✅3.1 -the Importance of ATP Flashcards
What is ATP described as?
What does this mean?
Universal energy currency
It is used in all cells to drive their reactions and is characteristic Of all living systems
Name two chemical reactions which produce ATP
Respiration and photosynthesis
Give some examples of when the cell breaks down ATP to energy
In biosynthesis, muscle contractions and powering Na+/K+ pumps
What can we infer by the fact that ATP was present in all living systems?
It was probs present in LUCA (last universal common ancestor of all cells)
Why is ATP suited to its role? (6)
- 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
Define chemiosmosis
The flow of protons down an electrochemical gradient, through ATP synthetase, coupled with the synthesis of ATP from ADP and a phosphate ion
Describe the pathway of electrons to allow chemiosmosis to occur (3)
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
Describe the pathway of protons to allow chemiosmosis to occur (4)
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
Main Bacteria adaption for chemiosmosis
They don’t have internal membranes and :: use cell membrane to establish proton gradient by pumping protons out into the cell wall
Describe chemiosmosis in chloroplast (5)
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
What does ATP do in plant cell?
What does energy do in a plant cell?
ATP drives light-independent reactions of photosynthesis
Energy is incorporated into macromolecules made by the cell
Describe the process of chemiosmosis in the mitochondria
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
Which membrane is used in chemiosmosis in the mitochondria?
Inner membrane of mitochondria called the Cristae
Which membrane is used in chemiosmosis in the chloroplast?
Photosynthesis used thylakoid membranes (independent from the inner membrane of the chloroplast)
Why does the Cristae, thylakoid and bacteria cell membrane have to be sealed?
Protons are very small and hence easily pass through the membrane via water molecules if they weren’t water tight
What does the common function of the inner membranes of the mitochondria, chloroplasts and bacterial cell membrane support?
Supports endosymbiosis theory
What must the cristae, thylakoid and cell membrane of bacterial cells only let through?
Protons, at a highly controlled rate
Name two causes of cell death associated with disrupting proton gradients?
1) Apoptosis
2) DNP
Describe how apoptosis causes cell death?
It’s a programmed cell death which prevents proton gradients across cell membranes from forming e.g causing cell death during embryonic development
What is DNP
DNP is a mitochondrial posion
How does DNP cause cell death?
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
What is the electron transport chain?
It’s a series of protein carriers on the inner membrane of mitochondria and chloroplasts releasing energy from electrons and incorporating it into ATP.
In respiration where are the hydrogen atoms derived from for chemiosmosis?
The respiratory breakdown of glucose
Where and by what are the hydrogen atoms transferred in the electron transport chain in the mitochondria?
Hydrogen atoms are transferred by dehydrogenase enzymes to the coenzymes NAD and FAD
They are carried to the cristae of the mitochondria
Which is more effiecent coenzyme NAD or FAD and why?
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
What is phosphorylation?
The addition of a phosphate group
What is oxidative phosphorylation?
Synthesising ATP by adding a phosphate ion to ADP using energy derived from an oxidation reaction
Where is the energy for proton pumps derived from?
Oxidation reactions (loss of electrons)
What are photosystems
Groups of pigments and proteins in photosynthesis
What do photosystems do in the electron transport chain?
Photosystems transfer excited electrons to electron acceptors and from there to a series of protein carriers all on the thylakoid membranes.
What happens in the electron transport chain after the electrons are transported to protein carriers on the thylakoid membrane?
Protons from water and the electrons are transferred to the coenzyme NADP to glycerate phosphate in the pathway that synthesises carbohydrates.
Where does the energy that powers the pump and electron transport chain come from in photosynthesis
Comes from light
How do chloroplasts synthesise ATP? (Name of process)
Photophosphorylation
Where does ATP synthetase occur?
In all Bacteria, Archaea and Eukaryotes
Describe the ATP synthetase complex in the mitochondrion
As protons diffuse down their electrochemical gradient through ATP synthase the energy released causes the rotor and stalk to rotate.
In the ATP synthetase complex what is the mechanical energy from the rotation converted to?
Mechanical energy—> chemical energy as phosphate ion (P1) is added to ADP to form ATP in the catalytic head
How many protons does it take to release 1 ATP molecule
It takes 3 protons to move the rotor 120 degrees releasing 1 ATP molecule
