Respiration

1. Phosphorylation

• 1 ATP hydrolysed, phosphate goes to C6 = gluc-6-P converted fruc-6-P
• Other ATP hydrolysed, phosphate C1 = fruc 1,6-bisphos & energy activates = hex 1,6-bis

2. Splitting of hexose 1,6-bisphosphate

• Each molecule split into 2 triose phosphate

3. Oxidation of triose phosphate

• 2 H atoms removed w/ use dehydrogenase & aided by NAD = NADH
• 2 molecules NADH made & 2 molecules ATP formed (substrate-level-phosphorylation)

4. Conversion of triose phosphate to pyruvate

• 4 enzyme-controlled reaction convert each TP to pyruvate
• Another 2 molecules ADP phosphorylated ATP

each molecule glucose 4 ATP made, 2 used so net gain = 2 & 2 NADH + pyruvate made

Metbolic reactions need energy:

• active transport; move ions/molecules across membrane against conc grad
• secretion; large molecules made to be exported by exocytosis
• endocytosis; bulk movement large molecules into cell
• synthesis of large molecules from smaller; ie proteins from amino acids
• replication of DNA & synthesis of organelles before cell divides
• movement; ie bacterial flagella
• activation of chemicals; ie glucose phosphorylated @ beginning so more unstable + broken
  

Some energy from catabolic reactions = heat useful as reactions controlled by enzymes

Energy from photoautotrophs- use sunlight = large, organic molecules consumer & decomposers use (ie. plants, some protoctsists + bacteria)

Respiration releases energy used to phosphorylate ADP to ATP

- release of energy from substrates in absence of oxygen

• oxygen = final e acceptor in OP but if absent ETC can't function so Krebs/link stops
  
  
• only glycolysis occurs + only source ATP
  
  
• NADH generated during oxidation has to be reoxidised so glycosis keeps operating increasing chance organism surviving under temp adverse conditions

EUK 2 pathways reoxidise NAD

• fungi, like yeast, use ethanol fermentation
• animals use lactate fermentation

neither produce any ATP but 2 mole of ATP per molecule glucose made by substrate-level phospo (glyco = 2 ATP, NADH, pyruvate per molecule glucose)

pyruvate to lactate w/ help lactate dehydrogenase + donation H from NADH = NAD

occurs mammalian muscle tissue during vigorous activity when demand ATP high & is an oxygen deficit

• NADH reoxidised to NAD+
• pyruvate = H acceptor (accepts H atoms from NADH)
• NAD = reoxidised & available accept more H atoms from glucose
• glycosis can continue, generating enough ATP sustain muscle contraction
• enzyme lactate dehydrogenase catalyses oxidation of NADH together w/ reduction of pyruvate to lactate

lactate carried in blood away from muscles to liver

when more O available lactate converted back to pyruvate- enter Krebs via link or directly

muscle fatigue caused by reduction in pH reduces enzyme activity in muscle not build up lactate

lipids; triglycerides hyudrolysed by lipase to f. acids + glycerol (converted glucose)

• long chain HC so many H-C bonds
  
• source of many protons for oxidative phospho = lots ATP made
  
  
• each f. a combined w/ CoA needs energy from hydrolysis molecule ATP to AMP + 2Pi
• f. a - CoA complex transported to matrix broken into 2 acetyl groups attached to CoA
• during this NADH + FADH formed
  
  
• acetyl groups released from CoA & enter Krebs where 3 NADH,, 1 NADH, 1 ATP made
• lots NADH reoxidised @ ETC during ox phospho = lots ATP by chemiosmosis

on ave.

carbs = 15.8 kJ/g |  lipids = 39.4 kJ/g |  protein = 17.0 kJ/g

before OP 4 molecules ATP gained/made substrate level phosphorylation

more ATP made during OP as NADH + FADH reoxidised - 10 NADH, 2 FADH altogether

• both provide e to ETC used OP
  
• NADH also H ions contribute build up gradient for chemiosmosis but FADH H ions stay matrix but can combine w/ O2 make water
  
  
• 10 molecules NADH theoret = 26 mole ATP during OP so each molecule NADH up to 2.6 mole ATP should be made
• together w/ ATP total yield ATP molecules should be 30

rarely achieved bc;

