Enzymes Flashcards
What is the effect of SUBSTRATE concentration on the rate of enzyme action?
- Low substrate concentration = too few substrate molecules to occupy all the available active sites = low rate of reaction
- Increasing Substrate Concentration increases the rate of reaction. This is because more substrate molecules will be colliding with enzyme molecules, so more product will be formed. all the active sites are occupied at one time
- However, after a certain concentration, any increase will have no effect on the rate of reaction, since Substrate Concentration will no longer be the limiting factor.
The enzymes will effectively become saturated, and will be working at their maximum possible rate.
What is an enzyme inhibitor?
substances that directly or indirectly interfere with the functioning o the active site of an enzyme and so reduce its activity
What are competitive inhibitors (tell me about them)?
- they bind to the active site of the enzyme
- they have a molecular shape similar to that of the substrate, allowing them to occupy the active site of an enzyme
- they compete with the substrate for available active series
Describe how the effect on enzyme activity the competitive inhibitor has is determined?
the difference between the concentration of the inhibitor and the concentration of the substrate determines this :
- if the substrate concentration is increased the effect of the competitive inhibitor is reduced
- Since inhibitors are not permanently bound to the active site when it leaves another molecule can take its place. the concentration of the substrate and the inhibitor depends on this.
- sooner or later, all the substrate molecules will occupy an active site ———> the greater the concentration of inhibitor, the longer this will take
What are non-competitive inhibitors (tell me about them)?
- they bind to the enzyme at a position other than the active site
- when they attach to the enzyme at the binding site, they alter the shape of the enzyme and thus its active site, in such a way that substrate molecules can no longer occupy it and so the enzyme cannot function
What is the definition of metabolism?
the sum of all the biochemical reactions in the body
What is the definition of a metabolic pathway?
a single chain of a biochemical reaction in the body
What does every reaction require to work?
an input of energy (activation energy)
What is the function of RNA?
transfers genetic information from DNA to ribosomes rather than holds information (like DNA)
What are enzymes?
They are globular proteins that act as catalysts to both anabolic (building up) and catabolic (breaking down) reactions. They work both in intracellular and extracellular conditions
What must happen for a chemical reaction to happen?
The enzyme must collide with the substrate with suffient energy
The substrate must fit into the active site
What is the induced fit model?
A
An enzyme-substrate complex forms when the active site changes shape slightly so it is complementary to the substrate
this reduces the activation energy
What is the effect of temperature on enzyme action?
ncrease in temp = increase in kinetic energy= molecules moving around more rapidly and colliding with each other more frequently= more enzyme-substrate complexes= increase in the rate of reaction
Optimum temperature = highest number of collisions and enzyme - substrate complexes
High temperatures to very high temperatures = lots of kinetic energy = Hydrogen bonds holding the 3d structure together breaking = the substrate fits less easily into the active, causing the reaction to slow down = eventually the enzyme doesnt have an active site that fits the substrate anymore- no more enzyme- substrate complexes made due to the enzyme denaturing
What is the effect of pH on enzyme action?
Slight change in pH = slightly alters the charge = harder for enzyme-substrate complexes to form
change in pH = alters the charge on the amino acid that makes up the active site of the enzyme = substrate can no longer become attached o the active site enzyme-substrate complex cannot be formed
change in pH can cause the bonds maintaining the enzyme’s tertiary structure (Hydrogen and ionic bonds) to break.
How is the arrangement of the active site determined?
determined by the hydrogen and ionic bonds between —-NH2 and ——COOH groups of the polypeptides that make up the enzyme. The change in H+ ions affects this bonding, casing the active site to change shape
Draw condensation reaction between two amino acids
Draw the structure of a phosphodiester bond
