Eukaryotes & Prokaryotes | AQA GCSE Biology Revision Notes & Diagram 2016

Introduction

• This lecture covers the basics of eukaryotic and prokaryotic cells, essential for AQA GCSE Biology.
• All cells share common features, essential components for their structure and function.

Cellular Components

• Key Components: All cells have essential components including the cell membrane, cytoplasm, and ribosomes.

Eukaryotic Cells

• Examples: Plant and animal cells.
• Characteristics:
  • Genetic material enclosed within a nucleus.
  • Contain cell membranes, cytoplasm, ribosomes, and other organelles.
  • Size ranges from 10 to 100 micrometers (µm).

Prokaryotic Cells

• Examples: Bacteria.
• Characteristics:
  • Genetic material not enclosed in a nucleus; found as a single DNA loop in the cytoplasm.
  • May contain plasmids - small, circular DNA.
  • Cell membranes surrounded by a cell wall made of peptidoglycan.
  • Much smaller than eukaryotic cells, about 1 µm in size.

Scale & Size of Cells

• Measurement: Cells measured in micrometers (µm), where 1 µm = 0.001 mm, or 1 x 10^-3 mm.
• Understanding Scale:
  • Important to convert between units, particularly between mm and µm.
  • Eukaryotic cells have subcellular structures as large as or larger than prokaryotic cells.
  • Differences in size expressed as order of magnitude (factor of 10).

Standard Form in Biology

• Usage: For representing very small or large numbers, e.g., cell sizes.
• Example: 1.5 µm can be expressed as 1.5 x 10^-3 mm.

Examiner Tips

• Be familiar with calculating and converting sizes of subcellular structures.
• Understand why certain structures, like mitochondria, may not be present in bacterial cells.

Conclusion

• Understanding the differences between eukaryotic and prokaryotic cells is crucial for GCSE Biology.
• Mastering cell size measurement and standard form is essential for exam success.

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