biological molecules proteins (KRJ)

Question 1

what is the primary structure

Answer 1

the sequence of amino acids which determins the properties of the protein
peptide bonds only

Question 2

what is the secondary structure

Answer 2

this is formed by the helical coiling and pleating of the polypeptide chain
large number of weak hydrogen bonds

Question 3

what are the secondary structure

Answer 3

folding of the alpha helix and the beta pleated sheets produces a unique 3D shape
disulphide , ionic, hydrogen bonds and van der Waals forces

Question 4

what is the quaternary structure

Answer 4

proteins that have more than 1 poly peptide chains e.g., haemoglobin

Question 5

what is an amino acid made from

Answer 5

an amine group
a COOH group
a R group

Question 6

what bonds form proteins

Answer 6

peptide bonds

Question 7

what are the types of proteins

Answer 7

2 dipeptide
3 tripeptide
4+ polypeptide

Question 8

how is a peptide bond formed between amino acids

Answer 8

a condensation reaction between the amine group and the COOH group of another

Question 9

how can proteins have the same number and types of amino acids but have different structures

Answer 9

the order of bases are different in the primary structure resulting in different shapes as beta pleated sheets and alpha helix in different places

Question 10

what are the factors affecting enzyme activity

Answer 10

temperature
PH
substrate concentration
competitive inhibitors
non competitive inhibitors

Question 11

describe the effect temperature has on enzyme activity

Answer 11

at the temperature increases (0-40), the enzyme activity steadily increases until the the peak, however as the temp increases (40-70) enzyme activity decreases

Question 12

explain the effect temperature has on enzyme activity

Answer 12

as temperature increases so does enzyme activity (0-40) as there is more kinetic energy so there is more collisions between the active sites and substrates creating more ES complex, however as temperature increases (40-70) the bonds in the tertiary structure are broken which changes shape of the active site so the substrate can no longer fit so less ES complex

Question 13

describe the effect PH has on enzyme activity

Answer 13

as you increase or decrease the pH from the optimum the enzyme activity rapidly decreases

Question 14

explain the effect PH has on enzyme activity

Answer 14

in different PH from the optimum the ionic bonds of the tertiary structure break changing the shape of the active site, the active site is no longer complementary so less ES complexes form

Question 15

describe the effect substrate concentration has on enzyme activity

Answer 15

as the substrate concentration increases so does the ROR steadily until the optimum conc, after this the ROR is constant

Question 16

explain the effect substrate concentration has on enzyme activity

Answer 16

more substrates mean more ES complexes form as the maximum ROR is reached all enzyme active sites are full with substrate molecules. after optimum the substrate conc is not the limiting factor

Question 17

what are competitive inhibitors

Answer 17

have a similar molecular shape to the substrate
compete with substrate for the active site
the inhibitor fits into the active site
so less substrates bind
so less ES complexes for reducing the ROR

Question 18

what are non competitive inhibitors

Answer 18

have a different shape to the substrate
they bind to the allosteric site
this changes the shape of the active site
they effectively reduce the amount of active sites so reduce ROR as less ES complexes form

Question 19

what is an enzyme

Answer 19

they are protein catalysts that lower the activation energy through the formation of enzyme substrate complexes

Question 20

what are the characteristics of enzymes

Answer 20

• they are highly specific, only complementary
  substrates can bind
• globular, roughly spherical in shape
  -remain unchanged, not used up in reaction

Question 21

what is the lock and key hypothesis

Answer 21

substrate is complementary to active site
shows that enzymes are specific
they have specially shaped active sites only complementary substrate can fit in