Cell Respiration: Processes and Pathways

Cell respiration

To convert the energy stored in glucose into ATP

Important energy molecule generated by cell respiration

ATP

Aerobic respiration

Requires oxygen

Anaerobic respiration

Makes lactic acid as a waste product

Aerobic respiration ATP production

Makes more ATP

Aerobic respiration waste products

Makes CO2 and H2O as waste products

Summary equation for aerobic cellular respiration

Glucose + Oxygen gas + ATP building blocks -> Carbon dioxide + Water + Energy

O2 required per glucose

6

CO2 and water generated per glucose

6 CO2 and 6 water

OIL RIG

Oxidation is loss and Reduction is gain

What is lost/gained in oxidation and reduction

Electrons, hydrogen, and energy

NAD+ → NADH

Reduction

FADH2 → FAD

Oxidation

Glucose (C6H12O6) → CO2

Oxidation

Role of electron carriers NAD+ and FAD

They pick up electrons and hydrogen and take them to the electron transport chain

Glycolysis location

Cytoplasm

Net ATP made by glycolysis

2 ATP

Carbon loss during glycolysis

No

Transition reaction location

Mitochondrion

ATP made during the transition reaction

Zero

Carbon loss during transition reaction

Two carbons

CO2 lost per glucose

2

Citric acid cycle location

Mitochondrion

ATP made during the citric acid cycle

2 ATP

ATP made per glucose molecule in citric acid cycle

2

ATP made per Acetyl Co-A molecule

1

CO2 lost during the citric acid cycle

Four carbons

Electron carriers loaded during the citric acid cycle

NADH and FADH2

Electron transport chain location

Mitochondrion

ATP made by the electron transport chain

Yes

ATP range made by the ETC

32 or 34 ATP

CO2 created by the ETC

No

Waste product created by the ETC

Water

Major aspects of glycolysis

6 carbon glucose is split into 2 3 carbon molecules called pyruvic acid

Why ATP is required for glycolysis

To start the chemical reaction by splitting the 6 carbon glucose into 2 molecules with 3 carbons

End products of glycolysis

2 NADH, 2 ATP, 2 pyruvic acid

Net gain of ATP from glycolysis

2 ATP

Electron carrier loaded during glycolysis

NADH

Transition reaction products

2 CO2, 2 NADH, 2 Acetyl-CoA

Waste product produced in transition reaction

CO2

Conversion in transition reaction

3 carbon pyruvic acid is changed to 2 carbon acetyl Co A

Electron carrier loaded during transition reaction

NADH

Link between glycolysis and citric acid cycle

By converting the pyruvate into the molecule that starts the citric acid cycle

ATP made by transition reaction

No

Products of the Citric Acid Cycle

4 CO2, 6 NADH, 2 FADH2, 2 ATP

Why is it called a cycle?

Because we start with this 4 carbon molecule, oxaloacetate, and then we end up with that same molecule after it goes through the cycle

Carbon Molecule Formation

At the start of the cycle the 4 carbon acceptor molecule binds to 2 carbon acetyl CoA forming a 6 carbon molecule called citric acid.

Electron Carriers Loaded

NADH and FADH2

ATP Produced per Acetyl-CoA

1

ATP Produced per Glucose Molecule

2

CO2 Produced per Acetyl CoA

2

CO2 Produced per Glucose Molecule

4

Copies of the ETC

Many copies

Hydrogens Pumped Location

Across the inner mitochondrial membrane

Proton Gradient Creation

Hydrogens are pumped across the inner membrane and end up in the intermembrane space

Path for Hydrogens

They have to pass through the enzyme ATP synthase.

Energy Conversion in ATP Synthase

As the hydrogens pass through the ATP synthase turbine, the mechanical energy is turned into chemical energy which is stored in ATP.

ATP Made per Glucose at the ETC

32-34 ATP

Waste Product of ETC

Water

Energy Molecule Created by ETC

ATP

Electron Acceptor at the End of ETC

Oxygen

Combination to Form Water

Hydrogen, oxygen and electrons combine to form: Water

Why ETC Cannot Make ATP Without Oxygen

If there is no oxygen there is no electron acceptor. The ETC cannot accept any new electrons if the old ones are still there.

ATP Made per Glucose by Anaerobic Respiration

2 ATP

Why Anaerobic Respiration Produces Lactic Acid

We need to empty the electron carrier NAD+ so that we can run the next round of glycolysis.

Electrons Removed from NADH

When pyruvic acid turns into lactic acid, electrons are removed from NADH turning it back into NAD+.

Cramps Caused by Lactic Acid

When lactic acid builds up inside a muscle it causes a pain called cramps.

Equation for Fermentation

Alcohol fermentation: Glucose -> Ethanol + 2 CO2 + 2 ATP | Lactic acid fermentation: Glucose -> Lactic acid + 2 ATP

Waste Products of Fermentation

CO2 and ethanol in alcohol fermentation | Lactic acid in lactic acid fermentation

Why Pyruvic Acid Turns into Ethanol

Yeast needs to empty the electron carrier NAD+ so that it can run the next round of glycolysis.

Location of Fermentation in Yeast Cell

Cytoplasm

Why Yeast Makes Bread Rise

CO2 gas is released during fermentation.

Oxygen Presence When Life Started

No

Mitochondria in Archae Bacteria

No

Organic Molecules for ATP Production

No, carbohydrates are not the only organic molecules that can be used to make ATP.

Other Molecules for ATP Production

Fats and proteins