Biology 12 - respiration

Cellular respirationProvides energy for the cell

Occurs in all cells

Net equation:

glucose + oxygen carbon dioxide + water + energy (ATP)

Occurs as a series of reactions, involving many different enzymes

Involves anaerobic and aerobic reactions

ATP and ADP

• Act as chemical batteries

• Carry and release small amounts of energy

energy

adenosine

phosphateadenosine

ATP

ADP

Anaerobic respiration

• Occurs in the cytoplasm

• Does not need oxygen

• Involves 2 processes – glycolysis and fermentation

Glycolysis

• Glucose is broken down into 2 pyruvate (pyruvic acid) molecules

• Reactions use 2 ATP

• Reactions make 4 ATP

• Net ATP = 2/glucose molecule

FermentationIn animals:

Pyruvate is converted to lactic acid

In plants and fungi:

Pyruvate is converted to ethanol and carbon dioxide

Aerobic respiration

• Occurs in the mitochondrion

• Needs oxygen

• Involves Transition reaction, Krebs cycle and Electron transport chain

• Involves many reactions and enzymes

• Produces 36 ATP

• Waste products are carbon dioxide and water

Structure of mitochondrion

Transition reaction

• Pyruvate attaches to Coenzyme A to form Acetyl Coenzyme A

• Acetyl Coenzyme A enters mitochondrion and releases the pyruvate into the Krebs cycle

• Coenzyme A can also pick up fatty acids and take them into the Krebs cycle

Transition reaction

Krebs cycle

• Occurs in the matrix of the mitochondrion

• A cycle of reactions generates ATP and hydrogen ions (carried by NAD and FAD carriers to electron transport chain)

• Waste product is carbon dioxide

• Produces 2 ATP/glucose molecule

Krebs cycle

Carrier proteins

Carry hydrogen ions to electron transport chains

NAD NADH + H+

FAD FADH2 + H+

Electron transport chain

• Found in the cristae (inner membranes) of the mitochondrion

• ATP is generated as hydrogen ions are passed down the chain

• Oxygen is used up

• Waste product is water

• Produces 34 ATP/glucose molecule

Electron transport chain

Summary of reactions

Comparison of aerobic and anaerobic respiration

Anaerobic Aerobic

Site it occurs cytoplasm mitochondrion

Need for oxygen no yes

Waste products Animals – lactic acid

Plants – carbon dioxide and alcohol

Carbon dioxide and water

Amount of ATP 2/glucose molecule 36 – 38/glucose molecule

Reactions involved

Glycolysis

Fermentation

Glycolysis

Transition reaction

Krebs cycle

Electron transport chain