Question

Imagine that you breathe in oxygen and it binds to hemoglobin in your blood to form \(\left[\mathrm{O}_{2} : \text { hemoglobin }\right] .\) a. Write a balanced equation for the process. b. The \(\left[\mathrm{O}_{2} : \text { hemoglobin delivers oxygen to your cells. Describe this process. }\right.\) c. Provide evidence that this process is reversible.

Short answer

a. Hb + O₂ ↔ HbO₂; b. O₂ is delivered to cells from HbO₂ in tissues; c. The process is reversible owing to oxygen pressure differences in lungs vs tissues.

Step-by-step solution

Balance the Chemical Equation

The process of oxygen binding to hemoglobin can be represented by the chemical equation \[ ext{Hb} + ext{O}_2 ightleftharpoons ext{HbO}_2\] where Hb is hemoglobin and HbO₂ is oxyhemoglobin. This equation is balanced as it shows one molecule of oxygen (O₂) binding with hemoglobin (Hb) to form one molecule of oxyhemoglobin (HbO₂).

Describe Oxygen Delivery

Oxyhemoglobin (5HbO₂5) travels through the bloodstream to body tissues. In tissues with low oxygen levels (high levels of carbon dioxide), the oxyhemoglobin releases the oxygen, which diffuses into cells for cellular respiration, providing essential energy for the cells.

Evidence of Reversibility

The reversibility of this process can be observed in the ability of hemoglobin to bind oxygen in the lungs and release it in body tissues. The binding and release are driven by the partial pressures of oxygen and carbon dioxide; high oxygen levels in the lungs promote binding, while low oxygen levels in tissues promote release. This dynamic equilibrium is a hallmark of a reversible reaction.

Key concepts

Chemical Equilibrium

Chemical equilibrium is a state in a chemical reaction where the concentrations of reactants and products remain constant over time. This happens because the forward and reverse reactions occur at equal rates. In the context of hemoglobin and oxygen, the chemical equilibrium is represented as follows:\[\text{Hb} + \text{O}_2 \rightleftharpoons \text{HbO}_2\]Here, hemoglobin (Hb) binds with oxygen (O₂) to form oxyhemoglobin (HbO₂). While in the lungs, the high partial pressure of oxygen drives the reaction to the right, favoring the formation of HbO₂. However, in the tissues, where the oxygen concentration is lower, the reaction shifts to the left, favoring the release of oxygen. This is a classic example of chemical equilibrium in biological systems, showcasing a balance between oxygen uptake and release, dependent on environmental conditions within the body.

Cellular Respiration

Cellular respiration is the process by which cells convert oxygen and nutrients into energy, carbon dioxide, and water. Oxyhemoglobin plays a crucial role in delivering oxygen to the cells. When red blood cells pass through the capillaries of tissues with low oxygen concentrations, oxyhemoglobin releases its bound oxygen.The free oxygen then diffuses into cells, where it is used in cellular respiration to produce adenosine triphosphate (ATP), the energy currency of the cell. Here is a simplified equation for cellular respiration:\[\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{energy (ATP)}\]This process is crucial for maintaining the energy balance in cells. Without sufficient oxygen supplied by hemoglobin, cellular respiration would be incomplete, leading to reduced energy production and impaired cell function.

Oxyhemoglobin

Oxyhemoglobin refers to the complex formed when oxygen binds to hemoglobin in the blood. Hemoglobin consists of four subunits, each of which can bind one oxygen molecule, allowing hemoglobin to transport a large amount of oxygen efficiently. As blood flows through the lungs, high oxygen concentrations facilitate the loading of oxygen onto hemoglobin, forming oxyhemoglobin. Once formed, oxyhemoglobin is transported by the bloodstream to tissues and organs requiring oxygen for metabolic activities. In tissues, where carbon dioxide levels are higher and oxygen levels are lower, oxyhemoglobin releases the oxygen it carries. This release is crucial for sustaining cellular respiration in body cells, ensuring they receive enough oxygen to maintain vital functions.

Chemical Reaction Balancing

Balancing a chemical equation ensures that there are the same number of each type of atom on both sides of the equation, reflecting the conservation of mass. For the reaction between hemoglobin and oxygen forming oxyhemoglobin, the balanced equation is:\[\text{Hb} + \text{O}_2 \rightleftharpoons \text{HbO}_2\]Here, one molecule of oxygen (O₂) binds with hemoglobin (Hb) to form one molecule of oxyhemoglobin (HbO₂). Ensuring this equation is balanced is important because it represents the actual stoichiometry of the reaction, confirming that no atoms are lost or created in the process.Proper chemical reaction balancing is fundamental in studying reactions, since it helps to predict the amounts of reactants consumed and products formed. In the case of hemoglobin and oxygen, this understanding aids in comprehending how efficiently oxygen can be transported and utilized in the body.