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Biology AS Level > Cell Memebranes T4 > Flashcards

Cell Memebranes T4 Flashcards

1
Q

Most fluid CSM

A
  1. Increase prop of phospholipids w/ unsaturated fatty acid chains = kinks prevent closer packing + maintaisn membrane fluidty to maintain movement of subst across membrane
  2. Increase Temp
    3.Chosterol
  3. C=C in fatty acid chains
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2
Q

Least fluid CSM

A
  1. Increase in proportion of phospholipids w/ saturated fatty acid chains
  2. Increase proportion of longer fatty acid chains
  3. Less C=C in fatty acids chains
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3
Q

As fluidity of CSM decreases, what transport least effected?

A
  1. Active transport
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4
Q

Why is dye evenley distributed in lipid belayer?

A
  • Protein molecules in outer layer of CSM + those which span bilateral MOVE FREELY between phospholipid molecules.
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5
Q

Cells w highest proportion of single membrane bound structures?

A
  • Goblet cells
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6
Q

Increase x bond helps to increase fluidity?

A
  • C=C (carbon to carbon double bond)
  • unsaturated fatty acids = bend fatty acid chain
  • less tightly packed + less IMF between mols = MORE FLUID
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7
Q

Which sequence leads to viruses invading cell

A
  • binding to glycoprotein receptor & endocytosis
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8
Q

Roles of cholesterol, glycoproteins, phospholipids and proteins

A
  • regulates membr fluidity + converted to steriod H
  • Cell recognition
  • Seperating dissolved proteins
  • Transporting ions through membranes
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9
Q

FLUID MOSIAC MODEL

A
  • Fluid
  • Phospholipid molecules differ
  • Protein molecules scattered
  • Different protein molecules
  • pattern produced when scattered proteins arrange themselves in the CSM (when viewed from above)
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10
Q

Why are channel proteins IMPT in movement of water through CSM? (6m)

A
  1. Water mols are polar
  2. Few polar mol pass through phospholipid belayer
  3. Hydrophobic core
  4. Channels through X are hydrophilic
  5. increases permeability of membrane to water
    - protein has quat ss + globular
    - hydrophilic parts of protein face aqueous enviornemt
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11
Q

Endocytosis occur @ CSM (6m)

A

1 Attachment of bacteria to receptors
2 ability to attach to antibody (bound to antigen on bacterium)
3 infolding/invagination
4 membrane engulfs
5 form round bacterium
6 fusion —> formation of vesicle

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12
Q

Explain how features of phospholipids form a layer

A
  1. Polar
  2. Attracted to water/aqueous environment
  3. H+ bonding (polar head faces water)
  4. Non- polar/hydrophobic tails
  5. Repelled/away from water/aqueous environment
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13
Q

Role of channel proteins - 4m + description

A
  • intergral intrinsic membrane protein (exterior hydrophobic)
  • Channel allows polar/water soluble mols
  • forms hydrophillic pores across membrane
  • hydrophilic mol to pass through membranes
  • facilitated diffusion + AT
  • cellular recognition
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14
Q

Why don’t Ca+ ions pass though phospholipid biller- 3m

A
  • Ca+ hydrophilic/ not lipophillic or lipid soluable
  • Ionic
  • Phospholipid belayer is hydrophobic
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15
Q

Describe how Ca+ ions move across membranes-5m

A
  1. Active transport
  2. Ca+ ions moved against their conc gradient
  3. Carrier protein
  4. Ca+ ions combine w/ binding site
  5. Carrier protein —-> conformational change/ATP
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16
Q

Describe function of lysosomes destroying bacteria

A
  1. lysosomes fuse w/ vesicles
  2. Form secondary lysosomes
  3. Lysosomes contain enzyme catalyse/digestion/hydrolysis
  4. Phospholipid/nuclei acid
  5. Peptide/ester bond
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17
Q

Functions of CSM

A
  1. Facilitated diffusion
  2. Endocytosis/excosytosis
  3. Cell recognition
  4. Barrier to polar molecules
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18
Q

