respiration Flashcards
why plants animals and microorganisms need to respire with ref to active transport and metabolic reactions
all living organisms need a continuous supply of energy to maintain their metabolism so they can do the work necessary to stay alive e.g.:
synthesising complex molecules from smaller ones
active transport of substances across cell membranes agains their concentration gradient
movement of the while oragism by the action of cilia, flagellum or muscles and movement within the organism
maintenance of body temp- especially in mammals, birds, which must release thermal energy to maintain body temp above that of the environment
describe with aid of diagrams the structure of aTp
organic base adenine and the pentose sugar ribose.
together they make nucleoside adenosine
combined with 3 phosphate groups
ATP is therefore an activated mucleotide
what does ATP do
proves immediate source of energy for biological processes
explain the importance of coenzymes in respiration with ref to NAD and coenzyme A
coenzyme A transfers an acetyl group to pyruvate in the krebs cycle and then plays a vital role in respiration. NAD is a hydrogen carrier
where does glycolysis happen
cytoplasm
outline the process of glycolysis beginning with the phosphorylation of glucose to hexose bisphosphate, splitting of hexose bisphosphate into two trios phosphate molecules and further oxidation to pyruvate, producing a small yield of ATP and reduced NAD
(glycolysis- splitting of glucose in the cytoplasm. after many steps glucose is converted into two molecules of pyruvate each with 3 carbon atoms.
energy from ATP is needed in the first two stages, called phosphorylation, but energy that can be used to make ATP is released later on)
a molecule of glucose is phosphorylate, using 2 atp, to give hexose bisphosphate
this converts an energy-rich but unreactive molecule into one that is much more reactive- the chemical potential energy of which can be trapped more efficiently.
the hexose phosphate is plist into two trios phosphate molecules.
hydrogen atoms and phosphate groups are removed from the triose phosphate- which oxidised to two molecules of pyruvate.
during glycolysis there is a net gain of two molecules of apt glucose molecule being used- by substrate level phosphorylation
hydrogens are removed during glycolysis and are transferred to the hydrogen carrier molecule to give reduced NAD.
what happens to pyruvate during aerobic respiration in animals
it’s actively transported into the mitochondria
where does the link reaction take place
in the mitochondrial matrix
outline the link reaction with reference to decarboxylation of pyruvate to acetate and the reduction of NAD
during the link reaction, carbon dioxide is removed from pyruvate (decarboxylation) and the decarboxylase enzyme catalyses it.
the co2 is an excretory product and it diffuses out the mitochondira and out of the cell.
pyruvate is a 3C compound so the removal of co2 leaves a 2C compound.
at the same time as co2 being removed, hydrogen is also removed from pyruvate. the hydrogen is used to reduce NAD
the remainder of the pyruvate (acetate) combines with coenzyme A to produce acetyl CoA.
what does acetate combine with to be carried to the next stage (krebs cycle)
coenzyme A
where does the krebs cycle take place
in the mitochondrial matrix
outline the krebs cycle with reference to the formation citrate from acetate and oxaloacetate and the reconversion of citrate to oxaloacetate
an acetyl group with 2Cs from a CoA is combined with a 4C compound, oxaloacetate to produce a6 carbon compound, citrate. CoA is reformed.
Citrate is converted back to oxaloacetate in a series of small steps involving cebarboxylation and dehydrogenation.
the co2 removed is given off as a waste product
NAD and DAS accept the hydrogens that are removed. 1 FAD and 3 NADs are reduced during each turn of the cycle.
the main role of the krebs cycle is to generate a pool of reduced hydrogen carriers to pass on to the next stage.
the regenerated oxaloacetate can combine with another CoA
one molecule of aTP is made directly by substrate-level phosphorylation for each CoA entering the cycle.
so 2 molecules of ATP are made per glucose molecule entering glycolysis.
what 4 things happens during the krebs cycle
decarboxylation
dehydrogenation
NAD and FAD are reduced
Substrate level phospholytion
outline the process of oxidative phosphorylation, with ref to the roles of electron carriers, oxygen and the mitochondrial cristae
these take place within the inner membrane of the mito- the cristae.
the energy for phosplylating ADP to ATP comes from the activity of the electron transport chain.
hydrogens from reduced FAD and reduced NAD first pass hydrogen carriers in the inner membrane and are then split into hydrogen ions and electrons.
H—> H+ + e-
th electrons pass along a series of electron carriers, each od which is at lower energy than the last.
the hyrdogen ions remain in solution.
the final electron acceptor is oxygen. when oxygen accepts an electron, a hydrogen ion is drawn from the solution to reduce the oxygen to water. hence the ETC and OP need free o2 to occur.
outline the process of chemiosmosis with ref to the ETC, proton gradients and aTP synthase
the transfer of electrons long the series of electron carriers makes energy available for the synthesis of ATP from ADP and Pi, by creating a proton gradient across the inner mitochondrial membrane.
