ATP - Adenosine Triphosphate

Question 1

How is ATP used to release energy?

Answer 1

• energy released from breakdown of organic molecules (glucose and lipids)
• energy from organic molecules is transferred to energy carriers
• most important energy carrier is ATP
• adenosine triphosphate

Question 2

What is ATP?

Answer 2

• a nucleotide
• consisting of adenine, pentose sugar - ribose, 3 phosphate groups
• adenine is an organic nitrogenous base

Question 3

What is adenosine and adenosine diphosphate?

Answer 3

Adenosine - adenine and ribose
Adenosine diphosphate - adenine, ribose and diphosphate

Question 4

What are the properties of the phosphate groups?

Answer 4

• negatively charged so repel each other
• covalent bonds that hold then together unstable (like a coiled spring)
• have a low activation energy and easily broken
• release a large amount of energy

Question 5

What is the reaction to release the terminal phosphate group?

Answer 5

ATP + H2O -> ADP + Pi + 30.6kJ
- hydrolysis reaction
- catalysed by ATP hydrolase

Question 6

What are the properties of the terminal phosphate group removal?

Answer 6

• single step reaction releases a relatively large amount of energy very quickly
• reversible reaction

Question 7

How is ATP synthesised?

Answer 7

• addition of a phosphate group (phosphoric acid)
• called PHOSPHORYLATION of ADP
• wage is removed (condensation reaction)
• catalysed by ATP synthase

Question 8

What is the equation for the synthesis of ATP?

Answer 8

ATP synthase
ADP + Pi + energy ————> ATP + H2O
Reversible reaction symbol

Question 9

Where does the energy to form ATP come from?

Answer 9

• oxidative phosphorylation - oxidation of a respiratory substrate (glucose, lipids) during respiration, most ATP produced is in the mitochondria
• photophorylation - light energy is used to phosphorylate ADP during photosynthesis
• substrate-level phosphorylation - phosphate groups are transferred from a high energy donor molecule to ADP (to make ATP) e.g. creatine phosphate (in muscles)

Question 10

ATP-ADP cycle (ADT + Pi to ATP)

Answer 10

• condensation reaction
• production:
• oxidation of glucose, fatty acids and amino acids (oxidative phosphorylation)
• photophosphorylation - light dependant reaction of photosynethesis
• substrate level phosphorylation, e.g. creatine phosphate broken down to creatine in muscle cells

Question 11

ATP-ADP cycle (ATP to ADT + Pi)

Answer 11

• hydrolysis
• uses:
• muscle contractions
• controlling body temperature e.g. shivering, sweating
• nervous impulses
• secretion
• synthesis of complex organic molecules, e.g. protein synthesis
• active transport
• bioluminescence (producing light energy)

Question 12

What is ATP often know as?

Answer 12

The ‘energy currency of the cell’
- formed by processes like respiration and ‘spent’ on energy requiring processes in cells

Question 13

Why is ATP constantly synthesised and broken down?

Answer 13

• resting human uses 40kg in 24hours
• at any one time body contains 5g of ATP
• constantly synthesised and broken down

Question 14

ATP is useful in many biological processes. Explain why.

Answer 14

• releases energy in small/manageable amounts
• bond broken in one step/ single bond broken / immediate / readily available
• phosphorylation makes it more reactive/ lowers the activation energy
• reformed/ made again/ regeneration

Question 15

Why do humans synthesise more than their body mass everyday?

Answer 15

• constantly synthesising and hydrolysing ATP
• can’t be stored