Honors Bio - Unit 3, Concept 5

To convert the chemical energy in food (glucose) to chemical energy stored in ATP.

C6H12O6  + 6O2  🡪  6H2O  + 6CO2 + Energy (ATP)

Glucose and Oxygen

CO2 and water as waste products, and the main product is Energy (or ATP)

Aerobic respiration has oxygen to use. Anaerobic respiration doesn't have oxygen to use.

Anaerobic: 2-4 ATP Aerobic: 36-38 ATP

Glycolysis

A stage where glucose breaks down.

It's a 10 step process where the 6-C molecule of glucose is split in half, making 2 3-C molecules called pyruvate.

This stage takes place in the cytoplasm.

This first stage doesn't need oxygen. It is anaerobic.

It produces a net 2 ATP and 2 NADH molecules total.

• Tip: 1 glucose creates 2 NADH, 2 pyruvate molecules, and 4 ATP, but it uses 2 of that ATP to work at all. This means there's a net of 2 ATP.

Reactants: Glucose

Products: 2 ATP, 2 NADH, and 2 pyruvate molecules

ATP, NADH, pyruvate will move on from this stage.

The cell must make a decision on what type of respiration to continue to after it completes this stage.

• If there is O2 present, the cell will go through a 2-step process called aerobic respiration to gain energy.

• If there isn't O2 present, the cell will go through anaerobic respiration, aka fermentation, to gain energy.

The Krebs/Citric Acid Cycle.

This stage’s purpose is to make electron carriers (NADH and FADH2) to move on to ETC.

This stage takes place in the Mitochondrial Matrix.

8-steps of chemical reactions where 2 pyruvate molecules from glycolysis chemically convert to make 2 ATP (and some CO2, NADH, and FADH2) in this cycle.

Pyruvate from glycolysis has converted into acetyl-CoA during the Krebs Cycle. It has now entered the Citric Acid cycle.

• NAD+ and FAD act as electron carriers and become NADH and FADH2, and they carry electrons into the final step.

CO2 is released as a waste product.

This cycle happens 2 times - once per pyruvate.

8 NADH, 2 ATP, 2 FADH2, and 6 CO2 are the products of this cycle.

*Note: The cycle happened twice. Each time it happens, half of these overall products are made. For example, that means 1 ATP and 3 CO2 are made each time.

Electron Transport Chain (ETC) happens after this cycle.

This takes place in the Inner Membrane of the Mitochondria (called cristae).

A series of reactions using electrons & hydrogens carried by NADH & FADH2 - which were both made in the Krebs cycle - happen.

• Oxygen combines with electrons and H+ to make water.

• the enzyme ATP Synthase creates the ATP

34 ATP and water is made during this stage

This stage is so important b/c it makes the most ATP.

NADH, FADH2, oxygen are used as reactants for this stage.

Water and 34 ATP are products of this stage.

Lactic acid and Alcohol Fermentation are the 2 types of this.

This fermentation occurs in some bacteria and animal cells (like our muscles).

Pyruvate from glycolysis converts into lactic acid and 2 ATP.

This fermentation occurs in yeast when there’s no oxygen.

Pyruvate from glycolysis breaks down into alcohol, CO2, and 2 ATP.

Bacteria and animals (like humans!) are examples of organisms that go through this fermentation.

Yeast is an organism (is it? It’s a thing that does, at least) that goes through alcohol fermentation.