Problem 107 - Objective Biology for NEET

Question

Assertion: Metabolic reactions can be demonstrated outside the body in cell free systems. Reason: An isolated metabolic rection performed in test tube is neither living nor non-living.

Step-by-Step Solution

Answer

The provided assertion is correct and the reason is also correct. Metabolic reactions can indeed occur outside the body in cell-free systems, and these reactions are neither classified as living or non-living.

Step 1: Understanding Metabolic Reactions

Metabolic reactions are the processes that your body, or the cells in your body, do to maintain life. These might involve conversion of food to energy, elimination of waste materials, etc. These are chemical reactions, and it is possible to perform chemical reactions outside of their usual biological context (e.g. in a test tube).

Step 2: Cell-Free Systems

A cell-free system is a system where an enzymatic reaction is performed outside the body, often in a laboratory setting. This is made possible by extracting the necessary cellular machinery for a particular reaction from a cell, and introducing these components into a controlled environment.

Step 3: An Isolated Metabolic Reaction

An isolated metabolic reaction can indeed be performed in a test tube, for instance. This arrangement is neither living nor non-living. It does not have the full complexity and responsiveness of a living organism, but it still facilitates biological processes like a living organism would.

Step 4: Linking the Assertion and Reason

The assertion and the reason are linked. Given that in cell-free systems, metabolic reactions can happen outside the body. The cell-free system, a 'test tube reaction,' does not classify as living or non-living, rather it supports the assertion that these reactions can happen outside a living system.

Key Concepts

Cell-Free Systems

Cell-free systems are a fascinating method used in scientific research. They allow for the examination of metabolic reactions and other cellular activities outside a living organism. Imagine taking all the tools a cell uses to perform its functions and moving them into a test tube. Here, scientists can control every aspect of the environment. This includes temperature, pH, and the concentration of substrates and enzymes. By doing so, researchers gain the ability to dissect complex cellular processes.

These systems offer several advantages:

• Controlled environment: Scientists can manipulate conditions far more easily than inside a living organism.
• Reduction of biological variables: Cell-free systems remove the meddle of other cellular processes.
• Reproducibility: Experiments can be repeated with consistent results, which is crucial for hypothesis testing.

Despite these benefits, cell-free systems also have limitations, such as lacking the complexity of whole organisms. However, these systems are invaluable for providing a focused view of specific enzymatic reactions.

Enzymatic Reactions

Enzymatic reactions are the driving forces behind the vast majority of metabolic processes. Enzymes are specialized proteins that act as catalysts, speeding up chemical reactions without being consumed in the process. In any given cell, numerous enzymatic reactions occur to maintain life.

These enzymes lower the activation energy required for reactions, making processes more efficient and feasible at the body’s temperatures.

• Specificity: Each enzyme is specific to a particular substrate or set of substrates.
• Efficiency: Reactions that might take years to occur spontaneously can happen in seconds with enzymes.
• Regulation: Cells can regulate enzymatic activity through inhibitors, activators, or other modifications.

Without enzymes, many essential reactions would occur too slowly to sustain life. In cell-free systems, enzymes play a central role by performing reactions that typically take place within living cells, but now happen in a controlled environment.

Biological Processes

Biological processes are the hallmark of life, encompassing everything from breathing to digestion to brain function. These processes rely on a synchronized orchestration of enzymatic reactions that occur within living organisms. Let's explore how these processes operate.

At the heart of biological processes are metabolic pathways, which consist of step-by-step conversions facilitated by enzymes. Each step in a pathway is catalyzed by a specific enzyme, ensuring efficiency and order. Cell-free systems can isolate an individual step of these pathways for detailed study, thereby improving our understanding of the entire process.

• Metabolic Pathways: Complex sequences of reactions that transform substrates into products.
• Anabolism and Catabolism: Anabolism builds up complex molecules, while catabolism breaks them down.
• Homeostasis: Living systems maintain stability through feedback mechanisms and regulatory processes.

By closely examining these pathways in cell-free systems, researchers can better understand how disruptions in these processes might lead to diseases or how they can be harnessed for biotechnological applications.