Question

If photosynthesizing plants are grown in the presence of \(^{14} \mathrm{CO}_{2},\) is every carbon atom of the glucose that is produced labeled with the radioactive carbon? Why or why not?

Short answer

Yes, every carbon atom in the glucose molecule will be labeled with radioactive carbon because the plant absorbs for photosynthesis.

Step-by-step solution

Understand Photosynthesis

Photosynthesis is the process by which green plants use sunlight to synthesize foods with the help of chlorophyll. The basic formula for photosynthesis converts carbon dioxide and water into glucose and oxygen:

Identify the Use of radioactive carbon in the process

In the process mentioned, is radioactive and is used as a tracer to understand how carbon atoms are utilized in photosynthesis. When plants are grown in the presence of , they take this carbon dioxide in for photosynthesis just like they would with regular .

Analyze the formation of glucose

During photosynthesis, the combines with and sunlight to produce glucose. The equation for the photosynthesis process is: In this process, glucose forms with carbon atoms from carbon dioxide.

Determine the Distribution of Labeled Carbons

Given that is the only source of carbon utilized in the atmosphere for photosynthesizing plants, every carbon atom in the glucose molecule will have come from . Therefore, each carbon atom in glucose has incorporated the radioactive carbon.

Key concepts

Radioactive Carbon Tracing

In the study of photosynthesis, scientists often use radioactive carbon tracers to better understand how carbon atoms are processed and incorporated in plants. Radioactive carbon, such as \(^{14}\text{C}\), is a type of carbon isotope used to trace chemical changes in metabolic pathways.

When \(^{14}\text{CO}_2\) is introduced to a photosynthesizing plant, it gets absorbed just like regular \(\text{CO}_2\). This means every carbon atom within the plant's glucose can be traced back to the radioactive carbon source.

By tracking where these radioactive atoms go, scientists learn specifics about the biochemical processes during photosynthesis. For example, they can determine which intermediate molecules contain the radioactive carbon—essential for understanding the entire photosynthetic process. Using this methodology, researchers have discovered that every carbon atom in a glucose molecule originates from the absorbed \(^{14}\text{CO}_2\).

Glucose Formation

Glucose is the main product of photosynthesis and serves as an essential energy source for plants. The chemical formula for glucose is \(\text{C}_6\text{H}_{12}\text{O}_6\).

During photosynthesis, plants convert carbon dioxide (\({CO}_2\)) from the air and water (\(\text{H}_2\text{O}\)) from the soil into glucose and oxygen using sunlight. The balanced chemical equation for this process is:

\(6{CO}_2 + 6\text{H}_2{O} + \text{light energy} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6{\text{O}_2}\)

In this reaction, each glucose molecule formed contains six carbon atoms, twelve hydrogen atoms, and six oxygen atoms. The incorporation of carbon atoms into glucose happens during the Calvin Cycle, a set of light-independent reactions in photosynthesis. Each carbon atom in glucose can be traced back to its source of carbon dioxide, proving the crucial link between \(C0_2\) and glucose.

Carbon Dioxide Incorporation

Carbon dioxide (\(C0_2\)) incorporation is a fundamental step in the photosynthetic process. During the Calvin Cycle, plants take in \(C0_2\) from the air, which becomes part of the plant's internal carbohydrate molecules through a series of enzymatic reactions.

The first step in the Calvin Cycle is carbon fixation, where \(C0_2\) combines with a five-carbon compound called ribulose bisphosphate (RuBP) with the help of the enzyme RuBisCO. This reaction produces a six-carbon compound, which quickly splits into two molecules of a three-carbon compound known as 3-phosphoglycerate (3-PGA).

Through further reactions in the Calvin Cycle, these compounds are effectively converted into glucose. Because every carbon atom in glucose comes from \(C0_2\), we can determine that radioactive carbon introduced as \(^{14}C0_2\) during photosynthesis ensures that each carbon atom in the glucose produced is labeled with the radioactive isotope. This demonstrates how deeply integrated carbon dioxide incorporation is with glucose formation and the overall photosynthesis process.