How X ions + non polar move in CSM

A
  1. Active transport
  2. Carrier protein
  3. Pumped against conc gradient/low to high using ATP
  4. Binding to receptor site/conformational change
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19
Q

Describe how proteins become denatured @ high temp + leads to damaged CSM/

A
  1. Loss of tertiary SS// loss of AS shape/denatured
  2. Loss of globular structure
  3. Breakage of ionic/hydrogen/hydrophobic bonds
  4. Loss of function of membrane proteins
  5. Transport of polar molecules impaired
  6. Disrupts interaction between protein + phospholipid belayer
  7. Membrane becomes leaky/less partially permeable
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20
Q

Bulk transport vs exocytosis

A
  • movement of large molecules s e.g proteins, polysaccharides, endocytosis/exco
  • ATP needed for process

-1. Vesicle containing mol moves toward CSM
- membrane of vesicles fuses w CSM
2. Membrane engulfs mol inward
3. Membrane pinched off
4. ATP required

21
Q

Suggest and explain what would happen to bacteria placed in solution w/ water potential more negative than cell?

A
  1. Cell cytoplasm/contents shrink
  2. Plasmolysis occurs/CSM peels away from Cell wall
  3. Movement of water out via osmosis
  4. Down water potential gradient/ high to low water potential

Low water potential = more negative
High water potential = more positive

22
Q

Osmosis in plant cell: placed in pure water/negative water potential

A
  1. Plant cell placed in pure water/dilute solution
  2. Water enters plant via osmosis through ppm
  3. Pure water/dilute solution = high water potential than cell ‘(more NEG)
  4. As water enters vacuole of cell —> Vol of cell increases
  5. Expanding protoplast pushes against cell wall + pressure increases in cell
  6. In elastic cell wall prevents cell lysis in hypotonic sol
  7. Plant cell fully inflated w water—-> turgid fully
23
Q

Osmosis Plant cells: concentrated solution

A
  1. Plant cell placed in concentrated solution w/ low water potential
  2. Water leaves vacuole cell via osmosis through ppm —-> vol of cell decreases
  3. Protoplast shrinks + no pressure exerted on cell wall
  4. Protoplast continues brining + pulls away from cell wall
  5. Plasmolysed/Plasmolysis - hypertonic solution
24
Q

Osmosis Animal cell: Concentrated solution w lower water potential than cell

A
  1. Placed in conc sol w lower water potential then cell
  2. water will leave cell through ppm via osmosis
  3. Cell will shrink + shrivel up —>crenation/crenated
  4. Occurs in hypertonic environment, cell has lower solute conc
25
Q

Animal cell:Isotonic

A
  1. Cell placed in isotonic environment/cell has same sol conc
  2. Movement of water in and out of cell occurs at same rate (no net movement of water)
  3. No change to cells
26
Q

Cell signaling definition

A
  • Molecular mechanism by which cells detect and reason to external stimuli, including communication between cells.
27
Q

Example of ligand

A
  • Hormone glucagon (released from pancreas) or adrenaline from adrenal glands.
28
Q

Transport mechanism across CSM for oxygen

A
  • Passive/simple diffusion
29
Q

Transport mechanism for glucose,AA,ions,water

A
  • facilitated diffusion
30
Q

Protein involved in passive process =

A
  • Facilitated diffusion
31
Q

Protein involved in active process =

A
  • Active transport OR sodium potassium pump
32
Q

NO Protein involved and passive process=

A
  • Osmosis/diffusion
33
Q

NO protein involved in active process=

A
  • Endocytosis/excoytosis/pinocytsosis
34
Q

Name and explain the process by which water moves into the lumen

A
  • osmosis
  • increasing solute conc in lumen lowers water potential
  • water moves from a higher to lower water potential down water potential gradient
35
Q

