3.1 ATP

Question 1

Why is ATP suited to its role?

Answer 1

• inert
• able to move mitochondria—>cytoplasm
• release energy efficiently
• release energy in suitable quantities
• easily hydrolysed
• readily reformed by phosphorylation

Question 2

Define chemiosmosis

Answer 2

• flow of protons down an electrochemical gradient through ATP synthesise coupled with the synthesis of ATP from ADP and a phosphate ion

Question 3

Electron pathway in chemiosmosis

Answer 3

• transferred from a donor molecule to a recipient
• sequence of reactions transfers the electrons from one molecule to the next
• each transfer is redox
• oxidation makes energy available and this energy is used to synthesise ATP

Question 4

Proton pathway in chemiosmosis

Answer 4

• energy released by oxidation pumps the protons from the hydrogen atoms across a membrane so that they are more concentrated on one side of the membrane than the other
• diff in conc and charge constitutes an electrochemical gradient and is an energy source
• protons flow down gradient through ATP synthetase
• energy converted to chemical energy in ATP

Question 5

Result of discounting proton gradients

Answer 5

• death
• apoptosis - programmed cell death which occurs when fingers and toes form in embryonic development - prevent proton gradients across cell membranes from forming
• DNP (mitochondrial poison) allows electron transport but not ATP synthesis

Question 6

Describe the position of the high energy bond of ATP

Answer 6

• the bond between the terminal phosphate groups on ATP

Question 7

Why is substrate level phosphorylation referred to as the simplest way to make ATP?

Answer 7

• does not involve ETC, electrochemical gradient or oxygen

Question 8

Explain how energy from electrons across ETC is used to produce ATP

Answer 8

• as electrons pass along ETC energy is released to pump protons into inter-membrane space
• creates electrochemical gradient for protons to flow down ATP synthetase
• ADP + Pi —> ATP

Question 9

Explain symptoms of DNP

Answer 9

• use of fat stores as an energy source causes weight loss
• increased metabolic rate to compensate for ATP underproduction
• lack of ATP causes fatigue
• heat produced as byproduct which increases body temp
• more sweat to lower body temp

Question 10

Explain importance of ATP in cells

Answer 10

• protein synthesis, muscle contraction
• only 1 molecule needed
• release small amount when needed
• one enzyme needed to release energy from ATP

Question 11

Why is ATP called the universal energy currency?

Answer 11

• used by all organisms to provide energy for almost all biochemical reactions