Problem 141 - Objective Biology for NEET

Question

Assertion: In mitotic metaphase, morphology of chromosomes can most easily study. Reason: Condensation of chromosomes is completed in this stage.

Step-by-Step Solution

Answer

The assertion is correct; chromosomes' morphology can most easily be studied during the mitotic metaphase stage, as the chromosomes are fully condensed and aligned.

Step 1: Understanding Mitotic Metaphase

In the process of mitosis, metaphase is a stage where the chromosomes align themselves along the metaphase plate, an imaginary line in the middle of the cell. This is after the earlier phase (prophase) where chromosomes have already condensed.

Step 2: Understanding Chromosome Condensation

Chromosome condensation is a process that takes place during prophase, where the loosely held DNA strands condense into compact, visible structures called chromosomes. This condensation makes the chromosomes more maneuverable during the process of cell division.

Step 3: Why Metaphase is Suitable for Studying Chromosomes' Morphology

The completion of chromosome condensation in metaphase means the chromosomes are at their most compact, dense state. This, along with their orderly alignment along the metaphase plate, makes them more visible and easier to study in comparison to other stages of mitosis. The chromatids are distinct and the centromere is clearly visible, allowing for an easy study of chromosome morphology.

Key Concepts

Chromosome Condensation

Chromosome condensation is a vital process during cell division. It transforms loosely coiled DNA into tightly packed chromosomes. This transformation occurs mainly during prophase, the first stage of mitosis.

• Condensation makes the chromosomes more manageable.
• DNA wraps around proteins called histones to form nucleosomes.
• Nucleosomes fold further to create a dense, compact structure called chromatin.

This condensation is critical as it prevents tangling and damage to DNA strands during cell division. By the time cells reach metaphase, chromosomes are fully condensed and ready for accurate distribution into daughter cells. The compact nature of chromosomes at this stage aids in their alignment along the metaphase plate.

Cell Division

Cell division is a fundamental biological process where a single cell divides into two daughter cells. It involves several meticulously coordinated steps: prophase, metaphase, anaphase, and telophase. Among these stages, metaphase plays a key role in ensuring genetic material is evenly distributed.

• Prophase: Chromosomes become visible after condensation.
• Metaphase: Fully condensed chromosomes align at the cell's equatorial plane.
• Anaphase: Chromatids are pulled apart to opposite poles.
• Telophase: Chromosomes de-condense and are enclosed in nuclear membranes.

During metaphase, chromosome alignment is crucial for equal segregation. This orderly positioning is important because it ensures each daughter cell receives an identical set of chromosomes, maintaining genetic consistency.

Chromosome Morphology

The study of chromosome morphology, or their form and structure, illuminates how genetic material is organized and segregated during cell division. Chromosomes during metaphase are particularly suited for morphological studies.

• At metaphase, chromosomes are at their most condensed state.
• Each chromosome is made up of two sister chromatids joined at the centromere.
• This stage provides the clearest view due to their organized alignment.

This organized appearance allows scientists to observe and study details like the length of chromatids, the position of the centromere, and any structural abnormalities. Understanding these characteristics is crucial for identifying chromosomal disorders and conducting genetic research.