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AS biology > 2.5 cell membranes > Flashcards

2.5 cell membranes Flashcards

1
Q

no. membranes around nucleus

A

2

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2
Q

no. membranes around ER

A

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3
Q

no. membranes around GOLGI

A

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4
Q

no. membranes around LYSOSOME

A

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5
Q

no. membranes around CHLOROPLAST

A

2

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6
Q

no. membranes around MITOCHONDRIA

A

2

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7
Q

partially permeable defintion

A

allows some substances to pass through but not all

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8
Q

purpose of plasma membrane

A
  1. BARRIER : controls movement of substances in and out of the cell (cell membrane)
  2. Compartmentalisation (golgi apparatus)
  3. cell signalling (receptors on csm)
  4. electrical communication (nerve csm)
  5. attachment site for enzymes (inner membrane of mitochondria)
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9
Q

phopholipid properties

A
  • hydrophilic head (charged)
  • hydrophobi tails (uncharged)
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10
Q

phospholipid bilayer orientation

A

orientate so that hypdrophilic heads are faced towards water and hydrophobic tails away from water
- can form a micelle (sphere) HPI heads outside and in the middle

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11
Q

7 components of CSM

A
  1. glycoprotein
  2. glycoplipid
  3. phospholipid bilayer
  4. cholestrol
  5. channel / carrier protein
  6. extrinsic protein
  7. actin microfilament
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12
Q

fluid mosaic model

A
  • phospholipid bilayer
  • hydophilic heads facing external environment
  • hydophobic tails away from external environment
  • proteins free to move inside membrane
  • proteins randomly arranged throughouy
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13
Q

cholestrol

A
  • 4 carbon rings
  • regulates fluidiity of membrane
  • ONLY IN EUKARYOTIC
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14
Q

channel proteins

A
  • ALLOW facilitated diffusion to happen
  • only specific substances can diffuse through
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15
Q

carrier proteins

A
  • change shape to allow specific substances through
  • facilitated diffusion AND active transport
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16
Q

glycoproteins and glycolipids

A
  • polysaccharaide chain attached to lipid or protein
  • act as antigens for cell recognition (tissue formation)
  • receptors for cell signalling
17
Q

temperature effect on membranes

A
  • as temp increaes, KE increases
  • membrane bceoms more fluid
  • gaps created
  • more permeable
18
Q

organisms in COLD environments membranes

A
  • MORE cholestrol to prevent membrane freezing
  • more UNSATURATED and SHORTER fatty acid tails to make it more fluid
19
Q

organisms in HOT environments membrane adaptation

A
  • more SATURATED and longer fatty acid tails to make membrane less fluid
20
Q

role of membrane bound receptors for hormones and drugs to bind

A
  1. a receptor (glycoprotein or glycolipid) on the outer surface of the membrane has a BINDING SITE complementary in shape to the hormone or drug
  2. hormone or drug is the ‘first messenger’. it binds to the receptor which then activates enzymes in the membrane
  3. the enzymes activate a scong messenger which then has an effect on cellular function
21
Q

what can diffuse across with simple diffusion?

A
  • small
  • non polar
  • FAT SOLUBLE (eg lipid) molecules
22
Q

channel proteins are involved in

A

facilitated diffusion

23
Q

carrier proteins are involved in

A

(facilitated diffusion) AND active transport

24
Q

endocytosis transports …

A

large quantities of material out of the cell

25
Q

describe endocytosis

A
  1. membrane folds in around the solid OR liquid
  2. fuses with itself and pinches off, forming a vesicle
  3. triggers by binding of molecule to receptor site
  4. vesicle moves through cytoplasm
    USES ATP
26
Q

how does the active transport using proteins work

A
  • carrier protein changes shape using ATP
  • AT pump (protein) is shaped so that the molecule being carried fits to one side only
27
Q

how to describe permeability when using the proteins

A

selectively permeable

28
Q

extrinsic proteins

A

proteins held on the outer surface of the membrane

29
Q

2 examples of what cannot go across by simple diffusion

A
  • water
  • ions
30
Q

how does cholestrol work

A
  • fits between the tails of phospholipids
  • inhibits their movement, reducing fluidity
31
Q

waht happens if the temp is too high

A
  • loses mechanical stability
  • fully permeable
  • proteins denature
32
Q

effect of solvents like alcohol

A
  • dissolve fatty substances by inserting into bilayer and breaking IMFs
33
Q

OTHER use of cholestrol

A

steroid hormones
- make vitamin D
- make bile salts

34
Q

3 example of active transport

A
  • mineral ions into root hair cells
  • h+ out of companion cells
  • sucrose out of sieve tube at sink
35
Q

freezing effect on permeability

A

increases

36
Q

how does x pass through membrane

A
  • non-polar lipid
  • soluble in the phospholipid bilayer so can pass through
37
Q

why is rate of transport not constant in active transport

A
  • uses carrier proteins
  • proteins become saturated

AS biology (14 decks)

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