Respiration chp 18 Flashcards
what is the first stage of respiration
- Glycolysis
at what stage does aerobic and anaerboic respiration split off in the stages of respiration
- glycolysis
what is the name of all the stages (in order) of aerobic respiration
- glycolysis
- link reaction
- krebs cycle
- oxadative phosphorylation
what is the name of all stages (in order) of anaerobic respiration
- glycosis
- fermentation
where does glycolysis occur within the cell
- occurs in the cytoplasm
is glycolysis an aerobic or anaerobic process, why is this
- anerobic process as does not require oxygen
what is the products of glycolysis
- 2 pyruvate molecules (3 carbon molecules)
- 2 ATP
- 2NADH
what are the main steps of glycolysis
- phosphorylation forms hexosebisphosphate
- lysis forms triosephosphate
- phosphorylation to form triosebisphosphate
- dehydrogenation and formation of ATP to produce pyruvate
what occurs in the phosphorylation (1st) stage of glycolysis
- requires 2 molecules of ATP
- 2 phosphates released from ATP molecules are attached to glucose molecule
- ^forms hexose bisphosphate
what occurs in the lysis (2nd) stage of glycolysis
destabilises the molecule of hexose bisphosphate, causing it to split into 2, triose phosphate molecules
what occurs in the 2nd phosphorylation (3rd) stage of glycolysis
- phosphate group added to each triose phosphate,
- ^forms 2 triose bisphosphate molecules
- inorganic phosphate groups come from cytoplasm (free floating)
what occurs in the dehydrogenation and ATP formation (final) stage of glycolysis
- 2 triose bisphosphate molecules oxidised (via removal of hydrogen) forming 2 pyruvate molecules
- NAD coenzymes accept removed hydrogens (they are reduced to form 2 NADH molecules)
- 4 ATP molecules produced using phosphates from 2 triose bisphosphate
^ however net gain of 2 ATP
what is meant by substrate level phosphorylation
- formation of ATP without use of electron transport chain
where does substrate level phosphorylation occur in glycolysis
- the final stage
- ^dehydrogenation and ATP formation
what is the overall net ATP yield from glycolysis
- 2 molecules used at start, 4 molecules produced
- net yield = 2 ATP molecules
where does aerobic respiration take place within the cell (apart fromn glycolysis)
- inside the mitochondria
what is the function of the inner mitochondrial membrane
- contains electron transport chains and ATP synthase
refers to cristae
what is the function of the outer mitochondrial membrane
- compartmentalisation to maintain ideal conditions
what is the function of the cristae in the mitochondria
- projections of inner membrane
- increase surface area available for oxidative phosphorylation
what is the function of the matrix in the mitochondria
- contains enzymes for the Krebs cycle and link reaction
- contains mitochondrial DNA
what is the function of the intermembrane space found within mitochondria
- protons pumped into this by electron transport chain
- space small so concentration builds up (conc gradient)
what is the more descriptive name for the link reaction
- oxidative decarboxylation
how does pyruvate enter the mitochondrial matrix
- active transport via carrier proteins
what is meant by oxidative decarboxylation
removal of carbon and hydrogen
what happens to the the hydrogen atoms that are removed from pyruvate in the link reaction
- accepted by NAD to form NADH (reduced NAD)
what is the product of the link reaction
- acetyl groups (2 carbons)
- ^bind to coenzyme A forming acetylcoenzyme A
where does the krebs cycle occur within the cell
- takes place in mitochondrial matrix
where does link reaction take place within cell
- mitochondrial matrix
Draw the krebs cycle
what main processes occur in the krebs cycle
- acetyl CoA delivers acetyl to Krebs cycle (Co A recycled in links)
- acetyl groups (2 C) combine with oxaloacetate (4 C) to form citrate (6 C)
- citrate undergoes decarboxylation and dehydrogenation
^5 carbon compound formed - 5C compound undergoes decarboxylation and dehydrogenation
- ^oxaloacetate regenerated
whats the products of the Krebs cycle
- 3 reduced NAD (NADH)
- ATP
- FADH2
- 2 CO2 molecules
what are NAD and FAD examples of
- coenzymes that accept electrons and protons
what are the differences between NAD and FAD
- NAD is found in all stages of cellular respiration, FAD only found in Krebs cycle
- NAD accepts 1 hydrogen, FAD accepts 2
how are Red. NAD and FAD used in oxidative phosphorylation
- deliver protons/H+ and electrons to the Cristae of the mitochondria
how are electrons utilised in oxidative phosphorylation
- used to generate energy via travelling along an electron transport chain for active transport of hydrogen ions across cristae
- combine with hydrogen ions and oxygen to form water
Why are hydrogen ions actively pumped across the mitochondiral cristae into the intermembrane space
- to generate a high concentration gradient across the crista so that hydrogen ions move through ATP synthase to produce ATP
How is oxygen used in the oxadative phosphorylation
- oxygen accepts hydrogens and electrons to form water molecules
