Question

Metaphase is not characterized by (a) Complete condensation of chromosome (b) Alignment of chromosome on metaphase plants (c) Attachment of spindle fibre to kinetochore (d) Splitting of chromosome

Short answer

Option (d) Splitting of chromosomes, is not a characteristic of metaphase.

Step-by-step solution

Identify the process

Realise that the question is referring to characteristics of metaphase during cell division. Metaphase is one of the stages of mitosis in eukaryotes and meiosis in sexually reproducing organisms.

Analyze the statements of the options

After understanding what process is being referred to, go through each of the options in the question. Option (a) Complete condensation of chromosome, (b) Alignment of chromosome on the metaphase plate and (c) Attachment of spindle fibre to kinetochore, are all events that occur in metaphase.

Dismiss the false statement

Statement (d) Splitting of chromosomes, happens later in anaphase not metaphase. Therefore, this is the statement that is not characterized by metaphase.

Key concepts

Condensation of Chromosomes

During metaphase, chromosomes are fully condensed. This is a crucial step because chromosomes need to be easy to separate later. When we say chromosomes are condensed, we mean they have coiled up tightly into their most compact structure.
This coiling up makes them visible under a microscope, which wasn't the case earlier in the cell cycle. The process of condensation involves proteins known as histones, which help wind the DNA into neat, compact units called chromosomes.
This tight packaging is important for several reasons:

• It protects the DNA from damage during cell division.
• It ensures an efficient separation of chromosomes into daughter cells.
• It aids in the proper alignment and segregation of chromosomes.

By being tightly packed, chromosomes are less likely to get tangled up or broken as they move around during cell division.

Alignment of Chromosomes

Alignment of chromosomes is a hallmark of metaphase, where they line up in the middle of the cell. This alignment happens on an imaginary line called the metaphase plate.
The purpose of this alignment is to ensure that each daughter cell receives an identical set of chromosomes. It is like setting up a queue to make sure there are no mistakes during separation.

• All chromosomes have found their partners, or homologous pairs, which they align with.
• Each chromosome takes its position in the middle facing opposite poles.
• This precise arrangement prepares them for the next phase, anaphase, where they are pulled apart.

Without this orderly line-up, cells could end up with too few or too many chromosomes, leading to genetic disorders. Hence, proper chromosome alignment is vital for accurate genetic information transfer.

Spindle Fibre Attachment

In metaphase, spindle fibers attach to chromosomes at a region called the kinetochore. The spindle fibers are like ropes reaching out from opposite ends of the cell. Their job is to grab onto the chromosomes and hold them secure.
Each chromosome attaches to spindle fibers from each pole, ensuring that when they pull, each chromosome is evenly divided.
This attachment is crucial for:

• Stabilizing chromosomes so they stay in position on the metaphase plate.
• Preparing for the chromosomes to be pulled apart during anaphase.
• Ensuring equal division of chromosomes so that each daughter cell ends up with the correct number.

If spindle fibers do not attach properly, this can lead to errors in chromosome separation, which might result in cell division errors or diseases such as cancer. Proper spindle fiber attachment is key to a successful cell division.