Problem 64 - Objective Biology for NEET

Question

Spindle fibres are made up of (a) Proteins (b) Lipids (c) Cellulose (d) Pectin

Step-by-Step Solution

Answer

Spindle fibres are made up of Proteins

Step 1: Understand the biological concept of spindle fibres

Spindle fibres are key components of cell division (mitosis and meiosis). They exist to help separate the chromosomes of the cell.

Step 2: Recall spindle fibres composition

Spindle fibres are, by definition, protein structures that form during cell division to segregate chromosomes between daughter cells.

Step 3: Match the knowledge with the options

Given the components listed in the exercise - Proteins, Lipids, Cellulose, Pectin - the correct match considering spindle fibres composition is Proteins.

Key Concepts

Cell Division

Cell division is a fundamental biological process that allows organisms to grow, repair damaged structures, and reproduce. It encompasses two main types: mitosis and meiosis. During cell division, spindle fibers play a crucial role in ensuring that the genetic material, contained within chromosomes, is evenly distributed between the newly formed cells.

This process begins when a parent cell divides to produce two or more daughter cells. In the case of mitosis, this results in two genetically identical daughter cells, each containing the same number of chromosomes as the original parent cell. Alternatively, in meiosis, which is specific to the production of sex cells or gametes, the resulting cells have half the number of chromosomes, contributing to genetic diversity.

Mitosis

Mitosis is a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth. It is divided into several stages: prophase, metaphase, anaphase, and telophase.

Importance of Spindle Fibers in Mitosis

During mitosis, spindle fibers emerge from the cell's centrosomes, attaching to the centromere of each chromosome. These fibers pull the chromosomes apart, ensuring that each new cell receives an exact copy of the genetic material.

This process is critical for growth and repair in multicellular organisms, as well as asexual reproduction in some single-celled organisms. Understanding the role of spindle fibers can shed light on genetic disorders and diseases that arise from cell division errors.

Meiosis

Meiosis, on the other hand, is a specialized form of cell division that reduces the chromosome number by half, creating four haploid cells, each genetically distinct from the parent cell. This type of division is essential for sexual reproduction and occurs in two phases: meiosis I and meiosis II.

Role of Spindle Fibers in Meiosis

Spindle fibers are equally important in meiosis; they ensure accurate segregation of chromosomes during both divisions. Unlike mitosis, meiosis introduces genetic variation through processes such as crossover and independent assortment.

Knowledge of meiosis is fundamental for understanding inheritance patterns, genetic diversity, and the role of spindle fibers in the accurate division of genetic material in the formation of gametes.

Chromosomes

Chromosomes are thread-like structures located within the nucleus of animal and plant cells. They are made of protein and a single molecule of deoxyribonucleic acid (DNA), which is passed from parents to offspring during reproduction.

Structure and Function of Chromosomes

Each chromosome has a constriction point called the centromere, where spindle fibers attach during cell division. Humans have 46 chromosomes, arranged in 23 pairs, while other organisms may have different counts.

Chromosomes carry the genes responsible for hereditary characteristics and are vital for all forms of life. The comprehensive comprehension of chromosomes and their behavior during cell division can illuminate genetic engineering, biotechnology, and cancer research.