2.1 Metabolic Pathways Flashcards
What are metabolic pathways?
integrated and controlled pathways of enzyme-catalysed reactions within a cell
What 3 different ways can metabolic pathways present themselves?
- reversible
- irreversible
- alternative pathways
What is an anabolic reaction?
build up large molecules from small molecules requiring energy
What is a catabolic reaction?
break down large molecules into smaller molecules and release energy
What 3 proteins can be found in the cell membrane?
-pores->diffusion
-pumps ->active
transport
-enzymes
What are metabolic pathways controlled by?
the presence of absence of particular enzymes and the regulation of the rate of reaction of key enzymes
What is induced fit?
when the active site changes shape to better fit the substrate after the substrate binds, increasing the rate of the reaction
What is the effect of an enzyme on activation energy?
- reduces activation energy
- therefore making it more likely to happen
What affinity do the substrates have for the active site?
high
What affinity does the product have for the active site?
low-allowing them to leave the active site
What is the effect of high substrate concentration on the direction and rate of an enzyme reaction
-as the substrate concentration increases so does the rate of the reaction until a point where all the active sites are occupied and the rate of reaction cannot increase any further (maximum rate of reaction). Reaction keeps going forwards.
What is the effect of low substrate concentration on the direction and rate of an enzyme reaction?
- the reaction rate is low
- as there is not enough substrate to make maximum use of the active sites of the enzymes.
- If the reaction is reversible then it may go backwards
What is competitive inhibition?
- have a similar shape to the substrate and they fit into the active site, but remain unreacted since they have a different structure to the substrate
- less substrate molecules can bind to the enzymes- decreased rate of reaction
- can be reversed by increasing substrate concentration
What is non-competitive inhibition?
- bind to the enzyme but not at the active site
- changes the shape of the active site
- preventing the substrate from binding
- decreasing the reaction rate
- cannot be reversed by increasing substrate concentration
- has a similar effect as decreasing enzyme concentration
What is feedback inhibition?
- happens when the end product in the metabolic pathway reaches critical concentration
- end product inhibits an earlier enzyme, blocking the pathway, preventing further synthesis of the end product
