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Module 8 Lesson 3 Progress Check

Prompt

Answer the "M8 L3 Check Your Progress" questions (p214 #1, 2, 3, 5, 6 and Critical Thinking Question below) and submit your answers here.

Response

  1. Summarize the stages of cellular respiration and explain its relationship to body temperature.

    Cellular respiration consists of several stages: glycolysis (splitting glucose into pyruvate), the link reaction (converting pyruvate to Acetyl-CoA), the Krebs cycle (oxidizing Acetyl-CoA to \(CO_2\)), and the electron transport chain (producing ATP from electron transfer). This process releases energy, part of which is heat, contributing to the maintenance of body temperature in warm-blooded organisms.

  2. Identify how many carbons from one glucose molecule enter one round of the Krebs cycle.

    In one round of the Krebs cycle, two carbons from one glucose molecule enter as part of Acetyl-CoA. This is because glucose (6 carbons) is split into two pyruvate molecules (3 carbons each), and each pyruvate loses one carbon before entering the Krebs cycle as Acetyl-CoA.

  3. Explain how high-energy electrons are used in electron transport.

    In the electron transport chain, high-energy electrons from \(NADH\) and \(FADH2\) are transferred through a series of proteins. This transfer generates a proton gradient across the mitochondrial membrane, which drives the synthesis of \(ATP\), the main energy currency of the cell.

  4. Math Connection How many \(ATP\), \(NADH\), and \(FADH2\) are produced in each step of cellular respiration? How is the number of \(ATP\) produced different from the net \(ATP\) available?

    Cellular respiration produces \(ATP\), \(NADH\), and \(FADH2\) at different stages: 2 \(ATP\) and 2 \(NADH\) in glycolysis, 2 \(NADH\) in the link reaction, 2 \(ATP\), 6 \(NADH\), and 2 \(FADH2\) in the Krebs cycle, and approximately 34 \(ATP\) in the electron transport chain. The net \(ATP\) differs from the total produced because some \(ATP\) is used for transporting NADH into mitochondria and other processes.

  5. Compare and contrast the two types of fermentation.

    Alcoholic fermentation, occurring in yeasts, converts pyruvate into ethanol and \(CO_2\), producing 2 \(ATP\) per glucose. Lactic acid fermentation, found in muscle cells and some bacteria, turns pyruvate into lactic acid with the same ATP yield. Both types regenerate NAD+ for glycolysis but differ in their end products and biological contexts.

  6. Cells uses \(ATP\) as a source of energy for cellular processes instead of combusting glucose when the cell needs energy. Why? (Hint: \(C_6H_{12}O_6 \text{ (glucose)} + 6O2 \rightarrow 6CO_2 + 6H_2O\), this process involves breaking down multiple covalent bonds, not just one)

    Cells use ATP for energy instead of direct glucose combustion because ATP provides a more controlled and efficient energy release. Direct combustion of glucose would release energy too rapidly and less efficiently, whereas \(ATP\) allows for gradual and targeted energy release, suitable for diverse cellular processes.