U1: 6- Metabolic Pathways Flashcards
What name is given to the thousands of biochemical reactions that occur in living cells?
Metabolism
The quantity of energy consumed by an organism per unit time is a measure of what rate?
Metabolic rate
Name two types of metabolic pathway.
Anabolic pathway and catabolic pathway
Which type of metabolic pathway involves the breakdown of complex molecules into simpler ones?
Catabolic
Which type of metabolic pathway involves the build-up of complex molecules from simpler ones?
Anabolic
Which type of metabolic pathway releases energy as it is breaking complex molecules down?
Catabolic
Which type of metabolic pathway requires energy as it builds up small molecules to complex molecules?
Anabolic
In a metabolic pathway what do the two opposing arrows mean?
The reaction is reversible
Metabolic reactions sometimes have places where steps can be bypassed, what are these pathways known as?
Alternative routes
Give three properties of a catalyst.
- lowers the activation energy
- remains unchanged at the end
- increases the rate of reaction
What name is given to biological catalysts?
Enzymes
What state is reached when two reactants have bonds broken and they are in a position that is unstable and ready to form a product?
Transition state
What substance are enzymes made from?
Protein
What name is given to the area on an enzyme that meets with the substrate?
Active site
What determines the shape of the active site?
The sequence of amino acids in the polypeptide that makes up the enzyme molecule
Give the word that is used to describe the fact that one enzyme fits one substrate.
Specific
Give the term that is used to describe the fact that the active site has a strong attraction for the substrate.
High affinity
Once the enzyme has broken the substrate down/built it up and formed the product, how is the attraction for the active site described?
Low affinity
In order for the enzyme’s active site to fit the substrate more closely, the shape of the active site and enzyme change slightly. What is this called?
Induced fit
Fill in the missing gap: The shape of the active site determines the … of reactants.
Orientation
In an enzyme controlled reaction the reaction rate will increase as the substrate concentration increases up until a certain point. After that the rate of reaction does not increase, why is this?
Because all of the active sites on the enzyme are occupied
What can be done to increase the rate of an enzyme controlled reaction once all of the active sites on the enzyme are occupied and substrate has already been increased?
Add more of the enzyme to the reaction
What name is given to a substance that decreases the rate of an enzyme controlled reaction?
An inhibitor
Name two types of inhibitor.
Competitive inhibitor and non-competitive inhibitor
Which inhibitor binds to the active site and competes with the substrate in an enzyme controlled reaction?
Competitive inhibitor
Why is the competitive inhibitor able to join to the active site of an enzyme?
Because it has a similar shape to the substrate
What happens to the rate of reaction in an enzyme controlled reaction that is affected by a competitive inhibitor?
Decreases the rate of reaction but doesn’t stop it altogether because the substrate can still bind sometimes
How could the effects of a competitive inhibitor be reversed?
Increase the substrate concentration
Where does a non-competitive inhibitor bind to?
An allosteric site (site away from the active site)
What does a non-competitive inhibitor do to the shape of an enzyme active site?
Changes the shape of the active site
Why does a reaction affected by a non-competitive inhibitor stop altogether?
Because the shape of the active site has changed permanently and it no longer recognises the substrate
When an end product is made in a metabolic pathway some of the product goes back and inhibits an enzyme at the start of the pathway, what is this called?
End product inhibition
