2.3 ATP

Explain how DNA polymerase utilises triophosphates in the replication of DNA.

Phosphodiester bonds must be formed between adjacent free activated nucleotide during DNA replication. These activated nucleotides are nucleoside triphoshates. The formation of the phosodiester bonds through condensation reactions helped by DNA polymerase, requires energy which is provides by the hydrolysis of the unstable covalent bonds between the phosphate groups of the activated nucleotide.

Why is ATP a better immediate energy source compared to glucose?

- Each ATP molecule releases less energy as glucose molecules and energy is released in smaller, more manageable amounts. - The hydrolysis of one reaction is easier than a long series so energy is released quicker compared to glucose.

What 5 energy requiring processes are ATP needed for?

- Metabolic processes- supplying energy to make starch from glucose i.e. to use smaller units to build large ones. - Movement - ATP provides energy for muscle contraction, for filaments to slide past one another - Active transport : Provides energy to change shape of plasma protein - Secretion - ATP needed to make lysosomes necessary for the secretion of products. - Activation of molecules, e.g. in glycolysis

Why is ATP not a good long term energy store?

- Unstable phosphate bonds, - Releases smaller amounts .

Synthesis of ATP occurs in 3 ways, Name them.

- in chlorophyll containing plant cells during photosynthesis ( phosphorylation) - Plants and animals in respiration - oxidative phosphorylation - Plant and animal cells, when phosphate groups are transferred from donor molecules to ADP (substrate level phosphorylation) .

What is ATP?

A single molecule of adenosine triphosphate (ATP) is a nucleotide derivative and is formed from a molecule of ribose, a molecule of adenine and three phosphate groups.

How does ATP return?

ATP can be re-synthesisised in a condensation reaction between ADP and Pi. This happens during both respiration and photosynthesis and is catalysed by the enzyme ATP synthase.

Why would cells such as muscle and epithelial cells have lots of mitochondria?

ATP cannot be stored so it has to be continuously made within the mitochondria of cells that need it. Muscle fibres, epithelia cells require energy for active transport, thus needs lots of mitochondria so supply ATP.

Explain with reference in protein shape, how reaction with AtP might cause a channel protein to open or close.

ATP is hydrolysed to form ADP and Pi, releases energy. ADP and Pi have different charge prodiles to AtP so the hydorlusis reacton could cause the channel protein to open or clsoe because ADP and Pi could interact with the ionic bonding in the proteins tertiary structure, affecting its 3D shape.

Explain how ATP can make an enzyme controlled reaction, take place more readily.

Activation of molecules, building up macromolecules, secretion

What can the inorganic phosphate be used for?

The inorganic phosphate released during the hydrolysis of ATP can be used to phosphorylate other compounds, often making them more reactive. This is known as phosphorylation.

What is meant that ATP hydrolysis can be coupled to other energy requiring reactions in the cell?

This means energy can be used directly to make the coupled reaction happen, rather than being lost as heat.

How does ATP store energy?

When energy is needed by a cell, ATP is broken down into ATP, and Pi in a hydrolysis reaction catalysed by ATP hydrolase. A phosphate bond is broken and energy is released. Bonds between phosphate groups are unstable and have low activation energy so when they are broken, energy is released