places can you find membranes?

A

Around a cell and around Eukaryotic organelles

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2
Q

What do membranes do?

A 
Controls what enters and leaves
Selectively/partially permeable
Responsible for compartmentalisation
Site of cell receptors and cell signalling
Site of chemical reactions
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3
Q

What are some examples of where membranes are important?

A

Rough ER- ribosomes attach to it
Lysosomes-contain the acid/enzymes which would damage the cell if they were free
Mitochondria- contain respiratory enzymes

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4
Q

What are the 4 parts of a membrane?

A

Cholesterol
Phospholipid bilayer
Glycoproteins/glycolipid
Channel/carrier proteins

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5
Q

Cholesterol

A

Type of lipid with hydrophilic/phobic end
Lie alongside phospholipids
Regulates fluidity of membrane
Too stiff-stops phospholipids grouping together and crystallising
Too fluid-hydrophilic end interacts with head and hydrophobic end interacts with tail of phospholipids pulling them closer together.

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6
Q

Phospholipid bilayer

A

2 layers
Hydrophilic head (glycerol and phosphate) on the outside
Hydrophobic tail (fatty acid) on inside
Fluid (can move)
Prevent water soluble substances from passing through.
Only small uncharged particles can pass through.

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7
Q

Glycoproteins/lipids

A 
Sugars stuck to protein/lipid
Receptors for molecules, like hormones, to bind
Help cells join together
Cell signalling
Cell recognition
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8
Q

Carrier/channel proteins

A 
Can be intrinsic (go all the way through) or extrinsic (only on 1 side)
Channel proteins (intrinsic) allow hydrophilic substances like ions to get through
Carrier proteins (intrinsic or extrinsic) change shape up let molecules through
Carry charged/large molecules across
Normally specific to a molecule
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9
Q

What if the fluid mosaic model?

A

Fluid because the phospholipids are able to move past each other.
Mosaic because the other components are places all around the membrane.

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10
Q

How wide are membranes?

A

7nm

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11
Q

Definition of diffusion

A

Movement of particles from an area of high concentration to an area of low concentration, down the concentration gradient until an equilibrium is reached
No extra energy is needed

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12
Q

Factors that affect diffusion

A 
Concentration gradient
Temperature
Stirring/moving 
Surface area
Type/size of ion/molecule
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13
Q

4 examples of molecules that can diffuse across the cell surface membrane

A

Oxygen (very small and uncharged)
Carbon dioxide (very small)
Water (very small)
Fat soluble substances (dissolve in phospholipids to get across)

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14
Q

3 molecules that can’t diffuse across cell membranes

A 
Ions (small but charge repels them)
Glucose (too big)
Amino acids (too big)
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15
Q

Definition of facilitated diffusion

A

Movement of particles from an area of high concentration to an area of low concentration, down the concentration gradient, with the aid of a channel/carrier protein until an equilibrium is reached
No extra energy is needed as particles have their own kinetic energy

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16
Q

What things use facilitated diffusion?

A

Anything that can’t pass through using normal diffusion (ions, glucose, amino acids etc)

17
Q

What factors affect facilitated diffusion?

A 
Concentration gradient
Temperature
Stirring/moving
Surface area
Type/size of ion/molecule 
AND
NUMBER OF CHANNEL/CARRIER PROTEINS
18
Q

Definition of osmosis

A

Movement of water molecules from an area of higher water potential to an area of lower water potential through a partially permeable membrane down the water potential gradient

19
Q

What is the highest water potential number?

A

0 (every other water potential number is below 0)

20
Q

Which 3 types of transport across membranes are passive?

A

Simple diffusion
Facilitated diffusion
Osmosis

21
Q

Which transport across membranes is active?

A

Active transport

22
Q

Which types of transport across membranes don’t need extra energy?

A

Simple diffusion
Facilitated diffusion
Osmosis
(They just need kinetic energy)

23
Q

Where does the energy for active transport come from?

A

ATP

24
Q

Which types of transport across membranes use a protein?

A

Facilitated diffusion (carrier or channel)

Active transport (must be carrier)

25
Q

What is bulk transport?

A 
Lots of substances/molecules being transported at once.
Requires ATP (this is a type of active transport)
26
Q

What does pino exocytosis mean?

A

Bulk movement of liquid out of a cell

27
Q

What does pino endocytosis mean?

A

Bulk movement of liquid inside a cell

28
Q

What does phago exocytosis mean?

A

Bulk movement of a solid out of a cell

29
Q

What does phago endocytosis mean?

A

Bulk movement of a solid inside of a cell

30
Q

In which 2 organelles are membranes involved in chemical reactions?

A

Mitochondria

Chloroplasts

31
Q

How are membranes involved in cell signalling?

A

Membranes contain receptors for signalling molecules. When the signalling molecule binds to the receptors, it triggers a series of reactions within the cell.

32
Q

How do drugs that bind to receptors on membranes work?

A

The drugs may be a similar shape to the signalling molecule so bind to the receptor and block it, reducing/increasing the response.

33
Q

What is ATP specifically used for in exocytosis and endocytosis?

A

Moving vesicles

Used so vesicles can fuse to the plasma membrane

34
Q

What is the difference between simple and facilitated diffusion?

A

Simple doesn’t need any membrane proteins.

Facilitated requires carrier/channel proteins because molecules are too big to pass through the membrane.

35
Q

How is ATP used in exocytosis?

A

Makes the membranes ‘pinch off’ to form vesicles

Moves the vesicles around the cell

Biology module 2 (19 decks)

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