Unit 1-Metabolic Pathways Flashcards
What are metabolic pathways?
Metabolic pathways are enzyme-catalysed reactions within a cell.
All of the metabolic pathways in an organism
Metabolism
What are the two types of metabolic pathways?
Anabolic and catabolic.
What is cell metabolism?
The collective term for all the biochemical reactions that occur in a living cell.
What do anabolic reactions do?
Anabolic reactions build up molecules from small molecules and requires energy.
What do catabolic reaction do?
Catabolic reactions break down large molecules into smaller molecules and release energy.
In a metabolic pathway, what controls each step?
Enzymes.
What are enzymes?
Biological catalysts which speed up chemical reactions within living things.
What are enzymes that work inside a cell?
Intracellular enzymes.
What are enzymes that work outside a cell?
Extracellular enzymes (pepsin in the stomach).
During a chemical reaction, what is energy needed for?
Energy is needed to break chemical bonds during a chemical reaction.
What is the energy needed to break the chemical bonds in a chemical reaction called?
The activation energy.
What do enzymes do to the activation energy needed for a reaction to proceed?
Enzymes lower/decrease the activation energy
What is the region of an enzyme which allows the substrate to bind?
Active Site
What is induced fit?
Induced fit is when the active site can change shape slightly when it comes in contact with a substrate molecule for a better fit.
What does affinity mean?
An attraction for something.
If a substrate has a high affinity for the active site, what does the active site do?
The active site works by holding the reactants together together in an induced fit.
This acts to weaken the chemical bonds in the reactants.
This allows the reaction to take place.
Once the reaction has taken place, what happens to the products?
Since the products have a low affinity for the active site, they are released.
What can enzyme activity be affected by?
Temperature.
pH.
Substrate concentration.
Concentration of product.
Inhibitors.
As the concentration of a substrate increases, what also increases?
The reaction rate.
All of the enzyme’s active sites have become occupied with substrates, what is now the limiting factor?
Enzyme concentration.
When all of the enzymes are occupied by substrates what is this called?
The point of saturation.
What is an inhibitor?
An inhibitor is a substance that decreases the rate of an enzyme-controlled reaction.
What are the three types of inhibition?
Competitive inhibition
Non-competitive inhibition
Feedback inhibition
Competitive inhibition
Inhibitor molecule binds to the active site of the enzyme and stops the substrate from binding
What property of a competitive inhibitor allows it to compete with the substrate?
They have a similar molecular shape allowing them to bind to the enzyme’s active sites.
How can competitive inhibition be reversed?
By increasing substrate concentration.
Non-competitive inhibition
Inhibitor does not bind to the active site but does bind to a different part of the enzyme and changes the active site shape.
Will increasing substrate concentration reverse non-competitive inhibition?
No
Feedback inhibition
End product in a metabolic pathway binds to an enzyme at the start of the pathway stopping metabolic pathway