- ^this maintains the concentration gradient of hydrogen so that diffusion keeps occuring through ATP synthase
- ^also acts to reduce acidity that can come about due to high levels of H+ ions (high acidity can denature enzymes involved in electron transport chain and ATP synthase)
Draw oxadative phosphorylation
draw glycolysis, links reaction and krebs cycke from aerobic respiration
what is the net gain of ATP in aerobic respiration
net gain in each stage
- glycolysis: 2 ATP in, 4 ATP out = net gain 2
- link reaction: 0 in, 0 made = 0 net
- Krebs cycle: 0 in, 2 made = net gain 2
- oxadative phosphorylation: 0 in, 34 made = 34 net gain
40-2=38
what are obligate anaerobes
- cannot survive in presence of oxygen
what are facultative anaerobes
- synthesise ATP by aerobic respiration if oxygen is present, but can switch to anaerobic respiration in absence of oxygen
what are obligate aerobes
- can only synthesise ATP in presence of oxygen (mammals)
what is fermentation
- form of anaerobic respiration
- process by which complex organic compounds are broken down without use of oxygen or involvement of electron transport chains
what can do alcoholic fermentation
- yeast and some plant root cells
what are the end products of alcoholic fermentation
- ethanol (alcohol) and carbon dioxide
what are the products of the lactate fermentation
- lactate
- carried out In animal cells
why does aerobic respiration stop when there is the absence of oxygen
- no oxygen to act as the final electron acceptor at the end of the electron transport chain, the flow of electron stops
- synthesis of ATP by chemiosmosis stops
- as flow of electrons has stopped, red. NAD & red. FAD are no longer oxidised as no where for electrons to go
- FAD and NAD not regenerated so decarboxylation and oxidation cannot occur in links and Krebs, this means they stop as no coenzymes available
- glycolysis would stop if not for fermentation
draw lactate fermentation in mammals
what enzyme catalyses lactate fermentation
lactate dehydrogenase
why cannot lactate fermentation occur indefinitely
- amount of ATP made would not sustain vital processes in the long run
- accumulation of lactic acid causes fall in pH leading to proteins denaturing.
^respiratory enzymes and muscle filament will cease to function at low pH
draw alcoholic fermentation
which type of fermentation is reversible and which one is not
- alcoholic fermentation is not reversible
- lactate fermentation is reversible
what enzyme catalyses alcoholic fermentation
pyruvate converted to ethanal first catalysed by pyruvate decarboxylase
where does lactic acid go to be dealt with in the body
removed from muscles and taken to liver in bloodstream and converted into glucose but oxygen is needed to do so
explain the steps of alcoholic fermentation
- pyruvate is first converted to ethanal, catalysed by pyruvate decarboxylase
- ethanal then accept hydrogen from red. NAD, becoming ethanol
- NAD regenerated so glycolysis can continue
explain the steps of lactate fermentation
- pyruvate acts as hydrogen acceptor taking hydrogen from red. NAD, catalysed by enzyme lactate dehydrogenase
- pyruvate converted into lactate (lactic acid) which can produce glucose and NAD is regenerated
^can be used to maintain glycolysis
which type of fermentation can occur indefinitely
- alcoholic fermentation can occur indefinitely in the absence of oxygen
what are some ways that some animals have evolved to low oxygen environments
- higher concentrations of haemoglobin and myoglobin, particularly in muscles
^maximises oxygen stores, delays onset of anaerobic respiration - higher tolerance to lactic acid
- greater tolerance of high CO2 levels
- ^very effective buffering systems to stop pH fall
- bradycardia
what are respiratory substrates
organic molecules that are broken down to release energy for the synthesis of ATP
what are some examples of respiratory substrates apart from glucose
- triglycerides
- glycerol
- lipids
- proteins
how can triglycerides act as respiratory substrates
- hydrolyses to fatty acids, which enter Krebs cycle via acetyl CoA and glycerol
- can produce up to 50 acetyl CoA molecules, can result in up to 500 ATP molecules
How can glycerol act as respiratory substrates
- first converted to pyruvate before oxidative decarboxylation producing acetyl group, then forms acetyl CoA
how can proteins act as respiratory substrates
- first have to be hydrolysed to amino acids, then deaminated to pyruvate which enters links
what is the equation to find the respiratory quotient
what equipment can be used to measure respiratory quotient
respirometer
what are the respiratory quotient values of carbohydrates, proteins and lipids
- carbohydrates = 1.0
- protein = 0.9
- lipids = 0.7
at what point of respiratory quotient value does anaerobic respiration start
- if the RQ value increases above 1.0 anaerobic respiration begins
what are some issues with low carb diets
- can lead to breakdown of lean muscle
- liver and kidneys have to remove nitrogenous waste
- if body produces lots of ketones, can lead to ketosis, which can lead to ketoacidosis, pH level in body drops to dangerous levels
