U2.1 Metabolic pathways Flashcards
Define metabolism.
The total set of reactions in a cell
Define an anabolic reaction.
An energy-requiring reaction which builds up large molecules from small molecules.
Define a catabolic reaction.
An energy-yielding reaction which breaks down large molecules into small molecules.
Name 3 membrane proteins.
Protein pumps, protein pores, and enzymes
Why would a membrane have protein pores?
To allow or restrict the passage of molecules through the membrane (passive process).
Why would a membrane have protein pumps?
To move molecules across the membrane, and they require energy to do this (active process).
Why would a membrane have enzymes embedded in them?
To catalyse specific biochemical reactions.
How can metabolic pathways be controlled by the presence or absence of enzymes?
If enzyme is present reaction pathway may continue, but if enzyme is not present or inhibited, reaction pathway will be stopped.
Describe the induced fit model of enzyme action.
The active site of an enzyme may change shape to better fit the substrate as the substrate binds.
How does the addition of enzymes effect the activation energy of a reaction?
Lowers it.
What is the word used to describe the attraction between enzyme active site and substrate?
High affinity.
Why are products able to leave the active site?
Because they have a low affinity to the active site.
How does substrate concentration effect the rate of reaction?
As the substrate concentration increases, the rate of reaction increases but then becomes constant.
How do competitive inhibitors work?
They bind to the active site of the enzyme, preventing the substrate from binding. This is reversible.
How do non-competitive inhibitors work?
They bind to a separate site (the allosteric site). This changes the shape of the active site and prevents substrates from binding. This is permanent
