Chapter 9: Glycolysis & Cellular Respiration
Redox reactions:
- Oxidation: Loses Electrons and is Oxidized LEO
- Reduction: Gains Electrons and is Reduced GER
- Transfer of electrons releases energy stored in organic molecules
- This released energy is used to synthesize ATP
In cellular respiration glucose is oxidized to become carbon dioxide. Oxygen is reduced to
become water
Cellular Respiration: Includes aerobic and anaerobic
- Glucose + 6 oxygen → 6 carbon dioxide + 6 water + ATP
- Glucose and oxygen are broken down in steps
- Electrons are transferred to NAD+
- NAD+ functions as an oxidizing agent (meaning it is reduced, so electrons are
added to it)
- Each NADH (reduced form of NAD+) represents stored energy that is used to
synthesize ATP)
- NADH passes the electrons to the electron transport chain
- O2 is electronegative and pulls electrons down the chain in an energy yielding
tumble
Cellular Respiration: Stages
1. Glycolysis - glucose → pyruvate
2. Citric Acid Cycle - coA + oxaloacetate→ citrate, citrate → oxaloacetate
3. Oxidative phosphorylation: ETC and chemiosmosis
Glycolysis
- “Sugar splitting”
- Glycolysis occurs in the cytosol and makes ATP through substrate level
phosphorylation
, - It harvests chemical energy by oxidizing glucose to two molecules of pyruvate
- Two major phases: energy investment phase, energy payoff phase
- Energy investment phase
- Starts out with glucose and uses 2 atp to ultimately for dihydroxyacetone
phosphate and 2 G3P
- Blanks are both ATP to ADP + P
- Energy Payoff phase
- Each G3P makes one ATP and one NADH and converts to pyruvate
- Blanks are NAD+ to NADH and then ADP to ATP
- Does not need oxygen
- Generates ATP and NADH and does not release CO2
Enzymes: KIK AID KMEK
Kinase breaks down/makes ATP
Dehydrogenase turns NAD+ into NADH
Fermentation
- Occurs after glycolysis
- Anaerobic process
- Cells produce ATP without oxygen
- It regenerates NAD+ that can be used again in
glycolysis
- Occurs in cytosol
- Uses substrate level phosphorylation
Alcohol Fermentation
- Pyruvate is converted to ethanol
- One ethanol and one CO2 for every pyruvate
- Releases CO2 and NAD+ and alcohol
Lactic Acid Fermentation
- Forms NAD+ and lactate
- Human muscle cells use lactic acid fermentation to generate ATP during exercise when
O2 is scarce
Obligate anaerobes: carry out fermentation or anaerobic respiration and cannot survive in the
presence of O2
Facultative anaerobes: can survive using either fermentation or cellular respiration
Pyruvate Oxidation
- Pyruvate enters the mitochondria and is oxidized into acetyl CoA which enters the citric
acid cycle
- Oxidizes pyruvate
Redox reactions:
- Oxidation: Loses Electrons and is Oxidized LEO
- Reduction: Gains Electrons and is Reduced GER
- Transfer of electrons releases energy stored in organic molecules
- This released energy is used to synthesize ATP
In cellular respiration glucose is oxidized to become carbon dioxide. Oxygen is reduced to
become water
Cellular Respiration: Includes aerobic and anaerobic
- Glucose + 6 oxygen → 6 carbon dioxide + 6 water + ATP
- Glucose and oxygen are broken down in steps
- Electrons are transferred to NAD+
- NAD+ functions as an oxidizing agent (meaning it is reduced, so electrons are
added to it)
- Each NADH (reduced form of NAD+) represents stored energy that is used to
synthesize ATP)
- NADH passes the electrons to the electron transport chain
- O2 is electronegative and pulls electrons down the chain in an energy yielding
tumble
Cellular Respiration: Stages
1. Glycolysis - glucose → pyruvate
2. Citric Acid Cycle - coA + oxaloacetate→ citrate, citrate → oxaloacetate
3. Oxidative phosphorylation: ETC and chemiosmosis
Glycolysis
- “Sugar splitting”
- Glycolysis occurs in the cytosol and makes ATP through substrate level
phosphorylation
, - It harvests chemical energy by oxidizing glucose to two molecules of pyruvate
- Two major phases: energy investment phase, energy payoff phase
- Energy investment phase
- Starts out with glucose and uses 2 atp to ultimately for dihydroxyacetone
phosphate and 2 G3P
- Blanks are both ATP to ADP + P
- Energy Payoff phase
- Each G3P makes one ATP and one NADH and converts to pyruvate
- Blanks are NAD+ to NADH and then ADP to ATP
- Does not need oxygen
- Generates ATP and NADH and does not release CO2
Enzymes: KIK AID KMEK
Kinase breaks down/makes ATP
Dehydrogenase turns NAD+ into NADH
Fermentation
- Occurs after glycolysis
- Anaerobic process
- Cells produce ATP without oxygen
- It regenerates NAD+ that can be used again in
glycolysis
- Occurs in cytosol
- Uses substrate level phosphorylation
Alcohol Fermentation
- Pyruvate is converted to ethanol
- One ethanol and one CO2 for every pyruvate
- Releases CO2 and NAD+ and alcohol
Lactic Acid Fermentation
- Forms NAD+ and lactate
- Human muscle cells use lactic acid fermentation to generate ATP during exercise when
O2 is scarce
Obligate anaerobes: carry out fermentation or anaerobic respiration and cannot survive in the
presence of O2
Facultative anaerobes: can survive using either fermentation or cellular respiration
Pyruvate Oxidation
- Pyruvate enters the mitochondria and is oxidized into acetyl CoA which enters the citric
acid cycle
- Oxidizes pyruvate
