U2:K1 - Metabolic pathways Flashcards
What are metabolic pathways?
Integrated and controlled pathways of enzyme-catalysed biochemical reactions within a cell
What is a catabolic pathway?
The breakdown of complex molecules to simpler ones, this releases energy
What is an anabolic pathway?
The build up of simple molecules into complex molecules, this requires energy
What are reversible steps?
Steps that allow for alternative routes if there is an excess of substrate
What are irreversible steps?
Steps that are a key regulatory point in the pathway
What are alternative routes?
Routes that allow steps in the pathway to be bypassed
What are plasma membranes of a cell?
The boundary that separates the internal contents from its external surroundings
What does a plasma membrane do?
Regulates the flow of materials into and out of the cell
What are embedded in the membranes?
Protein pores, pumps and enzymes
What is diffusion?
The net movement of molecules or ions from a region of high concentration to low concentration down a concentration gradient
What is active transport?
The movement of molecules across the cell membrane from a low to high concentration, against a concentration gradient
What does active transport require the presence of?
Proteins
How do enzymes lower the activation energy?
By forming an enzyme substrate complex that accelerates the rate of reaction
What does the substrate have a high affinity for?
The active site of the enzyme
What is induced fit?
The active sites flexible structure which changes when the substrate binds
What do enzymes require to function efficiently?
Suitable temperature, appropriate pH, adequate supply of substrate
What is an inhibitor?
A substance which decreases the rate of an enzyme controlled reaction
What can inhibitors do?
Compete for enzyme active sites, change the shape on an active site and inhibit pathways by feedback inhibition
What do competitive inhibitors do?
Bind with the enzymes active site preventing a substrate from binding
What do non-competitive inhibitors do?
Bind with the allosteric site causing a reaction to occur which results in the active site changing shape so the substrate can no longer bind
What happens in feedback inhibition?
The end product binds to enzyme one in metabolic pathways, blocking the pathway, this prevents further synthesis of the end product
