Respiration Flashcards
Give two examples why plants animals and microorganisms need to respire
Active transport
Metabolic reactions
What is the site of glycolysis?
The cytoplasm
Describe the process of glycolysis
One glucose molecule is phosphorylated requiring 2ATP forming hexose bisphosphate
This then splits into 2 triose phosphate molecules
And is phosphorylated again (substrate level) by inorganic phosphate in cytoplasm to form 2 triose bisphosphate
The triose bisphophates are oxidised forming 2 pyruvates - NAD is reduced as it picks up the H forming NADH for each and 2 ATP molecules are produced from each triosebisphosphate
What is produced in glycolysis?
2 NADH
2 ATP
2 pyruvate
Where does the link reaction occur?
In the mitochondrial matrix- pyruvate enters by active transport by specific carrier proteins
Describe the link reaction
Pyruvate undergoes decarboxylation and dehydrogenation
- removal of co2
- NAD reduced to NADH
Resulting 2carbon Avery group bonds to coenzyme A - acetylCoA
What is produced in link reaction from 1 glucose?
2 co2
2 NADH
2 acetylCoA
AcetylCoA + ____________ = coenzymeA + ________
Oxaloacetate
Citrate
What happens to the citrate molecule in the kerbs cycle to get it to a oxaloacetate?
Decarboxylation and dehydrogenation producing NADH, co2 and 5carbon compound
Further decarboxylation and dehydrogenation forming NADH, co2 and 4 carbon compound
Further decarboxylation and dehydrogenation forming co2, 2x NADH, FADH2, ATP and oxaloacetate
Why isn’t respiration 100% Yeild of atp?
Some ATP used to transport pyruvate into mitochondrion
Some ATP used to actively transport H+ from NADH formed in glycolysis into mitochondrion
Some energy released in ETC as heat
Not all H+ movement back across membrane used to generate ATP/ goes through ATP synthase
Not all NADH used to feed into ETC
What is oxidative phosphorylation?
Process where energy carried by electrons form reduced coenzymes (NADH and FADH2) is used to make ATP
Describe the electron transport chain
Hydrogen atoms released as NADH/Fdh2 is oxidised dissociate into H+ and e-
Electrons move along electron transport chain (made of electron carriers) losing energy at each carrier
Energy is used by electron carriers to pump protons from mitochondrial matrix into intermembrane space
Electrochemical gradient forms
Protons move down electrochemical gradient into mitochondrial matrix via ATP synthase driving ATP from ADP and inorganic phosphate- chemiosmosis
In the mitochondrial matrix the protons, electrons and o2 combine to form water- o2 being the final electron acceptor
why does aerobic respiration not always produce the expected yeild of ATP?
some ATP is used to transport pyruvate in the mitochondrion by active transport
some ATP used to actively transport hydrogen ions from reduced NAD into mitochondria from glycolysis
some energy in electron transport chain not used to transport hydrogen ions and lost as heat
not all hydrogen ion movement is used to generate ATP/ is through ATP synthase
not all reduced NAD is used in ETC
what is the process of anaerobic respiration in mammals?
lactate fermentation
pyruvate molecule is reduced to lactate which oxidises reduced NAD so produces NAD which can be used in glycolysis
what is the process of anaerobic respiration in yeast?
alcoholic fermentation
pyruvate molecules is decarboxylated producing ethanal and carbon dioxide and then reduced to ethanol, oxidising reduced NAD to NAD which can be used in glycolysis
why is alcoholic fermentation irreversible?
the process removes carbon dioxide from the pyruvate molecule and decarboxylase enzyme cannot reverse the reaction
what is the order of relative energy values of lipids, proteins, and carbohydrates from lowest to highest energy
carbohydrates
proteins
lipids
what is the RQ of protein?
0.9
what is the RQ of carbohydrate?
1
what is the RQ of lipids?
0.7
why have lipids got a high energy content?
fatty acids have more hydrogen atms
so can be oxidised many times by the krebs cycle
so many reduced NAD produced in krebs cycle
so more reduced NAD available for oxidative phosphorylation so more ATP produced
what are two qualitative changes that take place in the intermembrane space of the mitochondria as a result of oxidative phosphorylation?
pH decreases
becomes more positivelt charged
explain how having a larger number of proton pores in the inner mitochondrial membrane would result in a person less likely to gain weight
• larger number of protons pores results in protons leaking back into matrix • reduces yield of ATP from chemiosmotic gradients • less ATP is made from oxidative phosphorylation • more energy wasted as heat • energy from chemiosmosis decoupled from ATP synthesis • energy yield from aerobic respiration reduced per molecule of glucose • food not converted to ATP as efficiently • less excess energy intake in diet • less deposition of fat • fat stores may be respired for energy
why cant you measure the RQ of maggots or yeast when theyre under anaerobic conditions?
maggots will not produce CO2 in lactate fermentation
yeast will not produce CO2 in alcoholic fermentation
measuring RQ requires CO2 production so RQ will be lower than normal
