5.2.2 - respiration Flashcards
aerobic respiration, anaerobic respiration, respiratory substrates and RQs
first stage of respiration
glycolysis
is glycolysis aerobic or anaerobic?
anaerobic - does not require oxygen
first step of glycolysis
phosphorylation - uses 2 molecules of ATP and forms hexose bisphosphate
what happens to hexose bisphosphate in glycolysis
splits into two TP molecules
products of glycolysis
2 pyruvate molecules
2 NAD molecules
4 ATP (only a net gain of 2, as 2 are used in phosphorylation)
substrate level phosphorylation
formation of ATP without the involvement of an electron transport chain.
why is the link reaction called the link reaction?
it is the step that links anaerobic glycolysis in the cytoplasm to the aerobic steps of respiration
how does pyruvate enter the mitochondrial matrix
active transport via specific carrier proteins
decarboxylation
carbon dioxide being removed
products of the link reaction
acetyl coA
reduced NAD
Co2
what is the waste product of the link reaction
co2
role of acetyl coA
delivers the acetyl group to the next stage of aerobic respiration (Krebs)
where does the krebs cycle take place?
matrix
products of the krebs cycle
FAD, NAD, small amounts of ATP, Co2
first step of the krebs cycle
acetyl coA delivers an acetyl group to the Krebs cycle - combines with 4C oxaloacetate to form 6C citrate
role of coenzymes
required to transfer protons, electrons and functional groups
differences between NAD and FAD
- NAD takes part in all stages of cellular respiration, FAD only in krebs
- NAD accepts 1 hydrogen and FAD accepts 2
- NADH is oxidised at the start of the ETC, FAD is oxidised further along
- reduced NAD results in the synthesis of 3 ATP molecules, whilst FAD results in 2.
what are coenzymes usually derived from?
vitamins
where does oxidative phosphorylation take place?
cristae
what are the products of the last stage of respiration
lots of ATP
h2o
what is the role of oxygen in OP?
final electron aceptor
what is the phosphorylation of ADP dependent on?
electrons moving along the electron transport chain
how is water formed in OP?
hydrogens released from NAD and FAD combine directly with oxygen
anaerobic respiration
resulting in the synthesis of smaller quantities of ATP, occurs in the absence of oxygen
obligate anaerobes
cannot survive in the presence of oxygen - mainly prokaryotes
facultative anaerobes
synthesise ATP by aerobic respiration if oxygen is present, but can switch to anaerobic - e.g yeast
obligate aerobes
can only synthesise ATP in the presence of oxygen - e.g mammals (individual cels maybe not, but overall obligate aerobes)
fermentation
process by which complec organic compounds are broken down into simpler inorganic compounds withouy the use of oxygen or involvement of an ETC.
alcoholic fermentation - where?
occurs in yeast and some plant cells
products of alcohol fermentation
ethanol and carbon dioxide
why does the flow of electrons stop with no oxygen?
as it is the final electron acceptor
what happens to the coenzymes when there is no oxygen
no flow of electrons so reduced NAD and FAD can not be oxidised as there is no where for the electrons to go
what happens to the krebs and link reaction when no oxygen
comes to a stop as coenzymes cannot be regenerated
lactate fermentation - where?
mammals
lactate fermentation - what is the hydrogen acceptor?
what enzyme catalyses this?
- pryruvate
- lactate dehygrogenase
what is pyruvate converted to in lactate fermentation ?
lactic acid
what happens to lactcic acid ?
converted back to glucose in the liver in liver (but oxygen is needed)
why is lactate fermentation not sustainable?
- reduced quantity of ATP produced would not be enough tio maintain vital processes
- accumulation of lactic acid causes a fall in pH causing enzymes to be denatured
differences between alcohol and lactate fermentation
- alochol fermentation is not a reversible process
- ethanol produced instead of lactic acid
- not a short term process
respiratory substrates
organic molecule that is broken down to release energy for the synthesis of of ATP
lipids and release of energy
release about twice as much energy as carbohydrates due to carbon hydrogen bonds
lipids and co2 release
relatively less produced, as more o2 is needed
respiratory quotient
RQ = co2 produced / o2 consumed
RQ for carbs, protein and lipids
- carbohydrates = 1.0
- proteins = 0.9
- lipids = 0.7
