Biology Chapter 8: Primary Catabolism

Chapter 8 Notes: Primary Catabolism

• Metabolism uses enzymes to break down (catabolize) organic molecules into smaller precursor molecules, which cells then use to build (anabolize) larger molecules.
• Three pathways of primary catabolism: glycolysis, Krebs cycle, and respiratory chain/oxidative phosphorylation.

Glycolysis

• Glycolysis is the first step in all three metabolic strategies.
• Glucose is oxidized into two molecules of pyruvic acid.
• Two molecules of NADH and two of ATP are produced.

Krebs Cycle

• This is part of aerobic respiration.
• Not mentioned in glycolysis.

Respiratory Chain/Oxidative Phosphorylation

• This relies on oxygen.
• Electrons are transported.
• Oxidative phosphorylation involves other oxidized compounds like NO3-, SO42-, and CO3- as final electron acceptors when oxygen isn't present.

Anaerobic Respiration (No Oxygen)

• Includes respiration that does not rely on oxygen and uses specific compounds as final electron acceptors like nitrates, sulfates.

Fermentation

• A type of incomplete oxidation of glucose.
• Does not require oxygen.

Catabolism of Noncarbohydrates

• Complex polysaccharides are broken down into component sugars that can enter glycolysis.
• Lipids are broken down by lipases; fatty acids undergo beta-oxidation to enter the Krebs cycle.
• Proteins are broken down into amino acids by proteases; amino groups are removed through deamination.

General Catabolism

• Catabolic processes occur continuously as long as nutrients are present.
• These processes supply the energy for building complex molecules.

This quiz covers the essential concepts of primary catabolism, including the pathways of glycolysis, the Krebs cycle, and oxidative phosphorylation. Understand how enzymes break down organic molecules and the processes involved in both aerobic and anaerobic respiration.