1.2. Describe the process of mitosis

This guide will help you answer 1.2. Describe the process of mitosis.

Mitosis is an essential process that allows cells to divide and produce new, identical cells. This process is crucial for growth, repair, and reproduction in multicellular organisms. It ensures that each new cell receives an identical copy of the genetic material, or DNA, of the original cell. In this explanation, we’ll break down the stages of mitosis, exploring how it works and why it is important.

What is Mitosis?

Mitosis happens in somatic cells — these are any body cells that are not involved in sexual reproduction (such as skin cells, blood cells, or muscle cells). By creating two identical daughter cells from one parent cell, mitosis allows the body to grow, repair damaged tissue, and replace old or dead cells.

Before mitosis begins, the cell replicates its DNA during a phase called interphase. Interphase is technically not part of mitosis, but it sets the stage for it. Once mitosis starts, it consists of five main phases: prophase, metaphase, anaphase, telophase, and cytokinesis.

The Stages of Mitosis

1. Prophase

Prophase is the first stage of mitosis. During this phase:

• The chromatin (a loose, thread-like form of DNA) condenses into visible chromosomes. Each chromosome is made up of two identical sister chromatids, joined at a central point called the centromere.
• The nuclear membrane (the protective envelope surrounding the nucleus) starts to break down.
• Structures called centrioles move to opposite ends, or poles, of the cell. These centrioles help organise the spindle fibres, which are essential for separating the chromosomes later.
• Spindle fibres begin to form from the centrioles. These fibres act like ropes, ensuring the chromosomes are correctly divided between the two new cells.

Prophase sets the stage for the chromosomes to align and separate in the following phases.

2. Metaphase

In metaphase, the chromosomes line up in the middle of the cell, along an imaginary line called the “metaphase plate.”

• Each chromosome is attached to spindle fibres via the centromere.
• The alignment ensures that each new cell will receive one chromatid from each chromosome, ensuring genetic consistency.

This stage is a critical checkpoint. If the chromosomes are not properly aligned, the cell may stop the process to prevent mistakes in division.

3. Anaphase

Anaphase is the stage where the sister chromatids are pulled apart to opposite ends of the cell.

• The spindle fibres shorten, pulling the chromatids away from each other.
• Once separated, the chromatids are now referred to as “daughter chromosomes.”
• Equal distribution of the chromosomes ensures that each new cell will have the exact same set of genetic material as the original parent cell.

Anaphase is a rapid stage, but it is essential for maintaining genetic balance in the new cells.

4. Telophase

During telophase, the cell begins to finalise the division of its contents.

• The chromosomes arrive at opposite poles of the cell and begin to uncoil, returning to their thread-like chromatin form.
• A new nuclear membrane forms around each set of chromosomes, creating two separate nuclei.
• The spindle fibres break down as they are no longer needed.

Telophase marks the end of nuclear division, but the entire cell has yet to split completely. That happens in the next phase, cytokinesis.

5. Cytokinesis

Cytokinesis is the final step in cell division.

• The cell’s cytoplasm (the jelly-like material surrounding the organelles) is divided into two.
• A structure called the cleavage furrow forms in animal cells, pinching the cell in half to create two separate daughter cells.
• In plant cells, a cell plate forms instead, which eventually turns into a new cell wall separating the two new cells.

By the end of cytokinesis, the original parent cell has been divided into two identical daughter cells. Each of these cells contains an identical copy of the DNA and is ready to carry out its functions.

Why is Mitosis Important?

Mitosis isn’t just a biological process; it’s a lifeline for multicellular organisms. Here’s why it matters:

• Growth: Mitosis allows organisms to grow by increasing the number of cells. For instance, it’s how a fertilised egg (a single cell) develops into a multicellular organism.
• Repair: Mitosis replaces damaged or dead cells. For example, if you cut your skin, mitosis creates new skin cells to heal the wound.
• Maintenance: Cells naturally age and die. Mitosis replenishes these cells, ensuring tissues and organs continue functioning.

Errors in Mitosis

Though mitosis is highly regulated, errors can happen. These errors are often caused by problems with the spindle fibres or checkpoints, leading to unequal chromosome distribution.

Such errors can result in:

• Aneuploidy: A condition where cells have extra or missing chromosomes. This can lead to genetic disorders, such as Down syndrome.
• Uncontrolled Cell Division: Errors in cell division control can lead to tumours and, potentially, cancer.

These issues highlight the need for careful regulation of the mitosis process to prevent health problems.

Mitosis vs. Meiosis

Mitosis differs from meiosis, even though both are forms of cell division.

• Mitosis creates two genetically identical daughter cells used for growth and repair.
• Meiosis, on the other hand, produces four genetically unique daughter cells, each with half the number of chromosomes. Meiosis occurs in reproductive cells to form eggs and sperm.

Both processes are essential for the survival of living organisms but serve very different purposes.

Summary

Here is a summary of mitosis for reference:

• Mitosis creates two identical daughter cells from one parent cell.
• It occurs in somatic cells for growth, repair, and maintenance.
• The process has five key stages: prophase, metaphase, anaphase, telophase, and cytokinesis.
• DNA is replicated before mitosis begins, ensuring each daughter cell has an identical copy.
• Regulation of mitosis is critical to prevent health issues from arising.

Mitosis in Health and Social Care

In health and social care, understanding mitosis is essential. It helps professionals provide better care and advice for various conditions, including cancer and genetic disorders. For example:

• When treating patients with cancer, health care workers need to understand how uncontrolled mitosis contributes to tumour growth.
• In screening programmes, such as those for cervical or breast cancer, knowledge of cell division helps identify abnormal cell patterns.
• When explaining conditions to patients or families, understanding mitosis helps clarify how treatments like chemotherapy target dividing cells.

Professionals in health and social care use this knowledge daily to improve outcomes for individuals and the wider community.