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Biochemistry /Biology IB HL - 8.1 Metabolism Part 3

Biology IB HL - 8.1 Metabolism Part 3

Biochemistry20 CardsCreated 9 days ago

This deck covers key concepts related to metabolism, including cyanide's effect on cytochrome oxidase, end-product inhibition, isoleucine synthesis, and enzyme-catalyzed reactions.

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Why is cyanide binding to cytochrome oxidase harmful?

By changing the shape of the active site, cytochrome oxidase can no longer pass electrons to the final acceptor (oxygen)
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Key Terms

Term
Definition
Why is cyanide binding to cytochrome oxidase harmful?
By changing the shape of the active site, cytochrome oxidase can no longer pass electrons to the final acceptor (oxygen)
What is the final result of cyanide binding?
Consequently, the electron transport chain cannot continue to function and ATP is not produced via aerobic respiration
What is end-product inhibition?
End-product inhibition (or feedback inhibition) is a form of negative feedback by which metabolic pathways can be controlled
What is the inhibitor in end-product inhibition?
In end-product inhibition, the final product in a series of reactions inhibits an enzyme from an earlier step in the sequence
Where the end-product bind to in end-product inhibition?
The product binds to an allosteric site and temporarily inactivates the enzyme (via non-competitive inhibition)
What is the end result of end-product inhibition?
As the enzyme can no longer function, the reaction sequence is halted and the rate of product formation is decreased
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Biology IB HL - 8.1 Metabolism Part 3
TermDefinition
Why is cyanide binding to cytochrome oxidase harmful?
By changing the shape of the active site, cytochrome oxidase can no longer pass electrons to the final acceptor (oxygen)
What is the final result of cyanide binding?
Consequently, the electron transport chain cannot continue to function and ATP is not produced via aerobic respiration
What is end-product inhibition?
End-product inhibition (or feedback inhibition) is a form of negative feedback by which metabolic pathways can be controlled
What is the inhibitor in end-product inhibition?
In end-product inhibition, the final product in a series of reactions inhibits an enzyme from an earlier step in the sequence
Where the end-product bind to in end-product inhibition?
The product binds to an allosteric site and temporarily inactivates the enzyme (via non-competitive inhibition)
What is the end result of end-product inhibition?
As the enzyme can no longer function, the reaction sequence is halted and the rate of product formation is decreased
What is the purpose of end-product inhibition?
End-product inhibition functions to ensure levels of an essential product are always tightly regulated
What happens if product levels build up?
If product levels build up, the product inhibits the reaction pathway and hence decreases the rate of further product formation
What happens if product levels drop?
If product levels drop, the reaction pathway will proceed unhindered and the rate of product formation will increase
What is isoleucine?
Isoleucine is an essential amino acid, meaning it is not synthesised by the body in humans (and hence must be ingested)
What are food sources rich in isoleucine?
Food sources rich in isoleucine include eggs, seaweed, fish, cheese, chicken and lamb
How may isoleucine be synthesised in plants and bacteria?
In plants and bacteria, isoleucine may be synthesised from threonine in a five-step reaction pathway
What is the first step in isoleucine synthesis?
In the first step of this process, threonine is converted into an intermediate compound by an enzyme (threonine deaminase)
What can isoleucine bind to?
Isoleucine can bind to an allosteric site on this enzyme and function as a non-competitive inhibitor
What is isoleucine synthesis an example of?
As excess production of isoleucine inhibits further synthesis, it functions as an example of end-product inhibition
What is the purpose of end-product inhibition for isoleucine?
This feedback inhibition ensures that isoleucine production does not cannibalise available stocks of threonine
How can enzyme-catalysed reactions be calculated?
The rate of an enzyme-catalysed reaction can be calculated and plotted according to the time taken for the reaction to proceed
How can the time taken for an enzyme to catalyse a reaction be measured?
The time taken can be measured according to either the amount of product formed or the amount of substrate consumed
What is reaction rate the inverse of?
reaction rate is the inverse of time taken, meaning that the reaction rate is higher when less time is taken (and vice versa)
What formula can be used to calculate the rate of reaction?
The rate of reaction can be calculated according to the following formula: Rate of reaction (s–1) = 1 / time taken (s)