Describe correct sequence of events in cell signaling pathway

A
  1. Protein receptor conformational change
  2. G-Protein activation
  3. Enzyme catalyses reaction
  4. 2nd messenger production
36
Q

carrier proteins//intrinsic protein

A
  • require energy
  • go against the concentration gradient
  • take substances from outside and pumps it inside or vice versa
  • used for active transport
  • interior = hydrophillic
37
Q

Factors affectiong the rate of diffusion

A

STEEPNESS OF CONCENTRATION GRADIENT
TEMPERATURE
SURFACE AREA
NATURE OF MOLECULES/IONS

38
Q

Water potential Ψ + factors affecting

A

-tendency of water to move out of a solution
-pure water has 0
-solutions have a negative Ψ

-how much water is in solution compared to the amount of solutes
-how much pressure is applied to it (by cell wall)

39
Q

do plant cells and prokaryotes have cholesterol in their membranes?

A

plant cells have very little and prokaryotes do not, they both have another compound which does the same thing

40
Q

how do glycolipids and glycoproteins stabilise the membrane structure?

A

they project into the watery fluids surrounding the cell and form hydrogen bonds with wwater
- glycolipid= hydrophillic carbohydrate chain (made of monosaccharides)

41
Q

what is glycolax?

A

sugary cell coating formed by carbohydrate chains on glycoproteins and glycolipids

  • made of glycoprotein = ANIMAL CELLS
  • made of glycolipids = PLANT CELLS
42
Q

IMF interactions that drives bilayer formation when phospholipids added to water

A
  • H+ stronger than IMF —> more energy needed to overcome bonds
  • phospholipid CANNOT replace H+ w water lost due to lipid insertions
  • Water makes cage like structure around lipid = bad as reduces freedom of water mol + number of H+
  • forcing lipids into bilayer reduces this effect
43
Q

Why would phospholipids dissolve in ethanol

A
  • ethanol is mols hydrophobic chain + hydrophillic (OH) polar group
  • phospholipid contain hydrophobic and hydrophillic parts = dissolve in ethanol
44
Q

stem cell signalling

A
  • Undiffrentiated
  • exposed to chemical e.g hormone
  • produces transcription factor
  • binds to promotor region w/ DNA
  • switches gene on + transcription
  • Mrna leaves nucleur pore to ribosome for translsatoion = protein/polypeptide syntheized
  • cell speciliased
45
Q

Cell signalling: PEPTIDE

A
  • PH binds to protein receptor on glycoprotein
  • PH cannot cross membrane - hydrophilic
  • Protein receptor undergoes a conformational change
  • Activating G protein = releasing chemical activating enzymes in the membrane
  • 2nd messanger//cAMP activates enzyme cascade
  • amplifying signa; + where inactive enzymes become activated
    -small product = transcription factor + squeeze though nucleur pore entering nucleus
46
Q

Transcription factor movement

A

Binds to promotor region on DNA strand
- w/ rna polymerase
- forming transcription initation complex
- switching gene on by allowing transcription
- mrna produced + leaves through nucluer pore to cytoplasm –> bind to ribosome for translation

47
Q

Cell Signalling: STERIOD HORMONE

A
  • diffuses across membrane- hydrophobic
  • binds to specific receptors in cytoplasm
  • transcription factor
  • forming transcription initiation complex
  • switching genes on by allowing transcription
  • mRNA produced + leaves through nuclear pore to cytoplasm –> bind to ribosome for translation
48
Q

suggets how oestrogen causes breast cancer

A
  • Oestrogen is SH affecting transcription
  • binds to receptor in cytoplasm of target cells = transcription factor –> oestrogen recptor complex
  • TF binds to promotr region that regulates cell division w/ RNA polymerase binding to PR
  • transcriotion initation complex
  • gene switched on = oncogene
  • trnscritption = mrna produced + leaves via nucleur pore to cytoplasm
  • binds to ribosome for translation = tumor
49
Q

2 mol combing w cholestrol to form LDLs

A
  • protein + lipids

Biology AS Level (12 decks)

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