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AQA A-Level Biology Year 1 > Membranes > Flashcards

Membranes Flashcards

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1
Q

What is the role is cholesterol ?

A

adds strength

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2
Q

What is the fluid - mosaic model?

A

the structure of membrane

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3
Q

what is an intrinsic protein ?

A

spans the whole membrane

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4
Q

What is the arrangement of phospholipids

A

phospholipid bilayer

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5
Q

What is the hydrophobic region?

A

fatty acid tails

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6
Q

What is the hydrophilic region?

A

the phosphate head

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7
Q

what is the majority lipid in a membrane

A

phospholipid

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8
Q

what is an extrinsic protein?

A

loosely bound to outside of a membrane

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9
Q

What is a passive process

A

does not require ATP

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10
Q

What is osmosis?

A

movement of water down water potential gradient

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11
Q

what is a glycoprotein?

A

a protein with a carbohydrate attached

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12
Q

what is a glycolipid?

A

a lipid with a carbohydrate attached

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13
Q

What is a carrier protein?

A

changes shape to transport substances across membrane

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14
Q

What is the role of proteins in membranes

A

enzymes
receptors
transport
recognition

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15
Q

what is a channel protein?

A

molecules travel through them in facillitated diffusion

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16
Q

what is diffusion?

A

random movement of molecules from high to low concentration

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17
Q

What is active transport?

A

move against concentration gradient

18
Q

what is endocytosis?

A

moving large molecules into cells

19
Q

What is exocytosis?

A

Moving large molecules out of cells

20
Q

Why are membranes fluid?

A

hydrophobic and hydrophilic interactions

phospholipids and proteins can move horizontally

no bonds

21
Q

What is the importance of a membrane being fluid?

A

can repair itself

flexible

for endocytosis and exocytosis

22
Q

How does a protein stay in the membrane?

A

Has no charge in the middle, and charge in the outside

Charged amino acids are either highly hydrophobic or hydrophilic, uncharged amino acids go in the middle

23
Q

What travels through channel proteins?

A

ions, water solvable substances

24
Q

What is the structure and properties of a membrane?

A

phosphate head - hydrophilic

Fatty acid tails - hydrophobic

selectively permeable

25
Q

What is diffusion

A

high concentration to low concentration

down a concentration gradient

passive

26
Q

How to calculate rate of diffusion

A

amount diffused / time taken

27
Q

What factors effect rate of diffusion?

A

temperature, surface area, different in concentration and thin exchange surface

28
Q

What is facilitated diffusion?

A

larger water soluable molecules

carrier proteins with binding sites

specific

passive

29
Q

What is osmosis?

A

cytoplasm contains soluable molecules and ions which attract water

net movement of solvent molecules from an area lower loconcentration to higher concentration of solute

depends of water potential

30
Q

osmosis

what happens if an animal cell in solution with a lower water potential?

A

net movement out of cell

31
Q

osmosis

what happens to a plant cell in solution with lower water potential

A

contents shrink away from cell wall

32
Q

Osmosis

what happens to an animal cell in solution with higher water potential

A

bursts

33
Q

osmosis

what happens to a plant cell in solution with higher water potential

A

becomes firm and rigid

34
Q

what is active transport?

A

against a concentration gradient

uses carrier proteins and requires ATP

35
Q

What is an example of active transport?

A

epithelial cells lining the intestine, lots of mitochondria which produces ATP for active transport

36
Q

How does active transport occur?

A

molecules bind to receptor site

atp binds to protein , hydrolysed into ADP and Pi

Protein changes shape

Molecule is released

Pi is released, protein reverts to original shape

37
Q

what is water potential

A

the tendency of water to move from one area to another by osmosis

measured in kPa

38
Q

what is the water potential of pure water

A

0

39
Q

what is hypertonic

A

higher concentration of solutes when compared to another solution

40
Q

what is hypotonic

A

lower concentration of solute when compared to another solution

41
Q

what is isotonic

A

same solute concentration in two or more solutions

AQA A-Level Biology Year 1 (6 decks)

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