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AH Biology > Cells and proteins - 3 > Flashcards

Cells and proteins - 3 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what makes up the fluid mosaic model?

A
  • phospholipid bilayer

- globular protein

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2
Q

what does the hydrophobic centre of a membrane allow?

A

allows oxygen and carbon dioxide to pass through since they are small non-polar molecules

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3
Q

what does the hydrophobic centre act as a barrier to?

A

acts as a barrier to the passage of charged ions and most polar molecules

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4
Q

what are integral proteins?

A

proteins embedded in the bilayer

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5
Q

what type of interactions do integral proteins form?

A

form strong hydrophobic interactions

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6
Q

what type of integral proteins span across the width of the membrane?

A

transmembrane proteins

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7
Q

what are peripheral proteins?

A

proteins that are not embedded in the bilayer

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8
Q

what type of bonds do peripheral proteins form?

A

form weak bonds to the surface of the membrane

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9
Q

whereabouts on the membrane do peripheral proteins bond to?

A
  • heads of phospholipids

- integral proteins

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10
Q

what is a ligand?

A

any substance that can bind to a protein

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11
Q

what does a binding of a ligand cause?

A
  • conformational change (change in shape)

- change in function

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12
Q

what does protein folding produce?

A

ligand-binding sites on the surface if the protein

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13
Q

what are ligand-binding sites complementary to?

A

complementary shape and chemistry to their ligand

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14
Q

what is DNA tightly coiled around?

A

histone proteins to form nucleosomes

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15
Q

how does DNA act as a ligand?

A

DNA binds since the negative-charged phosphates of DNA interact with positive-charged R groups on outside of histone

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16
Q

the active site of an enzyme is an example of what?

A

a ligand-binding site

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17
Q

when enzymes bind to the substrates is there a high or low affinity?

A

high affinity

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18
Q

what is a modulator?

A

molecules that bind to secondary sites of enzyme

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19
Q

what is a negative modulator?

A

inhibits enzyme activity

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20
Q

what is a positive modulator?

A

activates enzyme activity

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21
Q

how do modulators occur?

A

by altering the affinity to a substrate

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22
Q

what is co-operativity?

A

when binding of a molecule to a subunit increases affinity for the other subunits until saturated

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23
Q

explain haemoglobin as an example of co-operativity

A
  • as oxygen binds to one subunit
  • affinity of the other subunits change
  • increases number of oxygen collected
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24
Q

what does addition/removal of a phosphate cause?

A

causes a reversible conformational change

25
Q

what is the addition/removal of a phosphate carried out by?

A

carried out by enzymes

26
Q

what is the addition/removal of a phosphate important for?

A

important in regulation of activity of proteins

27
Q

what do kinases do?

A
  • catalyse phosphorylation

- adds phosphates

28
Q

what do phosphates do?

A
  • catalyse dephosphorylation

- removes phosphates

29
Q

what are ATPases?

A

enzyme that releases a phosphate from ATP

30
Q

how to ATPases work?

A

by phosphorylating themselves

31
Q

during muscle contraction, what forms the cross bridges?

A

binding of myosin head to actin

32
Q

during muscle contraction, what does the binding of ATP cause?

A

causes a conformational change

33
Q

during muscle contraction, what causes the third conformational change?

A

the myosin head rebinding to actin

34
Q

during muscle contraction, when the ADP + Pi is released from myosin, what does the myosin do?

A

myosin head swings back dragging actin filament along

35
Q

what are the two types of transmembrane proteins?

A
  • channel proteins

- transporter proteins

36
Q

what is the purpose of transmembrane proteins?

A

needed to allow movement of molecules into and out of the cell

37
Q

is ATP required to move molecules through channel proteins?

A

no it is passive transport

38
Q

what are aquaporins?

A

ungated channel proteins which allow the free movement of water molecules

39
Q

what allows ions to move through a ligand gated channel?

A

when a protein or ligand attaches to the channel causing conformational change

40
Q

when will a voltage-gated channel open?

A

opens if there is an ion concentration difference on the inside and outside of cell

41
Q

if a transporter protein is active it requires what?

A

ATP

42
Q

what are the functions of the sodium potassium pump?

A
  • maintenance of osmotic balance in cells

- generates an ion gradient in kidney tubules and neurons

43
Q

in the sodium potassium pump what changes the conformation to allow the Na ions to be released out of the cell?

A

a phosphate from hydrolysis of ATP binding to the pump

44
Q

how many sodiums bind to the sodium potassium pump?

A

3 Na

45
Q

how many potassiums bind to the sodium potassium pump?

A

2 K

46
Q

is the sodium potassium pump active or facilitated?

A

active

47
Q

what does the glucose symport do?

A

transports glucose from a low to high concentration

48
Q

is the glucose symport active or facilitated?

A

facilitated

49
Q

how many sodiums are transported in the glucose symport?

A

2 Na

50
Q

what are receptor proteins?

A

proteins that have specific binding sites for extracellular hydrophilic signal molecules

51
Q

what causes a conformational change in receptor proteins?

A

the binding of chemical signal which triggers a signal transduction pathway

52
Q

when a signal transduction pathway is triggered what does this cause?

A

causes a specific intracellular response

53
Q

what can a signal transduction pathway involve?

A
  • activation of enzyme or G protein
  • a change in uptake or secretion of molecules
  • activation of proteins that regulate gene transcription
  • rearrange the cell’s cytoskeleton
54
Q

what is nerve transmission?

A

a wave of depolarisation of a resting potential

55
Q

what is nerve transmission stimulated by?

A

stimulated by a signal molecule to open ligand gated channels at synapse

56
Q

what does the opening of a ligand-gated channel in nerve transmission allow?

A

allows enough Na ions movement to undergo depolarisation

57
Q

once depolarisation has passed, what makes the neuron’s membrane potential negative again?

A
  • voltage-gated ions close
  • stops Na moving in
  • K moves out
58
Q

what are the 5 changes in membrane potential as an impulse is passed along a neuron?

A
  • resting potential
  • depolarisation
  • action potential
  • repolarisation
  • hyperpolarisation

AH Biology (10 decks)

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