2.1.4 Eukaryotic Cell Organisation

Organisation in Multicellular Organisms:

1. Cells:

• Basic unit of life.
• Specialised to perform specific functions, such as nerve cells for transmitting signals or red blood cells for oxygen transport.

2. Tissues:

• Groups of similar cells working together to perform a particular function.
• Example: Muscle tissue contracts for movement, while epithelial tissue lines surfaces.

3. Organs:

• Structures made of several tissues that work together to perform complex functions.
• Example: The heart pumps blood using muscle tissue, nerve tissue, and connective tissue.

4. Organ Systems:

• Groups of organs that work together to carry out vital processes.
• Example: The digestive system includes organs like the stomach and intestines to break down and absorb food.

Specialisation in Eukaryotic Cells:

• Eukaryotic cells have specific organelles to support their function. For example:
  • Chloroplasts in plant cells enable photosynthesis.
  • Mitochondria in animal cells provide energy for processes like movement and active transport.
• Differentiation of cells occurs during development, where cells become specialised by expressing specific genes.

Hierarchy of Organisation:

• Cells → Tissues → Organs → Systems → Organism.