Topic 1: Proteins + Enzymes Flashcards
(19 cards)
What are enzymes?
Biological catalysts that don’t get used up, which speed up the reaction by lowering the activation energy.
Explain the induced fit model.
Shape of the active site isn’t exactly complementary to the substrate as the active site changes shape slightly to fit the substrate and form E-S complexes.
What are the 4 factors that affect Enzyme action?
-Enzyme concentration
-Substrate concentration
-Temperature
-pH
How does enzyme concentration affect enzyme action?
Increasing enzyme concentration increases number of active sites, so more E-S complexes are formed.
When would enzyme concentration stop affecting enzyme activity?
Stops increasing as amount of substrate becomes limiting as there’s more enzymes than substrates
How does substrate concentration affect enzyme activity?
Increasing substrate concentration will increase the Rate Of Reaction as there’s more substrate molecules so more successful collisions so more E-S complexes formed.
When does substrate concentrate stop affecting enzyme activity?
RoR slows as enzyme concentration becomes a limiting factor as all the enzymes active sites have been occupied.
How does temperature affect enzyme activity?
As temp increases RoR increases as molecules have more Ke so they move faster.
This increases the number of successful collisions so more E-S complexes formed.
What happens after optimum temperature has been reached and explain why.
-RoR decreases because at high temp enzyme molecules vibrate too much so the bonds holding the tertiary structure are broken.
-Causes active site to change so substrate can no longer bind, so no E-S complexes are formed.
What happens to enzyme activity below and above the optimum pH?
-The H+ ions and OH- ions disrupt the ionic and hydrogen bonds holding the tertiary structure so active site changes.
-The substrate can no longer bind so no E-S complexes formed.
-At extreme pH’s the enzyme denatures
What are competitive inhibitors?
-Inhibitors that have a similar shape to the substrate, so they compete to bind with the active site.
-Block active site so substrates can’t bind to form E-S complexes.
What effect would increasing substrate concentration have on the competitive inhibitors?
- Reduces effect of inhibitor as substrate has more of a chance to bind to the active site to form E-S complexes as the inhibitors are outnumbered.
What are non-competitive inhibitors?
-Inhibitors that have a different shape to the substrate.
-Bind to allosteric site which causes the active site to change shape so its no longer complementary to the substrate, and no E-S complexes formed
What effect would increasing substrate concentration have on non-competitive inhibitors have?
No-effect as the enzymes active site has changed shape so there’s no chance of substrate binding to the active site.
What makes up the general structure of proteins.
Central carbon atom bonded to an Amine group (H2N), a Carboxyl group (COOH), R-group (Variable) and a Hydrogen (H).
What is the proteins Primary structure?
Sequence of amino acids in a polypeptide chain, joined by peptide bonds in a condensation reaction
What is the Proteins secondary structure?
Hydrogen bonds form between amino acids causing the polypeptide chain to coil into an alpha-helix or fold into beta-pleated sheets.
What is the proteins tertiary structure?
3D folding of polypeptide, creating specific shape due to the hydrogen bonds, ionic bonds, and disulphate bridges forming between R groups.
What is the proteins quaternary structure?
More than one polypeptide joining together.
