Chapter 9 Flashcards
what are the advantages of having membrane bound organelles
creates specialised environments for specific functions. increases the number of activities that can occur at the same time in a limited space + under different conditions. Can concentrate reactants and store products
what is an enzyme
organic substance that increases the speed of chemical changes without being altered in the change
what is a catabolic reaction
where complex molecules break down into simpler ones. eg, Breakdown of glucose in respiration
what is a anabolic reaction
where simple molecules join together to form larger, complex molecules. Eg, when amino acids are joined together to form proteins
what are exergonic reactions
Reactions that release energy (exo=out). Seen in catabolic reactions
what are endergonic reactions
reactions that absorb energy (endo=in). Seen in anabolic reactions
what is activation energy
the energy required to initiate a reaction
what is the lock and key model
a model suggesting that the shape of a substrate molecule is an exact fit to the shape of an enzymes active site.
what is the induced fit model
a model to explain that the shape of an enzyme’s active site undergoes specific changes, induced by the substrate to achieve a high degree of specificity with the substrate
what are the five factors that affect enzyme activity
Temperature, pH, Concentration, Inhibitors, Cofactors and coenzymes
how does a change in temperature effect enzyme activity
as the temperature increases, molecules become more active and collide more often. This increase in collisions increases the opportunity for a substrate to bump into its enzyme. the rate of reactions therefore increases. However, if the temperature gets too high the protein will denature. a lower temperature means a lower rate of reaction
how does a change in pH effect enzyme activity
Each enzyme has an optimum pH at which it works. changes in pH may lead to change in shape, denaturation and change in substrate shape
how can substrate and enzyme concentration affect enzyme activity. Draw graph
increasing substrate results in an increase of products until all enzymes are occupied. increasing enzyme results in exponential increase in products until inhibition of enzyme or substrate is depleted
max activity I
I saturation point Rate of reaction I
I
I
I
I
I
I \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
Substrate concentration
what is a competitive inhibitor
substance that competes with a substrate for the enzymes active site
what is a non competitive inhibitor
a molecule that binds to an enzyme at a site other than the active site, this changes shape of the active site so the substrate can no longer bind to it
