Question

State the role or function of each of the following in cell respiration: CO2, glucose, O2, heat, and ATP. (p. 29)

Short answer

Question: Briefly explain the roles of glucose, oxygen, carbon dioxide, ATP, and heat in the process of cellular respiration. Answer: In cellular respiration, glucose acts as the primary fuel source and is broken down to produce ATP, CO2, and water. Oxygen plays a vital role as the final electron acceptor in the electron transport chain, allowing the synthesis of ATP and formation of water. Carbon dioxide is a waste product formed during the Krebs cycle and is exhaled by the organism. ATP is the primary energy currency of cells and is generated to store and transport the chemical energy needed for various cellular processes. Heat is a byproduct of cellular respiration, maintaining the organism's body temperature within an optimal range, especially in endothermic animals.

Step-by-step solution

Understanding Cellular Respiration

Cellular respiration is a set of metabolic reactions and processes that occur in the cells of living organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), which is released as heat. It involves the breakdown of glucose in the presence of oxygen to produce carbon dioxide, water, and energy in the form of ATP.

Role of Glucose in Cellular Respiration

Glucose is the primary fuel source for cellular respiration. It is a simple sugar (monosaccharide) derived from the food we eat. During cellular respiration, glucose is broken down through a series of chemical reactions (glycolysis, Krebs cycle, and electron transport chain), which ultimately produce ATP, CO2, and water.

Role of Oxygen in Cellular Respiration

Oxygen (O2) plays a vital role as the final electron acceptor in the electron transport chain of cellular respiration. During the process, electrons are passed down the chain, creating an electrochemical gradient that drives the synthesis of ATP. Oxygen accepts these electrons, which prevents the electron transport chain from becoming overloaded with electrons, and combines with hydrogen ions to form water.

Role of Carbon Dioxide in Cellular Respiration

Carbon dioxide (CO2) is a waste product of cellular respiration. It is formed during the Krebs cycle, where glucose is further broken down to release energy and create ATP. CO2 is then transported out of the cell and eventually exhaled by the organism as a waste product.

Role of ATP in Cellular Respiration

Adenosine triphosphate (ATP) is the primary energy currency of the cell and is generated during cellular respiration. ATP is produced during glycolysis, the Krebs cycle, and the electron transport chain. It is used to store and transport the chemical energy needed for various cellular processes, including the synthesis of new molecules, transport of materials across the cell membrane, and muscle contraction.

Role of Heat in Cellular Respiration

Heat is a byproduct of cellular respiration. The energy that is released during the process is partly stored as ATP, while the rest is given off as heat. This heat is beneficial for maintaining the organism's body temperature within an optimal range, especially in endothermic (warm-blooded) animals.

Key concepts

Glucose Metabolism

Glucose plays a central role in cellular respiration, serving as the primary fuel source that cells use to produce energy. It is a simple sugar, or monosaccharide, obtained from the digestion of carbohydrates in our diet.

During cellular respiration, glucose undergoes a sequence of chemical reactions starting with glycolysis, followed by the Krebs cycle, and concluding with the electron transport chain. These stages work together to break down glucose into smaller molecules, ultimately extracting chemical energy.

This energy is crucial as it gets converted into ATP, the cell’s energy currency, allowing our cells to perform various functions.

ATP Production

ATP, or adenosine triphosphate, acts like the battery for our cells, providing the energy they need to function. During cellular respiration, ATP is produced through a series of steps.

1. **Glycolysis**: This initial phase occurs in the cytoplasm where glucose is split into two molecules of pyruvate, yielding a small amount of ATP.

2. **Krebs Cycle**: As pyruvate enters the mitochondria, it is further broken down during the Krebs cycle, producing more ATP and several electron carriers.

3. **Electron Transport Chain**: The final phase involves electron carriers delivering electrons to the transport chain, where their energy is used to produce a larger supply of ATP.

Overall, ATP serves as the energy reservoir for processes such as muscle contraction, active transport across membranes, and synthesis of biomolecules.

Role of Oxygen

Oxygen is essential in the process of cellular respiration, especially during the electron transport chain, which is the final step.

Oxygen acts as the ultimate electron acceptor at the end of the electron transport chain. Without it, the chain would get clogged with electrons, halting ATP production.

By accepting electrons, oxygen combines with protons to form water, effectively clearing the path for a seamless flow of electrons. This process drives the proton gradient needed for ATP synthesis, making oxygen indispensable for efficient energy production in cells.

Carbon Dioxide as a Waste Product

Carbon dioxide is a significant waste product generated during cellular respiration. As our cells break down glucose, carbon dioxide is released during the Krebs cycle.

This CO2 exits the cell through diffusion and is eventually carried by the bloodstream to the lungs, where it is expelled when we breathe out.

Its removal is vital not only for maintaining the balance of metabolic reactions but also to prevent the accumulation of excess CO2, which can disturb the body's pH levels and cell function.