biological molecules proteins (KRJ) Flashcards
what is the primary structure
the sequence of amino acids which determins the properties of the protein
peptide bonds only
what is the secondary structure
this is formed by the helical coiling and pleating of the polypeptide chain
large number of weak hydrogen bonds
what are the secondary structure
folding of the alpha helix and the beta pleated sheets produces a unique 3D shape
disulphide , ionic, hydrogen bonds and van der Waals forces
what is the quaternary structure
proteins that have more than 1 poly peptide chains e.g., haemoglobin
what is an amino acid made from
an amine group
a COOH group
a R group
what bonds form proteins
peptide bonds
what are the types of proteins
2 dipeptide
3 tripeptide
4+ polypeptide
how is a peptide bond formed between amino acids
a condensation reaction between the amine group and the COOH group of another
how can proteins have the same number and types of amino acids but have different structures
the order of bases are different in the primary structure resulting in different shapes as beta pleated sheets and alpha helix in different places
what are the factors affecting enzyme activity
temperature
PH
substrate concentration
competitive inhibitors
non competitive inhibitors
describe the effect temperature has on enzyme activity
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
explain the effect temperature has on enzyme activity
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
describe the effect PH has on enzyme activity
as you increase or decrease the pH from the optimum the enzyme activity rapidly decreases
explain the effect PH has on enzyme activity
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
describe the effect substrate concentration has on enzyme activity
as the substrate concentration increases so does the ROR steadily until the optimum conc, after this the ROR is constant
explain the effect substrate concentration has on enzyme activity
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
what are competitive inhibitors
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
what are non competitive inhibitors
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
what is an enzyme
they are protein catalysts that lower the activation energy through the formation of enzyme substrate complexes
what are the characteristics of enzymes
- they are highly specific, only complementary
substrates can bind - globular, roughly spherical in shape
-remain unchanged, not used up in reaction
what is the lock and key hypothesis
substrate is complementary to active site
shows that enzymes are specific
they have specially shaped active sites only complementary substrate can fit in
