Life Sciences - Term 1 - Week 9

Cellular respiration is a metabolic process that converts glucose into ATP, the energy currency of cells. This process occurs in three main stages: glycolysis, the Krebs cycle, and the electron transport chain. Each stage plays a crucial role in breaking down glucose and harnessing its energy for cellular functions.

1. Glycolysis: This anaerobic process occurs in the cytoplasm and breaks down one molecule of glucose into two molecules of pyruvate, producing a net gain of 2 ATP and 2 NADH. 2. Krebs Cycle: Also known as the citric acid cycle, this aerobic process takes place in the mitochondria. It further oxidizes pyruvate, producing carbon dioxide, ATP, NADH, and FADH2. 3. Electron Transport Chain: This final stage occurs in the inner mitochondrial membrane, where electrons from NADH and FADH2 are transferred through a series of proteins, ultimately producing a large amount of ATP and water.

Consider a single molecule of glucose undergoing cellular respiration. Glycolysis produces 2 ATP, the Krebs cycle produces 2 ATP, and the electron transport chain can yield approximately 32-34 ATP. Therefore, the total ATP yield from one glucose molecule can be around 36-38 ATP. This example illustrates the efficiency of cellular respiration in energy production.

As a class, we will fill in a table that lists the reactants and products of each stage of cellular respiration. For example, in glycolysis, the reactants are glucose and 2 ATP, while the products are 2 pyruvate, 4 ATP (net gain of 2), and 2 NADH. Students will work in pairs to complete the table for the Krebs cycle and the electron transport chain.

Students will choose one stage of cellular respiration to research further. They will prepare a short presentation that includes the biochemical processes involved, the significance of this stage, and any relevant diagrams. Presentations will be shared in the next class, allowing for peer learning and discussion.

• To produce glucose
• To convert glucose into ATP
• To release oxygen
• To synthesize proteins

Answer: To convert glucose into ATP

The main goal of cellular respiration is to convert the energy stored in glucose into ATP, which cells use for energy.

• In the mitochondria
• In the cytoplasm
• In the nucleus
• In the endoplasmic reticulum

Answer: In the cytoplasm

Glycolysis occurs in the cytoplasm of the cell, where glucose is broken down into pyruvate.

• Oxygen
• NADH
• Glucose
• ATP only

Answer: NADH

The Krebs cycle produces NADH, ATP, and carbon dioxide as it processes pyruvate.

• NADH
• FADH2
• Oxygen
• Carbon dioxide

Answer: Oxygen

Oxygen acts as the final electron acceptor in the electron transport chain, forming water.

Answer: 2 ATP

Glycolysis produces a total of 4 ATP, but since 2 ATP are used in the process, the net gain is 2 ATP.

Answer: NADH carries electrons to the electron transport chain.

NADH is an electron carrier that transports electrons from glycolysis and the Krebs cycle to the electron transport chain, where they are used to produce ATP.

Answer: ATP, NADH, FADH2, and carbon dioxide.

The Krebs cycle produces ATP, NADH, FADH2, and releases carbon dioxide as a waste product.