Sean - Introduction Flashcards
Define metabolism
Metabolism is the sum of all the chemical reactions taking place in a cell or organism
What are the two broad categories of biochemical reaction?
Catabolic
Anabolic
What happens in catabolism?
Large molecules are taken apart/broken down into smaller molecules
What happens in anabolism?
Molecules are created - usually small molecules are combined to form a larger molecule
Classify reactions in terms of energy
Exergonic
Endergonic
What is an exergonic reaction?
(3)
A reaction where the reactants have more free energy than the products
It involves a net release of energy and/or an increase in entropy
Occurs spontaneously
How can you identify an exergonic reaction?
There is an increase in entropy
Energy goes out of the reaction - not in
What is an endergonic reaction?
(3)
A reaction whereby the reactants have less free energy than the products
Involves a net input of energy and/or a decrease in entropy
Does not occur spontaneously - energy input is needed
How do you recognise an endergonic reaction?
There will be a decrease in entropy
Energy input is needed
How can reactions power each other?
Exergonic reactions can power endergonic reactions -> coupled reactions
What is the body’s universal energy currency?
Adenosine triphosphate (ATP)
What must be done to ATP to release energy?
ATP must be converted to ADP -> breakage of a high energy bond
What allows exergonic and endergonic reactions to be coupled?
ATP couples these two reactions
Exergonic -> releases ATP
Endergonic -> uses ATP
Give the equation for a coupled reaction (showing the flow of energy)
A+B -> C + D + ENERGY
E + F + ENERGY –> G + H
What are enzymes?
Proteins
Catalysts
Specific for their substrate
Tend to end in ‘ase’
What is a catalyst?
A chemical agent that accelerates a chemical reaction without being consumed/changed in the process
Why are enzymes used in biochemical reactions?
(4)
They speed up the rate of reaction without being consumed in the process
They allows for the conversion of substrate to product (convert nutrients into the cells own molecules)
Utilise and conserve energy by breaking and forming new bonds
Synthesise and degrade biomolecules required for cell function
Classify enzymes
(6)
Oxidoreductases
Transferases
Hydrolases
Lysases
Isomerases
Ligases
Classify enzymes
(6)
Oxidoreductases
Transferases
Hydrolases
Lyases
Isomerases
Ligases
What are oxidoreductases?
Enzymes that catalyse oxidation-reduction reactions (transfer of electrons / H atom reactions)
What are transferases?
Enzymes that catalyse the transfer of functional groups
What are hydrolases?
Enzymes that catalyse hydrolysis reactions (cleavage and introduction of water reactions)
What are lyases?
Enzymes that catalyse the addition of groups to form double bonds or formation of double bonds by removal of groups
What are isomerases?
Enzymes that catalyse isomerization (intramolecular rearrangements)
The transfer of groups within molecules to yield isomeric form
What are ligases?
Enzymes that catalyse the formation of C-C, C-S, C-O and C-N bonds by condensation reactions coupled with ATP breakdown
What bonds are formed by condensation reactions?
(4)
C-C
C-S
C-O
C-N
What is a condensation reaction?
A chemical reaction in which two molecules of functional groups combine to form a larger molecule
How long would it take for DNA to degrade without DNAses?
It would take about 50,000 years
