Biological Molecules - ATP and Water

Question 1

What does ATP stand for and what does it consist of?

Answer 1

• Adenosine triphosphate
• A nucleotide derivative and consists of ribose, adenine and three phosphate groups

Question 2

What is the role of ATP?

Answer 2

• Energy is released when ATP is hydrolysed to form ADP and a phosphate molecule
• This process is catalysed by ATP hydrolase
• The energy comes from the bonds between the phosphate molecules
• These bonds are very unstable and thus have a low activation energy
• The breaking of these is quick and releases a considerable amount of energy

Question 3

What makes ATP a suitable source of energy in cells?

Answer 3

• Releases energy immediately, in one step / single bond broken
• Releases energy in small / manageable amounts
• Can phosphorylate other compounds making them more reactive
• Can be rapidly resynthesised / reformed

Question 4

What are the properties of ATP?

Answer 4

• Bonds between the 3 phosphate groups are unstable
• They have a low activation energy and are easily broken
• When they break, they release energy (≈ 34kJ)
• ATP cannot be stored

Question 5

What are the uses of ATP?

Answer 5

• Metabolic processes
• Movement
• Active Transport
• Secretion
• Activation of molecules

Question 6

What are the properties of water?

Answer 6

• Due to its polar nature, it is a solvent (it allows ionic substances to dissolve by surrounding them)
• It is a solvent due to its polar nature, so metabolic reactions can occur / allows the transport of substances
• It has a high specific heat capacity so buffers changes in temperature (providing stable environments important for aquatic organisms)
• Has a high latent heat of vaporisation so provides a cooling effect through evaporation
• Cohesive because of H bonding so supports columns of water in the xylem of plants / provides surface tension supporting small organisms
• Is a reactive metabolite in condensation / hydrolysis reactions

Question 7

What is the formula and function of iron in water?

Answer 7

• Fe2+
• Plays a role in the transport of oxygen in haemoglobin

Question 8

What is the formula and function of phosphate in water?

Answer 8

• PO(4)3-
• Structural role in DNA, role in energy storage in ATP and role in plasma membrane in phospholipids

Question 9

What is the formula and function of hydrogen in water?

Answer 9

• H+
• Determines the pH of solutions and affects enzyme action

Question 10

What is the formula and function of sodium in water?

Answer 10

• Na+
• Role in the co-transport of glucose and amino acids
• Role in resting potential and action potential in neurones