Respiration Flashcards
Aerobic respiration
6O2 + C6H12O6 -> 6H2O + 6CO2 + ATP
36-38 ATP
20 chemical reactions, 4 phases
Red blood cells
No organelles
Can’t respire aerobically
Anaerobic respiration advantages
No need for mitochondria or oxygen
Facultative/ obligate anaerobes
Prokaryotic
Rely on anaerobic resp.
Why is there a rise in temp.?
Energy generated lost as heat
Anaerobic respiration in animals
Glucose -> lactic acid
C6H12O6 -> 2C3H6O3
Anaerobic respiration in fungi
Glucose -> ethanol + CO2
C6H12O6 -> C2H5OH + CO2
Anaerobic respiration aka
Fermentation
ATP
V soluble but doesn’t diffuse
NAD
A coenzyme
A hydrogen carrier
Glycolysis intro
Splitting glucose (occurs in cytoplasm)
Necessary because mitochondria have channel proteins for pyruvate and not glucose
Has to make glucose reactive, to overcome Ea
Glycolysis details
- phosphorylation -> glucose-6-phosphate (traps inside cell)
- isomérisation (isomerise) -> fructose-6-phosphate
- phosphorylation (phosphofructokinase) -> fructose-1,6-diphosphate
- splits into 2x triose phosphate
- TP oxidised -> à series of intermediates -> pyruvate
- provides energy for substrate-level phosphorylation
Phosphorylation
Uses ATP
Glycolysis net products
2 pyruvate, 2ATP, 2NADH2
Link reaction
- pyruvate diffuses/actively transported into the mitochondrial fluid matrix - needs a carrier (ATP)
- 2x pyruvate decarboxylated -> 2x acetyl
- acetyl associates with coenzyme A
- pyruvate is oxidised, NAD is reduced
Mitochondrial fluid matrix
Gel- where all the enzymes are
Coenzyme À
Acceptor molecules
Only take 2 molecules of pyruvate
Recycled
Decarboxylation
Hence the CO2 product
Krebs Cycle function
To regenerate acceptor molecule, extracting hydrogen for oxidative phosphorylation
Krebs cycle details
- acetyl coA -> via a series of intermediates -> citrate
- citrate decarboxylated -> glutartic acid, NAD reduced
- glutartic acid decarboxylated -> ocyloacetate, FAD reduced
- substrate-level phosphorylation produces 2x ATP
Products: 4x CO2
Oxidative phosphorylation details
1) NADH2 and FADH2 release hydrogen into inner mitochondrial membrane; oxidised
2) hydrogen splits into protons and electrons
3) electrons flow down electron carriers of decreasing energy levels; the electron transport chain - leaves energy
4) electron leaves proton electrically imbalanced; protons join from matrix to balance
5) electron moves, leaving chemical imbalance
6) energy used to pump protons across membrane after accumulation (electrochemical gradient; proton motive force)
7) protons flow through ATP synthase
8) energy translated into ADP substrate-level phosphorylation
Where does oxidative phosphorylation occur?
At the cristae Many High SA Greater rate of flow More ATP production
OXIDATIVE phosphorylation
- oxygen is the final electron acceptor in the matrix
- protons join to form water
1/2O2 + 2H+ + 2e- -> H2O
Catalyses by cytochrome oxidase
Why is the yield not reached?
- transporting NADH2 into mito
- active transport of pyruvate
- leaky protons
- NADH2 used elsewhere
Chemiosmosis
- proton motive force
* high -> low across a membrane
Investigating respiration rate
Using yeast mitochondria to observe mitochondria at the cellular level
Indicator: CO2
Acclimation/équilibration
Yay
Respirometers all contain:
- organism (+ control)
- manometer tube (contains coloured liquid and scale)
- soda lime/ KOH (absorbs CO2; allows tracking of oxygen usage)
- cotton wool (allows O2 but not […]
- screws (airtight; open during équilibration)
- syringe (push air back into system to push fluid back into measurable scale)
- Barrier (separate organism from soda lime)
- water-bath (constant temp.)
Respiratory quotient definition
Measure of the ratio of CO2 given out compared to the O2 consumed by an organism over a given period
Respiratory quotient examples
Glucose: 1.0
Lipids: 0.7
Protein: 0.9
Organisms rarely respire just one substrate; produces intermediate values
Most organisms resting RQ: 0.8-0.9
How does stage 2 (pyruvate -> ethanol and CO2) of anaerobic respiration allow stage 1 (glucose -> pyruvate) to continue
Regeneration of NAD allows continuation of glycolysis
Acetyl CoA formation
Pyruvate is oxidised in a decarboxylation reaction; coenzyme A is added
Why might glucose not be used in an investigation?
It is broken down during glycolysis in the cytoplasm - cannot cross the mitochondrial membrane
Ice cold
Isotonic
Reduce enzyme activity
Prevents osmosis - no shrivel