• some protons leak across membrane reducing numb protons generate proton motive force
• some produced is used a. transport pyruvate into mitochondria
• some used for shuttle to bring H from NADH made during glycosis into the mitochondria

an organic substance that can be used for respiration

• maj ATP produced during oxidative phospho protons flow through channels associated ATP synthase & H ions + e = H2O so more protons = more ATP
  
• more H atoms in respiratory subst = more ATP when respired = more O2 needed respire

carbs; monosaccharides converted to glucose for respiration

• theoretical yield 2870 kJ/mol & takes 30.6 kJ for 1 mol ATP
• theoretically 1 mol glucose = nearly 94 mol ATP but actually around 30 w/ efficiency 32%
• remaining energy released as heat maintains body temp = ECR proceeds

protein; excess a.a deaminated and rest changed glycogen/fat to store + later release energy

• fast/starve/prolonged exercise protein from muscle hydrolyses to a.a respired
• some convert to pyruvate, or acetate, carried to Krebs or enter directly
• num H atoms per mole accepted by NAD + then used OP slightly more than num H atoms per mole of glucose

pyruvate to ethanal (w/ help pyruvate decarboxylase so release CO2) to ethanol (ethanol dehydrogenase where NADH becomes reoxidised)

• each pyruvate loses CO2 molecule, decarboxylated, to become ethanal which is catalysed by pyruvate decarboxylase that has coenzyme bound to it
  
  
• ethanal accepts H atoms from NADH, becomes reoxidised as ethanal is reduced to ethanol (ethanol dehydrogenase)
  
  
• reoxidised NAD can now accept more H atoms from glucose during glycolysis

yeast = facultative anaerobe- can live without oxygen but killed when conc ethanol 15%

• rate growth faster under aerobic conditions
• aerobic conditions to start w/ & then placed in anaerobic to undergo alcoholic fermentation

Involves e carriers embedded in inner membrane (folded cristae = large SA e carriers & ATP synthase enzymes)

Reduced NAD + FAD reoxidised = donate H atoms split into protons/electrions = e carriers

First e carrier accept electrons from reduced NAD = NADH - coenz Q reductase (aka NADH dehydrogenase)

Protons go into solution in matrix

• each e carrier (protein complexes arranged in etc) = enzyme associated w/ cofactor (nonprotein haem groups w/ iron atom)
• cofactor accept & donate e bc iron atoms reduced gain e to Iron(II) / oxidised lose e to Iron(III); are oxidoreductase enzymes
• some e carriers have coenzyme pumps protons from matrix to intermembrane space
• inner membrane impermeable small ions, protons accumulate in space = proton gradient

ATP synthase enzymes (aka stalked particles)- large & protrude from inner membrane into matrix & allow protons pass through them

• protons flow down proton gradient, through ATP synthase enzymes, from space to matrix (chemiosmosis)
• force of flow drives rotation of part of enzyme allows ADP + Pi = ATP

Coenzyme FAD = reduced FAD in Krebs tightly bound to dehydrogenase embedded membrane

• H atoms accepted by FAD don't get pumped into space, pass back to matrix

ETC- electron passed along chain e carriers & donated to molecular oxygen (final e acceptor)

~ chemiosmosis

• as e flow along ETC energy released + used by coenzymes associated w/ carriers pump protons across to intermembrane space
  
  
• builds up proton/pH/electrochem gradient so PE builds up in space
  
• H ions can't diffuse lipid part inner membrane but can through ion channels (associated w/ ATP synthase) flow of ions = chemiosmosis
  
  

~ oxidative phosphorylation (formation ATP by ADP + Pi in presence oxygen)

• as protons flow through ATP synth enzyme drives rotation of part of enzyne = ADP + Pi = ATP
  
• e passed from last e carrier to molecular oxygen (final e acceptor)
  
• H ions also join so oxygen reduced to water; 4H + 4e + O2 = 2H2O

pyruvate from Glycolysis transported across inner & outer mitochond. membrane to matrix

- pyruvate decarboxylated + dehydrogenated w/ use pyruvate dehydrogenase & carboxylase

- removal of carboxyl group eventually becomes carbon dioxide

- NAD accepts H atoms = NADH

- CoA acceps acetate = acetyl CoA which carries acetate to Krebs Cycle

Note:

