National 5 Biology - Unit 1: Cell Biology

Key Area 1: Cell Structure

Types of Cells

• Animal Cells
  • Structures: Cell membrane, mitochondria, ribosomes, nucleus, cytoplasm
• Plant Cells
  • Structures: Cell membrane, mitochondria, ribosomes, nucleus, cytoplasm, chloroplasts (contains chlorophyll for photosynthesis), vacuole (contains cell sap), cell wall (supports and strengthens the cell)
• Bacterial Cells
  • Structures: Cell membrane, ribosomes, cytoplasm, plasmids (genetic material, rings), bacterial chromosomes, cell wall
• Fungal Cells
  • Similar to animal cells but with a cell wall
  • Structures: Cell wall, cell membrane, ribosomes, cytoplasm, nucleus, mitochondria
  • Note: Yeast cells are an example of fungal cells

Identifying and Comparing Cells

• Be able to identify cells based on their structures
• Recognize unique structures to differentiate cell types (e.g., chloroplasts and vacuoles for plant cells, plasmids for bacterial cells)

Functions of Cell Organelles

• Cell Wall
  • Present in plant, bacterial, and fungal cells
  • Supports and strengthens the cell
  • Freely permeable; made of cellulose
• Cell Membrane
  • Found in all cell types
  • Selectively permeable; controls the substances entering and leaving the cell
• Cytoplasm
  • Jelly-like substance in all cells
  • Site of chemical reactions
• Mitochondria
  • Found in animal, plant, and fungal cells (not in bacterial cells)
  • Site of aerobic respiration; produces ATP (energy)
• Chloroplasts
  • Found only in plant cells
  • Contains chlorophyll; site of photosynthesis
• Vacuole
  • Found in plant cells
  • Contains cell sap; supports the cell
• Ribosomes
  • Found in all cell types
  • Site of protein synthesis
• Plasmids
  • Found only in bacterial cells
  • Rings of genetic material
• Nucleus
  • Found in animal, plant, and fungal cells (not bacterial cells)
  • Controls cell activities and stores genetic information

Practice Problems

• Identify Plant Cells
  • Look for the presence of cell wall, cell membrane, and vacuole
• Structure Composition
  • Cell wall is made of cellulose
• Cell Features and Functions
  • Match structures like mitochondria with their functions (aerobic respiration)

Important Notes

• Review and familiarize yourself with diagrams of different cell types
• Use tables to compare cell structures and their functions
• Practice past paper questions to reinforce your understanding