3.11 : ATP Flashcards
What are the three main types of activity that cells require energy for?
Synthesis e.g. Proteins
Transport e.g. Active transport
Movement e.g. Protein fibres in muscle cells that cause muscle contraction
What does ATP stand for?
Adenosine Triphosphate
Describe the structure of ATP
It is composed of :
A nitrogenous base ( adenine )
A pentose sugar ( ribose )
3 phosphate groups
How does ATP release energy?
A small amount of energy is needed to break the relatively weak bond holding the last phosphate group in ATP. However a lot of energy is then released.
As water is involved in the removal of the phosphate group, this is another example of a hydrolysis reaction.
Give the word and symbol equation for the hydrolysis of ATP
ATP + H2O -> ADP + Pi + energy
adenosine triphosphate + water -> adenosine diphosphate + inorganic phosphate + energy
Why is ATP not a good long term energy store? What is a better long term energy store?
Not a good long term energy store because of the instability of the phosphate bonds in ATP.
Fats and carbohydrates are better. The energy released in the breakdown of these molecules ( a 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, this is a condensation reaction.
Why is ATP a good immediate energy store?
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 it is 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 phosphates 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.
