Cambridge IGCSE Biology: Topic 2.1 Cell Structure

Key Concepts

• Terms to Describe:
  • Cell: Basic unit of life.
  • Tissue: Group of similar cells performing a shared function.
  • Organ: Structure made of tissues, working together for a specific function.
  • Organ System: Group of organs with related functions.
  • Organism: A complete living thing, capable of independent life.

Cell Structures

Animal and Plant Cells

• Cytoplasm

  • Jelly-like substance with nutrients and organelles.
  • Site of chemical reactions, enclosed by cell membrane.

• Cell Membrane

  • Partially permeable; controls movement of substances in and out of the cell.

• Nucleus

  • Contains DNA in chromosomes, controls cell activities.

• Mitochondria

  • Oval-shaped, release energy via aerobic respiration.

• Ribosomes

  • Sites of protein synthesis; found free or attached to membranes.

Plant Cells Specific

• Cell Wall

  • Made of cellulose, offers support and allows passage of water/salts.

• Chloroplasts

  • Contain chlorophyll for photosynthesis.

• Vacuole

  • Fluid-filled, contains cell sap, maintains cell structure.

Bacterial Cells

• Structure
  • Include cytoplasm, cell membrane, ribosomes, and a non-cellulose cell wall.
  • Lacks a nucleus; has a single chromosome and plasmids for genetic information.

Cell Production

• Mitosis
  • Process of cell division, controlled by the nucleus.
  • Chromosomes replicate, nucleus divides to form new cells.

Specialized Cells

Animal Cells

• Ciliated Cells: Line respiratory system, covered with cilia for mucus movement.

• Neurons: Transmit information via electrical impulses.

• Red Blood Cells

  • Transport oxygen, contain hemoglobin, have biconcave shape.

• Sperm Cells

  • Comprised of head, midsection, and tail; specialized for reproduction.

• Egg Cells

  • Contain nucleus, cell membrane, jelly coat; nutrition from yolk droplets.

Plant Cells

• Root Hair Cells

  • Absorb water/minerals; have large surface area.

• Palisade Mesophyll Cells

  • Packed with chloroplasts, site of photosynthesis.

Conclusion

• Summary: Full coverage of cell structure, types, and functions in living organisms.
• Next Topic Preview: Topic 2.2 Size of Specimens.