proteins Flashcards

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1
Q

what is a chain of amino acids called

A

a polypeptide chain

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2
Q

what is the structure of an amino acid

A

carbon (C) attached to an amine (NH3), a carboxyl (COOH), and an R group (varient)

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3
Q

how many different R groups/amino acids are there

A

20

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4
Q

what bonds are in a polypeptide

A

peptide bonds

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5
Q

where do the peptide bonds form

A

between N in amine group and C in carboxyl group

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6
Q

what type of reaction forms a dipeptide

A

condensation

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7
Q

what does a condensation reaction produce

A

H20

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8
Q

what is the primary structure

A

sequence of amino acids in a polypeptide chain

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9
Q

what can a change in the polypeptide amino sequence cause

A

may cause a change in the protein shape and may stop it from carrying out its function

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10
Q

what is the secondary structure

A

either an alpha helix or a beta pleated sheet

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11
Q

how does the secondary structure form

A

H of the amine group has overall positive charge
O of the carboxyl group has overall negative charge
hydrogen bonds can form between these 2 groups
causes the chain to be twisted into a 3D shape

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12
Q

what bonds form the tertiary structure

A

hydrogen bonds
ionic bonds
disulphide bridges

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13
Q

where do the tertiary structure bond forms

A

only between the R groups

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14
Q

what is the relative strength of hydrogen bonds

A

weak

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15
Q

what is the relative strength of disulphide bridges

A

very strong

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16
Q

what are the features of ionic bonds (2)

A

strong and vulnerable to pH

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17
Q

what is the purpose of the 3D tertiary structure

A

makes each protein distinctive and allows it to recognise and be recognised by other molecules.

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18
Q

what feature defines a protein having a quaternary structure

A

protein has more than one polypeptide chain

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19
Q

what are the 2 molecular shapes of proteins

A

fibrous or globular

20
Q

fibrous vs globular stability

A

fibrous stable
globular not stable

21
Q

fibrous vs globular bonds

A

fibrous mainly H bonds
globular many types of bonds

22
Q

fibrous vs globular shape

A

fibrous long and linear
globular coiled with depressions

23
Q

fibrous vs globular sequence

A

fibrous regular sequence
globular irregular sequence

24
Q

fibrous vs globular function

A

fibrous structural function
globular metabollic function

25
Q

fibrous vs globular solubility

A

fibrous insoluble
globular soluble

26
Q

what is biuret solution made of

A

sodium hydroxide and copper (II) sulphate solution

27
Q

what colour is biuret solution originally

A

blue

28
Q

what colour is biuret solution in the presence of protein

A

purple

29
Q

what type of protein is an enzyme (2)

A

globular
tertiary structure

30
Q

how is an enzyme substrate complex held together

A

weak non covalent interactions (H, ionic, hydrophobic)

31
Q

how do enzymes lower the activation energy of a reaction (2)

A

put stress on the bonds within a molecule
hold molecules closer together

32
Q

what is the lock and key model

A

each substrate will only fit the active site of one particular enzyme

33
Q

what is the induced fit model

A

suggests the active site is flexible, the substrate doesn’t only have to fit the active site, it also has to make the active site change in the right way.

34
Q

how does increasing temperature affect enzyme action

A

increasing temperature means more heat energy so more kinetic energy for enzyme and substrate.
move faster so more collisions.
more ES complexes formed.
rate of reaction is increased.

35
Q

how does too high temperature affect enzyme action

A

too high temperature means more kinetic energy.
enzyme molecules vibrate more, H bonds in tertiary structure break.
changes shape of enzyme.
active site changes shape so substrate cannot fit.

36
Q

how does optimum pH affect enzyme action

A

solution of optimum pH has H ions, does not disrupt ionic bonding.
no change in shape of enzyme, no change in active site, ES complexes formed, rate of reaction is maximum.

37
Q

how does pH being too high or low affect enzyme action

A

ionic bonds in tertiary structure break, changes shape of enzyme, ES complexes not formed, rate is reduced.

38
Q

how does substrate concentration affect enzyme action

A

substrate concentration increasing means more chance of enzymes and substrates colliding.
more ES complexes formed.
increases rate of reaction.

39
Q

why is substrate concentration limiting

A

eventually all enzyme active sites are occupied, enzymes are working at maximum turnover rate.

40
Q

how does increasing enzyme concentration affect enzyme action

A

more enzymes so more active sites
more ES complexes formed
more products formed

41
Q

what are the two types of enzyme inhibitors

A

competitive and non competitive

42
Q

where do competitive inhibitors bind

A

the active site

43
Q

limitation of competitive enzymes

A

when the inhibitor leaves the active site, substrates can then bind

44
Q

where do non competitive inhibitors bind

A

to the allosteric site

45
Q

what do non competitive inhibitors do

A

attach to allosteric site
changes shape of the active site so further substrate molecules cannot enter and form ES complexes