Protein and enzymes

Question 1

draw the structure of an amino acid

Answer 1

-amine group
-r group
-carboxylic acid group
-hydrogen

Question 2

dipeptide

Answer 2

-two amino acids joined
-via a condensation reaction
-joined by a peptide bond

Question 3

primary structure

Answer 3

-the order/number/sequence of amino acids

Question 4

secondary structure

Answer 4

-the way the chain is folded into
-beta pleated cheated
-alpha helical
-held together by hydrogen bonding

Question 5

tertiary structure

Answer 5

-further folding into complex 3D specific structure held together by bonds between R-groups of different amino acids
-HYDROGEN between HO
-IONIC between +/- R groups
-DISULPHIDE bridges
-makes the protein specific to its structure

Question 6

quaternary structure

Answer 6

-two or more polypeptide chains

Question 7

test for proteins

Answer 7

-place sample in a test tube
-add equal volumes of Biuret solution
-colour change to purple shows protein is present

Question 8

Enzyme action and definition

Answer 8

-enzymes are globular proteins which act as biological catalysts
-increase the rate of reaction
-lowering the activation energy
-done by stressing the bonds during the formation of the ESC

Question 9

lock & key model

Answer 9

-active site is rigid and does not change shape
-substrate binds to enzymes active site
-substrate fits exactly to the complementary active site
-products are formed so are released as no longer fit the active site
-enzyme free to take part in another reaction

Question 10

induced fit model

Answer 10

-active site not complementary
-active site changes shape as the substrate binds
-so stressed the substrate bonds to lower the Ea of the reaction
-active site returns to its original shape

Question 11

effect of temperature on ROR

Answer 11

-increase in temp
-increase in kinetic energy
-more successful collisions
- more ESC form per second
-denaturation: past the optimum the hydrogen/ionic bonds will break causing a change in tertiary structure causing a change in the active site
-active site is no longer complementary so less ESC

Question 12

effect of pH

Answer 12

-enzymes have an optimal pH
-if made more acidic or more basic
-charge on R groups are changed
-ionic bonds are broken
-tertiary structure is changed
-active site changes shape
-no longer complementary
-less ESC formed

Question 13

effect of substrate conc. on graph

Answer 13

-increases
-plateaus
-as enzyme becomes the limiting factor

Question 14

effect of enzyme conc. on graph

Answer 14

-increases
-plateaus
-as substrate becomes the limiting factor

Question 15

competitive inhibitors

Answer 15

-similar shape to substrate
-binds to active site
-less ESC
-less product formed

Question 16

non-competitive inhibitor

Answer 16

-not a similar shape to the substrate
-inhibitor binds to the allosteric site
-changes the shape of the active site
-less ESC
-less product formed

Question 17

activation energy

Answer 17

minimum energy required for a successful chemical reaction