Module 5 Intro

Module 5—Photosynthesis and Cellular Respiration

Lesson Summary

 

In this lesson the following essential questions were explored:

• How does the presence of oxygen affect cellular respiration?
• How does aerobic cellular respiration release potential energy from organic compounds?

You are already familiar from previous lessons and science courses that oxygen is required in aerobic respiration. In this lesson you discovered that the specific role of oxygen is to be a final electron acceptor in the electron transport chain. This chain is located in the inner membrane of the mitochondrial matrix. Oxygen accepts electrons from oxidized glucose and combines with hydrogen molecules to produce water. When oxygen is present, 36 molecules of ATP are produced compared to 2 molecules of ATP during anaerobic respiration.

 

The production of ATP occurs through a series of metabolic pathways. In each step of aerobic respiration glucose (or an intermediate carbon molecule) is oxidized and ATP is synthesized through phosphorylation. For every glucose that is completely oxidized, glycolysis produces 2 ATP, the Krebs cycle produces 2 ATP, and the electron transport chain synthesizes the jackpot of 32 ATP molecules. Cells will use the energy to fuel activities such as active transport, muscle contraction, and biochemical synthesis. Since multicellular organisms have high energy demands, it makes sense that these organisms function aerobically.

 

Lesson Glossary

 

acetyl CoA: an oxidized form of glucose

 

FADH2: an important coenzyme produced during Krebs cycle

 

It acts as an electron donor to the electron transport system involved in the production of ATP.

 

Krebs cycle: a metabolic pathway consisting of a series of reactions that break down the end products of glycolysis, producing carbon dioxide and generating a large amount of ATP; also know as the citric acid cycle; named after the 1953 Nobel Prize winning scientist who made the discovery

 

NADH: a high-energy electron carrier

 

It acts as an electron donor to the electron transport system involved in the production of ATP.
 

VO2 max: used to measure how well an athlete is able to use oxygen during an activity: units are mL/kg/min