Cell Structure and Types Cells are the fundamental units of life, divided into two main types: Prokaryotic cells (e.g., bacteria) lack a true nucleus and membra...
Cell Structure and Types
Cells are the fundamental units of life, divided into two main types:
Prokaryotic cells (e.g., bacteria) lack a true nucleus and membrane-bound organelles.
Eukaryotic cells (plant and animal cells) have a nucleus and various organelles, each with specific functions.
Key Organelles and Their Functions
Nucleus: Contains genetic material (DNA) and controls cellular activities.
Cytoplasm: Jelly-like substance where chemical reactions occur.
Cell membrane: Selectively permeable barrier controlling movement in and out of the cell.
Mitochondria: Produce energy (ATP) through cellular respiration.
Ribosomes: Site of protein synthesis.
Cell wall (plants only): Provides structural support and protection.
Chloroplasts (plants only): Site of photosynthesis, converting light energy into chemical energy.
Vacuole: Storage compartment for nutrients, waste, and water.
Cell Division and Specialisation
Cells undergo division to grow, repair, and reproduce. Mitosis is the process of cell division in somatic (body) cells, involving the duplication and separation of genetic material.
Calculating Magnification
To determine the size of cells or structures observed under a microscope, magnification calculations are used:
Magnification = Size of Image / Size of Actual Object
Stem cells are unspecialised cells capable of dividing and differentiating into specialised cell types (e.g., muscle, nerve, blood cells) through cell specialisation.
Organism Organisation
Multicellular organisms are hierarchically organised, from cells to tissues, organs, and organ systems:
Cells → Tissues → Organs → Organ Systems
Human Body Systems
Digestive System: Breaks down food into smaller molecules for absorption and energy.
Respiratory System: Facilitates gas exchange (oxygen and carbon dioxide) through breathing.
Circulatory System: Transports oxygen, nutrients, and waste through the body via the heart and blood vessels.
Plant Organisation
Plants have specialised tissues for transport and support:
Xylem: Transports water and minerals from roots to leaves.
Phloem: Distributes products of photosynthesis (e.g., sucrose) around the plant.
Transpiration and translocation are processes that facilitate the movement of water and nutrients in plants.