Respiration Flashcards
catabolic reaction
breaking down of complex molecules in to smaller molecules
anabolic reaction
builds molecules the body needs
stages of respiration and where they take place
glycolysis-cytoplasm of cell
link reaction-matrix of mitochondria
krebs cycle- matrix
electron transport chain- utilises proteins found in membrane of the cristae
glycolysis
-first stage of anaerobic and aerobic respiration
-carbohydrate splitting
-occurs in cytoplasm, anaerobic process
2 stages: phosphorylation, oxidation
stages of glycolysis
-glucose is phosphorylated into glucose phosphate (6C) by 2xATP
-glucose phosphate splits into 2x3C molecules of triose phosphate (TP)
-TP is oxidised to form 2xpyruvate
-NAD collects H+ ions forming 2 reduced NAD
-net gain of 2x ATP
why is there a net gain of ATP
4 ATP are produced, but 2 were used at the start, so net gain of 2 ATP
products of glycolysis and where they go
-2 reduced NAD- goes to the ETC
-2 pyruvate- actively transported into mitochondria for link reaction
-2 ATP- used for energy
link reaction
-oxidative carboxylation- removal of CO2 and H+ from pyruvate producing acetate.
-H+ ions is accepted by NAD forming reduced NAD
-acetate combines with coenzyme A (CoA) to form acetylcoenzyme A- enters Krebs cycle
summary equation for link reaction
pyruvate+ CoA+ NAD-> acetyl CoA+ reduced NAD+ CO2
krebs cycle
a series of redox reactions produces:
-ATP by substrate level phosphorylation
-reduced coenzymes
-CO2 from decarboxylation
stages of krebs cycle
-acetate is removed from CoA and combines with a 4C molecule of oxoloactic acid to form 6C sugar-citrate
CoA goes back to link reaction
-citrate is decarboxylated and dehydrated - 2H+ions are used to reduce NAD.
-5C molecule now, a phosphate removed to generate ATP=substrate level phosphorylation
-it is decarboxylated + dehydrated again to produce a 4C molecule, another CO2 and NADH.
-the 4C compound is dehydrogenated again and 2H+ ions reduce FAD.
what happens in ETC
-electrons released from reduced NAD and FAD undergo successive redox reactions.
-the energy released s coupled to maintaining proton gradient or released as heat.
-oxygen acts as final electron acceptor
coenzymes
molecules that some enzymes require in order to function e.g. NAD, FAD, NADP
significance of krebs cycle
-breaks down macromolecules into smaller molecules: pyruvate->CO2
-produces H atoms that are carried by NAD to ETC for oxidative phosphorylation, leading to production ATP
–source of immediate compounds used by cells to manufacture other compounds e.g. fatty acids, amino acids
oxidative phosphorylation
-reduced NAD and FAD donate the electrons of H atoms they are carrying to first molecule of ETC.
-electrons pass along a chain of electron transfer carrier molecules in a series of redox reactions.
-energy released from redox reactions in ETC causes the active transport of protons (H+ ions) from the mitochondrial matrix into the intermembrane space
-H+ ions move down their concentration gradient from intermembrane into mitochondrial matrix via channel protein ATP synthase.
ATP synthases catalyses ADP+Pi-> ATP
benefit of an ETC rather than a single reaction
energy is released gradually
less energy is released as heat
2 molecules that can be used as alternative substrates
-amino acids from proteins
-glycerol and fatty acids from lipids
how can lipids act as alternative respiratory substrates
-lipids first hydrolysed to glycerol and fatty acids
-glycerol is phosphorylated and converted into TP-used for glycolysis and subsequently krebs cycle
-fatty acid is broken into acetate
-acetate enters the link reaction
-H atoms produced for oxidative phosphorylation
how can amino acids act as alternative respiratory substrates
-hydrolysed into amino acids
-deamination-amine group removed & enters respiratory pathway at different points depending on number of C atoms they contain.
-3C compounds->pyruvate for link reaction
-4C/5C compounds->intermediates in Kreb’s cycle
anaerobic respiration in animals
only glycolysis continues
reduced NAD+ pyruvate-> oxidised NAD (for further glycolysis) + lactate
what happens to lactate produced in anaerobic respiration
transported to liver via the bloodstream, where it is oxidised to pyruvate.
can enter link reaction in liver cells or be converted to glycogen.
anaerobic respiration in yeast+ plant cells
only glycolysis continues
pyruvate is decarboxylated to form ethanal
ethanal is reduced to ethanol using reduced NAD to produce oxidised NAD for further glycolysis.
advantage of producing ethanol/lactate during anaerobic respiration
converts reduced NAD back into NAD so glycolysis can continue
disadvantage of producing ethanol during anaerobic respiration
-cells die when ethanol concentration is above 12%
-ethanol dissolves cell membranes
disadvantage of producing lactate in anaerobic respiration
acidic, so decreases pH
results in muscle fatigue
respiratory quotient
RQ= CO2 produced/ O2 consumed
if RQ>1, anaerobic respiration is occurring
compensation point
the light intensity at which the rate of photosynthesis will match rate of respiration
advantage of muscle cells having more mitochondria (2)
mitochondria produces ATP from aerobic respiration, more ATP produced so more energy can be released.
use of hydrolysis of ATP in cells (2/3)
-provides energy for active transport
-synthesis of molecules e.g protein
-add phosphate to other substances, makes them change
in a sprint, why is more energy provided by anaerobic respiration than aerobic (2)
-energy demand is really high, not enough time for oxygen to reach muscles
why is less energy released by anaerobic (1)
glucose is only partly broken down as only glycolysis takes place
describe how ATP is made in mitochondria (6)
-ATP is produced in kreb’s cycle by substrate level phosphorylation: phosphate group is removed from 5C molecule to produce ATP
-kreb’s cycle + link reaction produce reduced NAD
-electrons released from reduced NAD and FAD enter electron transport chain
-energy is released by -redox reactions of electrons
-energy used for active transprot of H+, H+ move down concentration gradient trough ATP synthase channel
-ATP synthase catalyses the reaction to produce ADP + Pi-> ATP
why is it important plants produce ATP in photosynthesis and respiration (5)
-when it is dark, ATP not produced by photosynthesis
-ATP is need to provide energy for active transport of ions
-some tissues e.g. unable to photosynthesise
-ATP cannot be moved from cell to cell
-plants use more ATP than produced in photosynthesis
