Glycolysis + Pyruvate Oxidation: 4.1 + 1/2 4.2

Photosynthesis → ATP

Photosynthesis:

plant use light energy to convert CO2 & H2O to organic molecules (ex. glucose)

• release 02

ATP genration:

energy taken form organic molecules through oxidization & used to make ATP

Aerobic cellular respiration

Extract energy from organic molecules (food) in the presence of oxygen → ATP

• In most eukaryotes & some prokaryotes

Aerobic Cellular respiration equation:

C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP

• ∆G = -2870 KJ/mol

Obligate aerobe def.

organism that cannot live without oxygen

• Most eukaryotes

4 Stages of aerobic cellular respiration:

1. Glycolysis

2. Pyruvate oxidization

3. Citric acid cycle

4. electron transfer and oxidative phosphorylation

What does each step involve?

Transfer of free energy to make ATP in 1 of 2 ways:

1. Substrate-level phosphorylation

2. Oxidative phosphorylation

Substrate-level phosphorylation:

Formation of ATP by direct transfer of a phosphate group from a substrate to ADP

Oxidative phosphorylation:

ATP made using energy transferred indirectly from a series of redox reactions

FInal e- acceptor in an aerobic reaction:

oxygen

Glycolysis:

series of reactions where glucose is broken down to 2 pyruvate + energy released IN CYTOSOL

• ATP (by substrate-level phosphorylation) & NADH made

Pyruvate Oxidization:

Pyruvate oxidized by NAD+ → CO2 (waste) + NADH, and an acetyl group (attached to coenzyme A before → acetyl-CoA)

IN MITOCHONDRIA MATRIX

Citric acid cycle:

Acetyl-CoA molecules enter a metabolic cycle where it is completely oxidized to CO2

• ATP (by substrate-level phosphate), NADH, & FADH2 made

IN MITOCHONDRIA MATRIX

Electron transport & oxidative phosphorylation

NADH & FADH2 are oxidized

hydrogen passed form oxidizing agent to another until transferred to oxygen → make H2O

• free energy release used to make ATP (via oxidative phosphorylation)

IN INNER MITOCHONDRIA MEMBRANE

Mitochondrial matrix responsible for:

• citric acid cycle

• pyruvate oxidation

Mitochondrial inner membrane responsible for:

• e- transport

• majority of ATP synthesis

2 processes to make ATP w/out oxygen:

1. Anaerobic respiration

2. Fermentation

Used by prokaryotes and some protists

Anaerobic respiration

Process that uses a final inorganic oxidizing agent (except oxygen) to make energy

Fermentation

Process that uses an organic compound as the final oxidizing agent to make energy

General common fermentation formula

C6H12O6 -> 2CH3CH2OH + 2CO2

• ∆G = -218KJ/mol → ATP

Obligate anaerobic

Organisms that cannot survive in oxygen

• ex. Trichonympha (protist) lack mitochondria & use fermentation

Facultative anaerobic

Organisms that can survive w/ or w/out oxygen

• ex. yeast or E.coli

CHAP 4.2

CHAP 4.2

How is glycolysis the most fundamental and ancient?

1. Universal → found in all organisms

2. Does not require oxygen

3. Happens in cell cytosol and includes soluble enzymes

What is involved in glycolysis & where?

10 sequential enzyme-catalyzed reactions in cytosol, anaerobic stage

1. 5 energy investment reactions

2. 5 energy payoff reactions

What is produced during glycolysis?

2 pyruvate molecules (3-C), 4 ATP, and 2 NADH,

• Net ATP: 2 ATP

Glycolysis equation w/input and output

glycolysis reaction 1:

Phosphate added to glucose

• ATP lose phosphate group & turn to ADP. The phosphate attaches to glucose and becomes glucose-6-phosophate w/ help of hexokinase

(phosphorylation reaction)

glycolysis reaction 2:

Isomerization

• glucose-6-phosphate rearranged to isomer fructose-6-phospphate w/phosphoglucomutase

(isomerization reaction)

glycolysis reaction 3:

2nd phosphate added

• another ATP lose phosphate (turn to ADP) that attaches to fuctose-6-phosphate to make fructose-1,6-biphospshate

• helped by phosphofructokinase

(phosphorylation reaction)

glycolysis reaction 4:

