Chapter 3- 3.11- ATP Flashcards
What are the three main types of activity cells require energy ?
Synthesis- For example of large molecules such as proteins.
Transport- For example pumping molecules or ions across cell membranes by active transport.
Movement- For example protein fibres in muscle cells that cause muscle contractions.
What does ATP stand for?
Adenosine triphosphate.
Inside the cell they are able to supply this energy in such a way that it can be used.
What is an ATP molecule composed of?
Nitrogenous base, a pentose sugar and tree phosphate groups. It is a nucleotide.
ATP is very similar to that of nucleotides involved in the structure of DNA and RNA. However in ATP the base is always adenine and there are three phosphate groups instead of one.
The sugar in ATP is ribose, as in RNA nucleotides.
ATP is used for energy transfer in all cells of all living things. Hence it is known as ?
The universal energy currency.
How does ATP release energy?
Energy is needed to break bonds and is released when bonds are formed.
A small amount of energy is needed to break the relatively weak bond holding the last phosphate group in ATP.
However, a large amount of energy is then released when the liberated phosphate undergoes other reactions involving bond formation.
Overall a lot more energy is released than used, approximately 30.6 KJmol^-1.
The release of energy from ATP involves water when the phosphate group is removed. Therefore this is an example of a ?
Hydrolysis reaction.
ATP + H2O -> ADP + P(1) + ENERGY
Adenosine triphosphate + water -> adenosine diphosphate + inorganic phosphate + energy.
Does the hydrolysis of ATP occur in isolation?
No, but in association with energy-requiring reactions. The reactions are said to be “coupled” as they happen simultaneously.
ATP is hydrolysed into adenosine diphoshate (ADP) and a phosphate ion, releasing energy.
Why Is ATP not a good long term energy store?
The instability of the phosphate bond in ATP means that it is not a good long-term energy store.
Fats and carbohydrates are much better for this.
The energy released in the breakdown of these molecules (process called cellular respiration) is used to create ATP. This occurs by reattaching a phosphate group to an ADP molecule. This process is called phosphorylation.
As water is removed in this process it is an example of a condensation reaction.
Why is ATP a good immediate energy store?
Due to the instability of ATP, cells do not store large amounts of it. However, ATP is rapidly reformed by the phosphorylation of ADP. This interconversion of ATP and ADP is happening constantly in all living cells, meaning cells do not need a large store of ATP. Therefore making it a good immediate energy store.
What are the properties of ATP?
- Small, moves easily into, out of and within cells.
- Water soluble, energy-requiring processes happen in aqueous environments.
- Contains bonds between phosphate with intermediate energy: large enough to be useful for cellular reactions but not so large that energy is wasted as heat.
- Releases energy in small quantities, quantities are suitable to most cellular needs, so that energy is not wasted as heat.
- Easily regenerated, can be recharged with energy.
