2.4.12 Specialised Cells

Examples of Specialised Cells and Their Adaptations:

1. Red Blood Cells (Erythrocytes):

• Function: Transport oxygen around the body.
• Adaptations:
• Biconcave shape increases surface area for gas exchange.
• No nucleus or organelles, maximising space for haemoglobin.
• Thin membrane for easy diffusion of oxygen and carbon dioxide.

2. Root Hair Cells:

• Function: Absorb water and minerals from the soil.
• Adaptations:
• Long, thin extensions increase surface area for absorption.
• Thin cell wall reduces diffusion distance.
• Contain many mitochondria to provide ATP for active transport of mineral ions.

3. Epithelial Cells of the Small Intestine:

• Function: Absorb nutrients such as glucose and amino acids.
• Adaptations:
• Microvilli increase surface area for absorption.
• Rich supply of carrier and channel proteins for facilitated diffusion and active transport.
• Contain numerous mitochondria to supply energy for co-transport.

4. Sperm Cells:

• Function: Fertilise the egg cell (ovum).
• Adaptations:
• Flagellum enables mobility to swim towards the egg.
• Many mitochondria provide ATP for movement.
• Acrosome contains enzymes to penetrate the egg's outer layer.

5. Neurons (Nerve Cells):

• Function: Transmit electrical signals around the body.
• Adaptations:
• Long axons for transmitting signals over long distances.
• Myelin sheath insulates the axon, speeding up nerve impulse transmission.
• Numerous dendrites provide large surface area for connections with other neurons.

General Features of Specialised Cells:

1. Specific Proteins:

• Specialised cells produce proteins specific to their function (e.g., haemoglobin in red blood cells, digestive enzymes in gut cells).

2. Efficient Transport:

• Cells often contain transport proteins in their membranes to facilitate the movement of ions, nutrients, or gases.

3. Energy Supply:

• Cells that require active processes (e.g., root hair cells, epithelial cells) contain many mitochondria for ATP production.

4. Structural Adaptations:

• Features like microvilli, flagella, or biconcave shapes maximise efficiency in their specific roles.

Importance of Specialisation:

• Specialisation allows multicellular organisms to perform complex functions efficiently by dividing tasks among different cell types.
• These cells work together in tissues, organs, and organ systems to maintain homeostasis and ensure survival.