Split into 2 molecules

• fructose-1,6-biphospphate slept into 2 and becomes glyceraldehyde-3-phospshate (G3P) & dihydroxyacetone phosphate (DHAP)

• helped by aldolase

(lysis reaction)

glycolysis reaction 5:

isomerization

• DHAP unstable and converted to G3P w/ help of triosephosphate isomerase, total 2 G3P going to reaction 6

(isomerization reaction)

glycolysis reaction 6:

reduction of NAD+ G3P → 1,3-biphosphoglycerate

• 2e- & 2p removed form G3P, energy released is trapped by inorganic phosphate from cytosol that gets attached

• 2e- & 1p accepted by NAD+ turning into NADH , other p released into cytosol

• helped by triosephosphate dehydrogenase

(redox reaction)

glycolysis reaction 7:

1st ATP made → 1, 3 - biphosphoglycerate become 3-phosphoglycerate

• one phosphate of 1,3-biphosphoglycerate transferred to ADP

• ATP made

• helped by phosphoglycerate kinase

(substrate-level phosphorylation reaction)

glycolysis reaction 8:

3-phosphoglycerate rearranged, phosphate group at 3-C move to 2-C to make 2-phosphoglycerate

• helped by phosphoglucomutase

(mutase reaction → shifting chem. group to another in same molecule)

glycolysis reaction 9:

Water loss

• e- removed form one part of 2-phosphoglycerate & delivered to another molecule part of molecule

• energy lost is retained by product phosphoenolpyruvate (PEP)

• water lost

• helped by enolase

(redox reaction)

glycolysis reaction 10:

2nd ATP produced

• last phosphate group of phospoenolpyruvate removed and transferred to ADP to make ATP & pyruvate

(Substrate-level phosphorylation reaction)

Net equation of glycolysis

glucose + 2 ADP + 2Pi + 2NAD+ → 2 pryruvate + 2ATP + 2NADH + 2H+

4 key points from glycolysis:

1. 2ATP consumed in reaction increases the free energy of the chemicals in the glycolytic pathway

2. Glucose is partially oxidized, the p.e in the pyruvate is less than one glucose

3. Substrate-level phosphorylation includes an enzyme that transfers a phosphate group to the ADP to make ATP

4. water not included in equation they are consumed inthe gycolysis cycle again for hydrolysis of 2ATP → 2ADP + 2Pi

Energy in 2 moles of ATP?

62 KJ

Complete energy released by complete oxidation of one glucose molecule?

2870KJ

How much free energy is converted to ATP in glycolysis?

62KJ/2870KJ = 2.2% → energy conversion efficiency

• % return is low

Energy stored in:

2 pyruvate & 2 NADH

How much free energy remains in pyruvate after glycolysis?

75% in one glucose molecule

what happens to glucose in pyruvate oxidation & citric acid cycle?

extract remaining free energy in pyruvates where more ATP and e- carriers NADH & FADH2 are formed

• carbon releases CO2 (waste) when remaining glucose completely oxidized

Pyruvate oxidation (Pyruvic acid oxidation): Membrane transfer

must enter inner & outer membrane of mitochondria to reach matrix

• Enter outer membrane by large pored that via diffusion

• Enter inner membrane by pyruvate-specific carriers

What happened when pyruvate enter the matrix?

converted to acetyl group

• a temporary Sulfur atom on a CoA (Coenzyme A) is bond to pyruvate → acetyl-CoA complex

How is pyruvate converted to acetyl-CoA?

1. Decarboxylation reaction occur

• a carboxyl group (COO-) removed form pyruvate to form CO2 waste

WHERE 1/3 CO2 EXHALE IS MADE!!

2. Oxidation of 2-C remaining making an acetyl group

   • dehydrogenation reaction transfer 2e- & 1p to NAD+ (making NADH) & 1p released into solution

Last step of pyruvates being converted to acetyl-CoA?

acetyl group react with sulfur atom of coenzyme A to make acetyl-CoA which carries the 2-carbon acetyl group to the Krebs cycle

• after CoA molecule gets released and cycle repeats

Decarboxylation reaction def.

a chemcial reaction that removes a carboxyl group to form CO2

Dehydrogenation def.

The removal of a hydrogen atom from a molecule

Net reaction of pyruvate oxidation:

2 pyruvate + 2NAD+ + 2CoA → 2acetyl-CoA + 2NADH + 2H+ + 2CO2