Importance of ATP

Question	Answer
ATP- what is it	Universal energy currency- used in all cells to drive their reactions-ATP is made when energy becomes available eg in respiration and in the light dependent reactions of photosynthesis- is broken down when cell needs energy eg in muscle contraction and powering membrane Na+ and K+ pumps
Why is ATP suited to its role	-its inert -can pass out of mitochondria into the cytoplasm - releases energy efficiently -releases energy in useable quantities- little wasted as heat - is easily hydrolysed to release energy - is readily reformed by phosphorylation
Chemiosmosis- WJEC definition	The flow of protons down an electrochemical gradient through ATP synthetase, coupled w/ the synthesis of ATP from ADP and a phosphate ion
Chemiosmosis- pt1	In the synthesis of ATP, electrons and protons, derived from hydrogen atoms have different pathways - Electrons from hydrogen atoms are transferred from a donor molecule to a recipient- then a sequence of reactions transfers the electrons from one molecule to the next- each transfer= redox reaction- oxidation reactions makes energy available- energy eventually used to synthesise ATP
Importance of oxidation in chemiosmosis	Energy released by oxidisation pumps protons from hydrogen atoms across a membrane- more concentrated on one side of membrane than the other- difference in concentration of the protons and the charge on either side of the membrane creates an electrochemical gradient
Importance of oxidation in chemiosmosis pt2	source of potential energy- protons flow back down gradient in process called chemiosmosis through enzyme ATP synthetase- energy they release as they do so- converted into chemical energy in ATP.,
The mitochondria and chloroplast membranes	ATP synthetase makes ATP from energy associated with proton gradients across membranes- Respiration uses inner membranes of mitochondria- photosynthesis uses thylakoid membranes of chloroplast- bacteria do not have internal membranes- use cell membranes to establish proton gradient by pumping protons out of cytoplasm, into space between cell membrane and peptidoglycan layer
Endosymbiosis	Common function of the inner membranes of mitochondria, chloroplasts and bacteria supports theory of endosymbiosis-membranes must only let protons through and in a highly controlled way- protons= tiny/ easily pass through water molecules- so membranes must also be water tight- described as sealed membranes
diagrams of mitochondrion and chloroplast	p13
Proton gradient- origin of life	Proton gradients occur in non living systems- naturally occuring events like these may have had great impact on origin of life as proton gradients is fundamental for all living things
Proton gradients- photosynthesis	The chemiosmosis on thylakoid membranes takes place during the light-dependent reactions. During this process, photoexcited electrons move through the photosystems. It involves the following steps; * The photons of light fall on the photosystems and excite the electrons. * The photoexcited electrons move through the electron transport chain. * As the electrons move down the electron transport chain, energy is liberated that is used to pump hydrogen ions from the stroma of chloroplasts into the lumen of the thylakoids.
Proton gradients- photosynthesis- pt2	The energy of electrons is stored in the form of electrochemical gradient of protons across thylakoid membrane Protons move down conc gradient back down into stroma- passes via ATP synthase- creates energy Used to phosphorylate ADP in stroma NADP= final electron acceptor
Proton gradients- respiration	Electrons= excited by energy derived from food molecules- whole process happens- energy released by chemiosmosis as protons flow back into matrix by ATP synthetase incorporated into ATP- energy not incorporated is lost as heat
Disrupting proton gradients causes death pt 1	Apoptosis= programmed cell death- occurs eg when fingers and toes grow in embryonic development- operates by preventing proton gradients from forming-
pt2- why is DNP fatal	DNP can cross this membrane on it's own. DNP can also grab a proton and carry the proton across the membrane. When this happens, you have a shortage of protons for ATP synthase which results in a shortage of ATP. Your body then needs to continue to burn more carbs, fat, and protein at a higher rate to make up for the shortage of ATP. When DNP transports a proton across the membrane heat is produced. (all energy released from those molecules= converted to heat- body overheats sometimes fatally
Electron transport chain	=Series of protein carriers on the inner membrane of mitochondria and chloroplasts - releases energy from electrons- incorporates it into ATP Hydrogen atoms derived from respiratory breakdown of glucose are transferred by dehydrogenase enzymes to co- enzymes NAD and FAD- carried to inner membrane of mitochondrion- electrons and protons have different paths but both move through electron transport chain- so system often described as transferring hydrogen atoms
Electron transport chain pt2	For every 2 protons delivered by reduced NAD, enough energy is released to synthesise 3 molecules of ATP-for every 2 protons delivered by FAD- only enough for 2 molecules of ATP- Energy for proton pump and electron transport chain comes from oxidation reactions= addition of phosphate group- happens to ADP when using this energy- oxidative phosphorylation
Electron transport chain- photosynthesis	In photosynthesis- groups of pigments/ proteins called photosystems transfer excited electrons to electron acceptors and then to a series of proton carriers all on thylakoid membranes- protons from water and the electrons are transferred to coenzyme NADP and subsequently to glycerate- 3- phosphate in path that synthesises carbs- energy that powers proton pump/ electron transport chain comes from light- synthesises ATP by photophosphorylation
Electron transport chain- how ATP synthase works	ATP synthase occurs in all bacteria, arches and eukaryotes- presumably evolved in very early life as protons diffuse down electrochemical gradient through ATP synthase, energy released causes rotor and stalk to rotate-mechanical energy from rotation is converted into chemical energy as a phosphate ion Pi is added to ADP to form ATP in catalytic head- look at diagram p14 to understand
Table-p15	H

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	Created by Darcey Griffiths about 2 months ago