3.1 importance of ATP Flashcards
what is adenosine triphosphate (ATP) made from?
- ribose
- adenine
- 3 phosphates
ATP is the universal energy carrier
(used in all reactions in all organisms)
how does ATP release energy?
what enzyme is the reaction catalysed by?
- via a 1 step reaction when the high energy bond between the second and third phosphate group is broken
- this hydrolysis reaction is hydrolysed by the enzyme ATPase
what are some examples of the processes that ATP provides energy for?
- protein synthesis
- muscle contraction
- DNA synthesis
- active transport
- mitosis
chemiosmosis definition
the flow of protons down an electrochemical gradient through ATP synthetase, coupled with the synthesis of ATP from ADP and a phosphate ion
during photosynthesis and respiration, when is ATP made?
- when protons are pumped across the membranes using energy from electrons to create an electrochemical or proton gradient
when does ATP synthetase phosphorylate ADP into ATP?
- when the protons flow back through the stalked particles down the concentration gradient, by a process known as chemiosmosis, ATP synthetase phosphorylates ADP into ATP
(in chloroplasts, this occurs on the thylakoid membranes, whereas in mitochondria, occurs on inner membrane or cristae)
the electrons pass from the proton pumps to a terminal electron acceptor?
what is this in mitochondria? in chloroplasts?
mitochondria : oxygen
chloroplasts : coenzyme NADP or chlorophyll
compare the mechanisms of ATP synthesis in mitochondria and chloroplasts
mitochondria:
- uses energy carried by electrons to pump protons across the membrane, they then flow back through stalked particles
chloroplast:
- uses electron energy to pump protons across the membrane which then flow back through stalked particles
compare the enzyme involved in ATP synthesis in mitochondria and chloroplasts
both ATP synthetase
compare the proton gradient of ATP synthesis in mitochondria and chloroplasts
mitochondria:
- from inter-membrane space to matrix
chloroplast:
- from thylakoid space to stroma
activation energy definition
the minimum amount of energy needed to start a chemical reaction
what is phosphorylation?
the addition of a phosphate group or ion to a molecules
in respiration and photosynthesis, what molecule is most often phosphorylated?
ATP
but other molecules can be phosphorylated as well
what are the 3 types of phosphorylation?
- oxidative phosphorylation
- photophosphorylation
- substrate level phosphorylation
when does oxidative phosphorylation occur?
when a phosphate ion is added to ADP using energy from electron loss
i.e oxidation reaction
what is photophosphorylation?
- the energy that powers the proton pump and electron transport chain in chloroplasts comes from light, hence ATP in chloroplasts is synthesised by photophosphorylation
when does substrate level phosphorylation occur?
when phosphate groups are transferred from donor molecules e.g phosphate is transferred from glycerate-3-phosphate to ADP in glycolysis of respiration
describe how ATP is synthesised
- involves ATP synthase, an enzyme found embedded in cellular membranes
- ATP synthase phosphorylates ADP to form ATP as protons flow through it
compare the flow of protons across the mitochondrial and chloroplast membranes
- mitochondrial membrane : H+ flow from the inter-membrane space into the matrix, across the inner membrane
- chloroplast membrane : H+ flow from the thylakoid space into the stroma, across the thylakoid membrane
how is the proton gradient maintained during chemiosmosis?
- potential energy associated with excited electrons is coupled to the active transport of H+ across the membrane by proton pumps
what is the electron transport chain?
- a series of electron carrier proteins that transfer electrons in a chain of oxidation-reduction reactions, releasing energy
how can dehydrogenase activity be investigated?
- investigated using artificial hydrogen acceptors such as DCPIP, methylene blue and tetrazolium compounds
what colour change is observed when DCPIP is reduced?
dark blue to colourless
