Chapter 9 - Intro to Cells Met

Metabolism of glucose

C6H12O6 + 6O2 → 6CO2 + 6H2O + free energy

• tons of potential energy

• breaks down little by little thorugh pathways

• ATP produced from free energy

Metabolic pathways

1) Glycolysis → occurs in cytosol

2) cytoplasm does not regulate O2

3) ends with 2 pyruvate (3 carbon) + some energy

4a) WITH O2 (Cellular Respiration)

• 6CO2 produced and LOTS OF ATP (32)

• occurs in mitochondria

• complete oxidation of glucose

4b) WITHOUT O2 (fermentation)

• occurs in cytosol

• lactic acid (2 carbons) or alcohol (2 carbons) produced

• little ATP produced (2)

• incomplete oxidation of glucose + organic molecule (2 or 3 Carbons)

Glycolysis & cellular respiration

Occurs in mitochondria, pathway called glycolysis:

1) glucose

2) TWO pyruvate (3 carbons each)

3) pyruvate oxidation

4) citric acid cycle

5) electron transport chain

Glycolysis & fermentation

occurs in the cytosol, pathway called glycolysis:

1) glucose

2) TWO pyruvate (3 carbons each)

3) fermentation

4) Lactic acid or alcohol

Two ways of making ATP

1) substrate level phosphorylation

• enzyme makes the ATP

2) Through redox reactions:

• glucose has all the electrons and energy

• gives away the electrons and energy

• mobile electron carrier co-enzyme

  • gives H to NAD+ to become NADH

  • NADH is reduced, has all the electrons and energy from the glucose

• O2 → last acceptor of electrons

  • oxygen accepting electron releases a lot of energy

Redox Reactions

Transferring electrons from one susbtance to another

Reduction: gaining electrons or H

Oxidation: Losing electrons or H

Reactant that is reduced is the oxidizing agent, and vice versa

Glycolysis Divided into 2 Stages

1) Energy investing

• use 2 ATP

2) Energy harvesting

• make 4 ATP (substrate level phosphorylation)

• 2 NADH → lots of energy that will go into cellular respiration to make ATP

• Net Gain:

  • 2 pyruvate (3 carbon each)

  • 2 ATP

  • 2 NADH

Cellular Respiration: Pyruvate Oxidation

• occurs in the matrix of the mitochondria

• pyruvate + NAD → Acetyl-CoA + CO2 + NADH (holds energy)

• Net gain:

  • 2 Acetyl-CoA (2 carbons)

  • 2 CO2

  • 2 NADH

Parts of the mitochondria

• Matrix (the inside)

• Inner membrane (the lining of the matrix)

• Inter membrane space (space between matrix and outer membrane)

• Outer membrane

Cellular Respiration: Citric Acid Cycle

Break down the molecule completely (All carbons become CO2, all energy becomes NADH, FADH, or ATP)

• Per cycle (1 molecule of glucose) yields:

  • 2 CO2

  • 3 NADH

  • 1 FADH

  • 1 ATP (produced by substrate level phosphorylation)

• Net gains:

  • 4 CO2

  • 6 NADH

  • 2 FADH

  • 2 ATP

Pathway Order

1) Glycolysis

• start with glucose molecule in the cytosol, no O2 used yet

• 2 pyruvate molecules (3 carbons each)

• 2 ATP & NADH

2) Pyruvate Oxidation

3) Citric Acid Cycle

4) Electron Transport Chain + Chemiosmosis