✅3.1 -the Importance of ATP

Question 1

What is ATP described as?

What does this mean?

Answer 1

Universal energy currency

It is used in all cells to drive their reactions and is characteristic Of all living systems

Question 2

Name two chemical reactions which produce ATP

Answer 2

Respiration and photosynthesis

Question 3

Give some examples of when the cell breaks down ATP to energy

Answer 3

In biosynthesis, muscle contractions and powering Na+/K+ pumps

Question 4

What can we infer by the fact that ATP was present in all living systems?

Answer 4

It was probs present in LUCA (last universal common ancestor of all cells)

Question 5

Why is ATP suited to its role? (6)

Answer 5

• it’s inert
• can pass out of mitochondria into the cytoplasm
• releases energy efficiently
• releases energy in useable quantities so little is wasted as heat
• easily hydrolysed to release energy
• readily formed by phosphorylation

Question 6

Define chemiosmosis

Answer 6

The flow of protons down an electrochemical gradient, through ATP synthetase, coupled with the synthesis of ATP from ADP and a phosphate ion

Question 7

Describe the pathway of electrons to allow chemiosmosis to occur (3)

Answer 7

1) Electrons from hydrogen atoms are transferred from a donor molecule to a recipient
2) sequence of redox reactions occur (molecule looses electron =oxidised, molecule gains an electron =reduced)
3) oxidation reactions make energy available and energy is used to synthesise ATP

Question 8

Describe the pathway of protons to allow chemiosmosis to occur (4)

Answer 8

1) energy released by oxidation pumps the protons from Hydrogen atoms across a membrane via active transport (phospholipid bilayer)
2) difference in concentration creates an electrochemical gradient which is a source of potential energy
3) protons diffuse down this gradient through the stalked particle, through the enzyme ATP synthase which catalyse’s the reaction ADP+P+energy—> ATP
4) energy they release is converted into chemical energy in ATP

Question 9

Main Bacteria adaption for chemiosmosis

Answer 9

They don’t have internal membranes and :: use cell membrane to establish proton gradient by pumping protons out into the cell wall

Question 10

Describe chemiosmosis in chloroplast (5)

Answer 10

1) electrons are excited by energy from light
2) elections diffuse through carriers in the membrane in the thylakoid membranes
3) energy pumps protons (AT) from the stroma into spaces between thylakoids membranes
4) protons diffuse back down electrochemical gradient into stroma through ATP synthase (equation)
5) energy incorporated into ATP

Question 11

What does ATP do in plant cell?

What does energy do in a plant cell?

Answer 11

ATP drives light-independent reactions of photosynthesis

Energy is incorporated into macromolecules made by the cell

Question 12

Describe the process of chemiosmosis in the mitochondria

Answer 12

1) in respiration electrons are excited by energy derived from food molecules
2) diffuse through a series of carriers on the inner membrane
3) energy pumps protons (AT) across the membrane from the matrix into the inter membrane space producing electrochemical gradient
4) protons diffuse back down gradient through the stalled particle and ATPsynthase
5) energy incorporated into ATP or lost as heat

Question 13

Which membrane is used in chemiosmosis in the mitochondria?

Answer 13

Inner membrane of mitochondria called the Cristae

Question 14

Which membrane is used in chemiosmosis in the chloroplast?

Answer 14

Photosynthesis used thylakoid membranes (independent from the inner membrane of the chloroplast)

Question 15

Why does the Cristae, thylakoid and bacteria cell membrane have to be sealed?

Answer 15

Protons are very small and hence easily pass through the membrane via water molecules if they weren’t water tight

Question 16

What does the common function of the inner membranes of the mitochondria, chloroplasts and bacterial cell membrane support?

Answer 16

Supports endosymbiosis theory

Question 17

What must the cristae, thylakoid and cell membrane of bacterial cells only let through?

Answer 17

Protons, at a highly controlled rate

Question 18

Name two causes of cell death associated with disrupting proton gradients?

Answer 18

1) Apoptosis

2) DNP

Question 19

Describe how apoptosis causes cell death?

Answer 19

It’s a programmed cell death which prevents proton gradients across cell membranes from forming e.g causing cell death during embryonic development

Question 20

What is DNP

Answer 20

DNP is a mitochondrial posion

Question 21

How does DNP cause cell death?

Answer 21

It allows electron transport but does not allow ATP synthesis (uncoupled)
The body oxidises fat and carbohydrates (weightloss) but all the energy releases from those molecules is converted to heat energy (as no ATP can be made)
The body overheats sometimes fatally

Question 22

What is the electron transport chain?

Answer 22

It’s a series of protein carriers on the inner membrane of mitochondria and chloroplasts releasing energy from electrons and incorporating it into ATP.

Question 23

In respiration where are the hydrogen atoms derived from for chemiosmosis?

Answer 23

The respiratory breakdown of glucose

Question 24

Where and by what are the hydrogen atoms transferred in the electron transport chain in the mitochondria?

Answer 24

Hydrogen atoms are transferred by dehydrogenase enzymes to the coenzymes NAD and FAD
They are carried to the cristae of the mitochondria

Question 25

Which is more effiecent coenzyme NAD or FAD and why?

Answer 25

NAD is more efficient as for every two protons delivered by reduced NAD 3 molecules of ATP can be synthesised

For every two protons delivered by reduced FAD enough energy is released for only two ATP molecules

Question 26

What is phosphorylation?

Answer 26

The addition of a phosphate group

Question 27

What is oxidative phosphorylation?

Answer 27

Synthesising ATP by adding a phosphate ion to ADP using energy derived from an oxidation reaction

Question 28

Where is the energy for proton pumps derived from?

Answer 28

Oxidation reactions (loss of electrons)

Question 29

What are photosystems

Answer 29

Groups of pigments and proteins in photosynthesis

Question 30

What do photosystems do in the electron transport chain?

Answer 30

Photosystems transfer excited electrons to electron acceptors and from there to a series of protein carriers all on the thylakoid membranes.

Question 31

What happens in the electron transport chain after the electrons are transported to protein carriers on the thylakoid membrane?

Answer 31

Protons from water and the electrons are transferred to the coenzyme NADP to glycerate phosphate in the pathway that synthesises carbohydrates.

Question 32

Where does the energy that powers the pump and electron transport chain come from in photosynthesis

Answer 32

Comes from light

Question 33

How do chloroplasts synthesise ATP? (Name of process)

Answer 33

Photophosphorylation

Question 34

Where does ATP synthetase occur?

Answer 34

In all Bacteria, Archaea and Eukaryotes

Question 35

Describe the ATP synthetase complex in the mitochondrion

Answer 35

As protons diffuse down their electrochemical gradient through ATP synthase the energy released causes the rotor and stalk to rotate.

Question 36

In the ATP synthetase complex what is the mechanical energy from the rotation converted to?

Answer 36

Mechanical energy—> chemical energy as phosphate ion (P1) is added to ADP to form ATP in the catalytic head

Question 37

How many protons does it take to release 1 ATP molecule

Answer 37

It takes 3 protons to move the rotor 120 degrees releasing 1 ATP molecule