• 0 ATP produced
• 1 NADH made per pyruvate 
• 2 NADH made per glucose molecule

ATP - phosphorylated nucleotide 'universal energy currency'

High-energy intermediate compound, found in prokaryotes & eukaryotes

Contains:

• adenosine (adenine + ribose)
• 3 phosphate groups
  
  

Hydrolysed to ADP & Pi releasing 30.6 kJ energy per mol

Energy immediate available to cells in small, manageable amounts so won't damage + waste

Occurs in many small steps w/ energy each step joining ADP + Pi = ATP

Hydrolysis ATP coupled w/ synthesis reaction ie. proteins which require energy where energy released from hydrolysis = immediate source energy for these biolog processes

Mitochondria- organelles found in eukaryotes & site of link reaction, Krebs & oxidative phospho

• inner & outer phospholipid membrane = envelope
• outer = smooth
• inner = folded into cristae = large SA
  
  

• 2 membranes enclose & separate compartments within
• between membranes = intermembrane space
• matrix enclosed by inner membrane; semi-rigid + gel-like consists of mix proteins, lipids, mitochondrial DNA & ribosomes + enzymes
  
  

• rod-shaped/thread-like mostly 0.5-1.0µm diameter & 2-5µm long but larger in athletes
• metabolically active cells = more longer + densely packed cristae = more ETC + ATP synthase
• can be moved around by cytoskeleton + some permanently positioned near site high demand

Respiration- process whereby energy stored in complex organic mole. used make ATP

Energy- the ability to do work

Anabolic- reactions build large molecules from smaller ones

Catabolic- larger molecules broken down to smaller

Energy:

• exists as potential & kinetic energy
• molecules that move = KE = diffuse down conc grad
• large molecules = chemical portential energy
• can't be made/destroyed & measured in joules w/ lots of forms

Energy needed to drive biolog. processes

Reactions occur in cells = metabolism

Matrix (link reaction/Krebs) contains:

• enzymes catalyse stages reaction
• molecules of NAD
• oxaloacetate- accepts acetate from link reaction
• mitochondrial DNA- code some mitochondrial enzymes/proteins
• mitochondrial ribosomes- proteins assembled

Outer Membrane

• phospholipid composition contains proteins- channel for ions, carrier for large+ enzymes

Inner Membrane

• differ lipid composition from outer
• impermeable most small ions including Hydrogen
• folded into many cristae- increase SA
• embedded electron carriers & ATP synthase enzymes

4 stages respiration; only glycolysis occurs in anaerobic conditions

• first 3 stages H atoms removed oxidation reactions catalysed by dehydrogenase 
• coenzymes help catalyse oxidation/reduction reactions
• H atoms combine w/ coenzymes (NAD) carry them & later split into H ions & e
• Delivering H to cristae reoxidises coenzymes so combine w/ more H atoms
• OILRIG; + reactions are coupled, 1 oxidised other reduced

Nicotinamide Adenine Dinucleotide (NAD)

• Organic, non-protein aids dehydrogenase carry out oxidation reactions
• Made of 2 linked ribose, adenine & 2 phosphate groups
• 1 contains adenine w/ other contains nicotinamide ring accepts H atoms
• When accepts 2 H atoms w/ e = reduced & loses = oxidised

Coenzyme A (CoA)

• Made from panthothenic aid, adenosine, 3 phosphate groups & cysteine
• Carry ethanoate groups from pyruvate to Krebs cycle also acetate group from a/f acids

1. Acetate offloaded from CoA & joins w/ 4C oxaloacetate forming citrate

2. Citrate decarbox & dehyd to 5C where pair H atoms accepted produce NADH 

3. 5C decarbox & dehyd to 4C where pair H atoms accepted produce NADH

4. 4C converted to another 4C & ADP phosphorylated to ATP

5. Second 4C converted to another 4C where pair H atoms removed to become reduced FAD

6. Third 4C dehyd & regenerates to oxyaloacetate where another NADH made

Note:

• 1 turn of cycle for 1 pyruvate so each glucose molecule = 2 turns so double products
• each molecule glucose; 6 NADH, 2 reduced FAD, 4 carbon dioxide & 2 ATP