Pre-U Biology CAIE

Cell Structure

Cell Structure

- Cells: Basic units of life, structured into two main types: prokaryotic cells (simple, single-celled organisms) and eukaryotic cells (complex, multicellular organisms).

- Prokaryotic Cells:

• Lacks a nucleus and other membrane-bound organelles.
• Contains a circular strand of DNA floating freely within the cell.
• Examples include bacteria and archaea.

- Eukaryotic Cells

• Possess a nucleus and other membrane-bound organelles.
• DNA is contained within the nucleus.
• Examples include animal, plant, and fungal cells.

Key Parts of a Cell

- Cell Membrane:

• Protective barrier that controls the movement of substances in and out of the cell.
• Made up of a phospholipid bilayer with embedded proteins.

- Nucleus:

• Control centre of the cell, contains cell's DNA.
• Surrounded by a nuclear membrane.

- Mitochondria:

• Powerhouse of the cell, provides energy through the process of respiration.
• Contains its own DNA.

- Ribosomes:

• Sites of protein synthesis.
• Found in all types of cells.

- Endoplasmic Reticulum:

• Network of membranous sacs involved in production, processing, and transport of proteins and lipids.

- Golgi Apparatus:

• Packaging centre of the cell, modifies and packages proteins for transport.

- Lysosomes:

• Digestive compartments filled with enzymes to break down waste material and cellular debris.

- Vacuoles and Vesicles:

• Storage compartments.

- Cytoskeleton:

• Provides structure and shape to the cell, involved in cell movement.

Differences between Animal and Plant Cells

- Cell Wall:

• Found in plant cells, provides rigidity and structural support.
• Absent in animal cells.

- Chloroplasts:

• Found in plant cells, site of photosynthesis.
• Absent in animal cells.

- Centrioles:

• Found in animal cells, involved in cell division.
• Rarely present in plant cells.

- Large central vacuole:

• Found in plant cells, stores water and nutrients.
• Small, numerous vacuoles present in animal cells.

For a comprehensive understand of cell structure and cell processes, diagrams and visual aids are helpful in conjunction with these points. Remember that mastering the basics provides a firm foundation for complex topics.