Topic 2 - How enzymes work Flashcards
what is the activation energy
the energy needed for a reaction to get started
what is a substrate
a molecule on which an enzyme acts
what is the lock-and-key hypothesis
a model that explains enzyme actions by an active site in the protein structure that has a specific shape. The enzyme and substrate slot together to form a complex as a key fits in a lock
what is an active site
the area of an enzyme that has a specific shape into which the substrates of a reaction fit
what is the induced-fit hypothesis
a model for enzyme action where the active site is considered to have a more flexible shape. Once the substrate fits the active site, the shape of the site is changed around it to form the active complex. Once the products have left the complex, the enzyme reverts to its inactive, relaxed form
what is the initial rate of reaction
the measure taken to compare the rates of enzyme controlled reactions under different conditions
what is the molecular activity
the number of substrate molecules transformed per minute by a single enzyme molecule
what is the temperature coefficient (Q10)
the measure of the effect of temperature on the rate of a reaction
what do enzymes do in terms of activation energy
lower the activation energy for a reaction to take place
how does an enzyme do with the substrate
the formation of the enzyme/substrate complex lowers the activation energy of the reaction. The active site affects the bonds in the substrate, making it easier for them to break, and the reacting substances are brought close together, making it easier for bonds to form between them
why is the induced-fit hypothesis better than the lock-and-key hypothesis
the lock-and-key hypothesis is over-simplified
what is important to do in an experiment including enzyme
to provide a large excess of substrate in enzyme experiments
state 5 factors of rate of reaction of enzymes
- concentration fo an enzyme
- if an enzyme catalyses a specific reaction or groups of reactions
- number of substrate molecules present
- temperature
- pH
what is the formula for temperature coefficient (Q10)
rate of reaction (x+10) °C/ rate of reaction at x °C
how does pH affect enzyme activity
pH affects the shape of the proteins, as it affects the interactions between the R groups
