96 WJEC Biology AS Level - Marianne Izen - 2nd Edition (Nucleic Acids And Their Functions) Flashcards
What is ATP?
What do the initials stand for?
ATP is a nucleotide.
The initials stand for adenosine triphosphate.
This indicates that it contains -
1. the base adenine
2. the sugar ribose
3. three phosphate groups.
What happens to ATP when energy is needed ?
When energy is needed in living organisms:
- The enzyme ATPase hydrolyses the bond between the second and third phosphate groups in ATP.
- This removes the third phosphate group, leaving only two.
- The ATP molecule is therefore hydrolysed into adenosine diphosphate (ADP) and an inorganic phosphate ion, with the release of chemical energy.
- Every mole of ATP hydrolysed releases 30.6 kJ when this bond is broken.
- A reaction that releases energy, such as ATP hydrolysis, is an exergonic reaction.
Write the equation for hydrolysis of ATP?
What do the double arrows indicate?
How is ATP formed?
In a condensation reaction catalysed by ATP synthetase, ADP and an inorganic phosphate ion can combine to make ATP and water.
The addition of phosphate to ADP is called phosphorylation.
This requires energy input.
Every mole of ATP synthesised requires 30.6 kJ.
A reaction that requires an energy input, such as ATP synthesis, is an endergonic reaction.
Why do living organisms release energy gradually through respiration?
ATP transfers free energy from energy-rich compounds, like glucose, to cellular reactions, where it is needed.
But energy transfers are inefficient and some energy is always lost as heat.
The uncontrolled release of energy from glucose would produce a temperature increase that would destroy cells.
Instead, living organisms release energy gradually, in a series of small steps called respiration, producing ATP.
Why is ATP called the universal energy currency?
ATP has been called the ‘universal’ energy currency because it is involved in energy changes in all living organisms.
What are the other energy currencies know?
What is their importance?
Other energy currencies are now known, such as phosphocreatine.
The increasing understanding of such molecules provides important information in the field of sports science.
How do you indicate chemical energy in the ATP equation?
As ‘chemical energy’ is not a material, it is not written into the equation.
You can write ‘AH = -30.6 kJ mol” at the end of the equation to indicate a negative heat change, i.e. that the energy is released
Phosphorylation (Key-Term)
The addition of a phosphate group.
Draw the structure of ATP