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Understanding Cell Structures and Functions

May 20, 2025

Organisation of the Organism - CIE Biology IGCSE

Overview

  • Eukaryotic cells: Plant and animal cells with a nucleus and membrane-bound organelles.
  • Prokaryotic cells: Bacteria without a nucleus or membrane-bound organelles.
  • Microscopy: Used to view cells and calculate specimen sizes.

Functions of Eukaryotic Cell Structures

  • Cytoplasm: Jelly-like material where reactions occur, contains ribosomes and vesicles.
  • Cell Membrane: Controls entry and exit of substances.
  • Nucleus & DNA: Contains genetic material, site of DNA replication.
  • Ribosomes & RER: Site of protein synthesis.
  • Mitochondria: Site of respiration, energy production.
  • Vesicles: Transport materials within the cell.

Additional Structures in Plant Cells

  • Vacuole: Fluid-filled sac with minerals, sugars, and pigments.
  • Chloroplasts: Site of photosynthesis, converts light energy to glucose.
  • Cell Wall: Provides structure, prevents bursting, controls permeability.

Levels of Organisation

  • Tissue: Group of similar cells for a specific process.
  • Organ: Group of tissues for a specific function.
  • Organ System: Group of organs for body functions.

Specialised Cells

  • Ciliated Cells: Line the trachea with cilia to move mucus and bacteria.
  • Root Hair Cells: Large surface area for osmosis and mineral uptake.
  • Xylem Vessels: Transport water, hollowed-out cells for capillary action.
  • Palisade Mesophyll Cells: Photosynthesis, packed with chloroplasts, located at top of leaf.
  • Nerve Cells: Transmit electrical impulses, myelinated, contain mitochondria, branched dendrites.
  • Red Blood Cells: Carry oxygen, biconcave shape for diffusion, no nucleus.
  • Sperm Cells: Contain mitochondria, tail for movement, enzymes for egg penetration.