Problem 95 - Chemistry Matter and Change

Question

Calculate Approximately 38 mol of ATP are formed when glucose is completely oxidized during cellular res- piration. If the heat of combustion for 1 mol of glucose is \(2.82 \times 10^{3} \mathrm{kJ} / \mathrm{mol}\) and each mole of ATP stores 30.5 \(\mathrm{kJ}\) of energy, what is the efficiency of cellular respiration in terms of the percentage of available energy that is stored in the chemical bonds of ATP?

Step-by-Step Solution

Answer

The efficiency of cellular respiration is approximately 41.1%.

Step 1: Determine Total ATP Energy

First, calculate the total energy stored in ATP when 38 mol of ATP are produced. This can be done by multiplying the number of moles of ATP by the energy stored per mole:\[E_{ATP} = 38 \, \text{mol} \times 30.5 \, \text{kJ/mol} = 1159 \, \text{kJ}\]

Step 2: Gather Energy from Glucose Combustion

The given energy from glucose combustion is provided as 2820 kJ per mole. Here, 38 moles of glucose aren't combusted to achieve the ATP yield — rather, approximately one mole provides the heat value before the 38 moles of ATP are considered. So:\[E_{glucose} = 2820 \, \text{kJ/mol}\]

Step 3: Calculate Efficiency

The efficiency of energy conversion in a system can be calculated by dividing the useful energy output by the energy input, then multiplying by 100 to get a percentage. In this case:\[\text{Efficiency} = \left(\frac{E_{ATP}}{E_{glucose}}\right) \times 100 = \left(\frac{1159}{2820}\right) \times 100 \approx 41.1\%\]

Step 4: Conclusion

The efficiency of cellular respiration, in terms of the percentage of available energy from glucose combustion stored in ATP, is about 41.1%. This means that 41.1% of the energy from glucose is effectively captured in the ATP molecules during cellular respiration.

Key Concepts

ATP energy

ATP, or adenosine triphosphate, is the primary energy carrier in biological systems. It stores and provides energy for many cellular processes. This molecule is composed of three phosphate groups, ribose, and adenine. Each bond between phosphate groups contains high amounts of energy.
When a cell needs energy, ATP is broken down into ADP (adenosine diphosphate) and an inorganic phosphate. This breakdown releases energy due to the breaking of the phosphate bond. The energy released is then used to perform various cellular functions like muscle contraction, nerve impulse propagation, and chemical synthesis.

• ATP acts like a rechargeable battery, being converted back to ATP from ADP during cellular respiration.
• The energy density of ATP is about 30.5 kJ per mole.
• In biological terms, ATP serves as the energy currency of the cell.

Overall, ATP is crucial because it helps fuel essential biological activities, allowing cells to maintain life processes effectively.

glucose combustion

Glucose combustion, often referred to as glucose oxidation, is the process of breaking down glucose molecules to release energy. During cellular respiration, glucose is the primary substrate used to generate ATP. This process occurs in several stages, including glycolysis, the citric acid cycle, and oxidative phosphorylation.
The complete combustion of one mole of glucose releases a significant amount of energy, which is estimated to be 2820 kJ. The breakdown of glucose begins in the cytoplasm, with glycolysis splitting glucose into two molecules of pyruvate, followed by further steps in the mitochondria.

• Stages of Glucose Combustion: Glycolysis, Citric Acid Cycle (Krebs Cycle), and Electron Transport Chain.
• The primary goal is to convert glucose into usable energy stored in ATP, carbon dioxide, and water.
• The heat of combustion refers to the total energy released when glucose is completely oxidized.

This process is essential as it forms the foundation for energy production in cells, allowing them to perform normal, daily functions.

energy conversion efficiency

Energy conversion efficiency in cellular respiration refers to the percentage of the potential energy in glucose that is successfully captured in the form of ATP. The efficiency of the conversion during cellular respiration is a critical factor, as it determines how effectively a cell can utilize stored energy.
According to the calculations, only 41.1% of the energy from glucose ends up stored in ATP molecules. The remaining energy is lost primarily as heat. This percentage is determined by comparing the total energy stored in ATP to the energy available from glucose combustion.

• Key Formula: Efficiency = (Energy stored in ATP / Energy from glucose) × 100.
• This process is crucial for determining how well organisms transform food into usable energy.
• Improving efficiency could lead to better energy management in biological and engineered systems.

Understanding energy conversion efficiency helps researchers explore ways to enhance bioenergetics and conservation in metabolic processes.

molecular biology

Molecular biology is the branch of biology focused on the molecular basis of biological activity within the cell. It involves understanding the interactions between the various systems of a cell, including the relations between DNA, RNA, and protein synthesis and regulation.
In the context of cellular respiration, molecular biology examines the biochemical processes that allow cells to harvest energy from nutrients. It provides insights into how enzymes and other molecules facilitate energy transformations during the oxidation of glucose.

• It studies how genetic information is translated into cellular function, particularly in energy production.
• Research in this field helps decode the complex mechanisms behind energy conservation in cells.
• It encompasses crucial studies into enzymes like ATP synthase, which helps in ATP production.

Molecular biology not only helps understand cellular respiration but also lays the foundation for advancements in medical, environmental, and industrial biotechnology applications.