M5 C18: respiration Flashcards
why do we need respiration?
need energy for metabolic reactions such as protein synthesis, maintaining temperature
what is the respiration equation?
C6H1206 + 6 O2 → 6 CO2 + 6 H20 + 2870kJ
what is the function of mitochondrion?
synthesize ATP
how many membranes do mitochondria have?
2
what is the outer membrane of the mitochondria?
Smooth
Permeable to several small molecules
what is the inner membrane of the mitochondria?
Folded (cristae)
Less permeable
The site of the electron transport chain (used in oxidative phosphorylation)
Location of ATP synthase enzymes (used in oxidative phosphorylation)
what are some key features about the intermembrane space?
Has a low pH due to the high concentration of protons
The concentration gradient across the inner membrane is formed during oxidative phosphorylation and is essential for ATP synthesis
what are some features of the matrix?
Is an aqueous solution within the inner membranes of the mitochondrion
Contains ribosomes, enzymes and circular mitochondrial DNA necessary for mitochondria to function
what are the 4 stages of aerobic respiration?
glycolysis
link reaction
Krebs cycle
Oxidative phosphorylation
what is the result of glycolysis?
2 Pyruvate (3C) molecules
Net gain 2 ATP
2 reduced NAD
what happens in phosphorylation in glycolysis?
glucose (6C) is phosphorylated by 2 ATP to form hexose bisphosphate (6C) this then splits into 2 triose phosphate molecules (3C)
what happens in oxidation in glycolysis?
hydrogen is removed from each molecule of triose phosphate and transferred to coenzyme NAD to form 2 reduced NAD
4H + 2NAD → 2NADH + 2H+
what happens in dephosphorylation in glycolysis?
phosphates from triose bisphosphate and from cell cytoplasm are transferred from the intermediate substrate molecules to form 4 ATP through substrate-linked phosphorylation
4Pi + 4ADP → 4ATP
what happens after pyruvate is produced?
When oxygen is available pyruvate will enter the mitochondrial matrix and aerobic respiration will continue
what happens after dephosphorylation in glycolysis?
pyruvate is produced (3C) which is used in the next stage of respiration
how does the pyruvate move across the membrane?
active transport
what happens in the link reaction?
-pyruvate moves into matrix
-Pyruvate is oxidised by enzymes to produce acetate, CH3CO(O)- and carbon dioxide, requiring the reduction of NAD to NADH
- Combination with coenzyme A to form acetyl coenzyme A (acetyl CoA)
what are the products of link reaction?
acetyl CoA + carbon dioxide + reduced NAD
where does the krebs cycle take place?
in the matrix
what happens to acetyl CoA at the start of the krebs cycle?
-carbon (4C) oxaloacetate accepts the 2C acetyl fragment from acetyl CoA to form the 6 carbon (6C) citrate
Coenzyme A is released in this reaction
what happens after citrate is made in the krebs cycle?
Decarboxylation of citrate
Releasing CO2 as waste gas making it now a 5C compound
Oxidation (dehydrogenation) of citrate
Releasing H atoms that reduce NAD
what happens to the 5C compound in the krebs cycle?
it is decarboxylised meaning it is now a 4C compound
dehydrogenated- reduicng NAD to NADH
adp then becomes atp due to the addition of a phopshate
FAD and NAD are then reduced and the compound is now oxaloactate (4C)
what happens to FAD and NAD in oxidative phosphorylation?
reduced NAD and FAD deliver their hydrogen atoms to the electron transport chain causing them to be reoxidised
what happens after NAD and FAD are deoxidised?
the hydrogen atoms split to become protons and electrons.
h+ ions go into the matrix through proteins
e- are accepted by the first electron carrier protein in the chain
how do the proteins in the membrane accept the electron?
iron at centre of carrier becomes reduced, the elcetron is then donated to the next protein in the chain and so on
what does the energy released from the electrons going down the electron transport chain do?
used to pump the h+ ions from the matrix to the intermembrane space
what happens after the h+ ions are in the intermembrane space?
proton gradient forms across the membrane
what happens due to the proton gradient?
H+ ions diffuse through the channels and form a comformational change in the atp synthase enzyme. this catalyses ADP to ATP.
what happens to the electrons in the electron transport chain?
oxygen combines with the electrons that have come off the last protein and also combine with the protons forming water
why is oxygen needed for respiration?
electron cant be received by final electron receptor so NAD wont be oxidized to be recycled
what are the 2 pathways of anaerobic respiration?
lactate pathway
ethanol fermentation pathway
what happens in the lactate pathway?
the pyruvate accepts hydrogen atom from the reduced NAD becoming lactate. this then can become oxidized and recycled in glycolysis.
what enzyme catalyses the pyruvate molecules accepting the h+ atoms from NAD?
lactate dehydrogenase
what happens in the ethanol fermentation pathway?
the pyruvate loses a carbon to release CO2 and become ethanal. this then gains hydrogen atoms from reduced NAD, which is then reoxidsed to be used again
how do you calculate respiratory quotient?
volume of CO2 out divided by volume of O2 in
what is the respiratory quotient of glucose in anerobic respiration?
1 or over
what is the respiratory quotient of carbohydrates in aerobic respiration?
1
what is the respiratory quotient of proteins and lipids in aerobic respiration?
proteins- 0.9
lipids - 0.7
how does a respirometer work?
used to measure the rate of oxygen consumption during aerobic respiration consists of a chamber containing the organism or tissue, a manometer to measure pressure changes, and an absorber of carbon dioxide1.
measuring changes in gas volumes allows us work out rate of respiration
what is different between a simple and complex respirometer?
complex has 2 tubes 1 being a control
