1.3.1

Introduction to Cells

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Eukaryotic vs Prokaryotic Cells

All life on Earth exists as cells. A cell is the smallest unit of a living thing. All cells can be grouped into either eukaryotic or prokaryotic cells. These different categories have similarities and differences.

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Similarities

  • Both prokaryotic and eukaryotic cells contain organelles.
  • The cell-surface membrane in eukaryotic and prokaryotic cells is made of a phospholipid bilayer.
    • This bilayer is responsible for controlling the passage of substances across exchange surfaces.
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Differences

  • Prokaryotic cells make up single-celled prokaryotic organisms (e.g. bacteria). In contrast, eukaryotic cells make up complex eukaryotic organisms (e.g. animals, plants, fungi and algae).
  • Eukaryotic cells are larger and more complex than prokaryotic cells.
  • Cells arise from other cells by binary fission in prokaryotic cells and by mitosis or meiosis in eukaryotic cells.

Types of Eukaryotic Cells

Eukaryotic cells have similar structures across different types of organisms. But there are some key differences that are outlined here.

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Animal cell

  • Most animal cells have the following organelles:
    • Mitochondria.
    • Ribosomes.
    • Endoplasmic reticulum (ER).
    • Golgi.
    • Lysosomes.
    • Nucleus.
  • Animal cells are enclosed by a cell membrane.
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Plant cell

  • Plant cells contain all the organelles found in animal cells.
  • Plant cells also possess:
    • Vacuole (a repository of cell sap).
    • Chloroplasts (the site of photosynthesis).
    • Cell wall (made of cellulose and contains plasmodesmata, through which cells exchange substances with each other).
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Algal cells

  • Algal cells and plant cells have an identical set of organelles.
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Fungal cells

  • Fungal cells are similar to plant cells, apart from:
    • There are no chloroplasts in fungal cells.
    • The cell walls of fungal cells are made from chitin instead of cellulose.

Jump to other topics

1Principles of Science I

1.1Structure & Bonding

1.2Properties of Substances

1.3Cell Structure & Function

1.4Cell Specialisation

1.5Tissue Structure & Function

1.6Working with Waves

1.7Waves in Communication

2Practical Scientific Procedures and Techniques

3Science Investigation Skills

4Principles of Science II

4.1Extracting Elements

4.2Relating Properties to use of Substances

4.3Organic Chemistry

4.4Energy Changes in Industry

4.5The Circulatory System

4.6Ventilation & Gas Exchange

4.7Urinary System

4.8Cell Transport

4.9Thermal Physics

4.10Materials

4.11Fluids

5Contemporary Issues in Science

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