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Cambridge A Level Biology — Full F-drive source: 1 · Cell Structure — Cambridge AS & A Level Biology 9700 Revision Notes & Topical Questions

5 min read 7 parts Lesson 13 of 13 Unit quiz

📚 Cambridge AS & A Level Biology 9700 Hub / Topical Revision
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1 · Cell Structure — Prokaryotes, Viruses and ATP — CAMBRIDGE AS & A LEVEL BIOLOGY 9700 — REVISION NOTES notes: Compare prokaryotic and eukaryotic cells, describe viruses and explain the role of ATP.Prokaryotes — circular DNA free in the cytoplasm, no membrane-bound organelles an…

  • Eukaryotes
  • Attachment proteins
  • Immediate source
  • Common structures
  • Plant only
  • Animal only

Part 1 of 5Prokaryotes and eukaryotes

Prokaryotes
  • Prokaryotes circular DNA free in the cytoplasm, no membrane-bound organelles and 70S ribosomes.
  • Cells are 0.5–5 µm and always unicellular.
  • The cell wall is made of peptidoglycan.
Eukaryotes
  • Eukaryotes linear chromosomes with histones in a nucleus, membrane-bound organelles and 80S ribosomes.
  • Cells are up to 100 µm and can form multicellular organisms.
  • Walls are cellulose in plants and chitin in fungi.
Division
  • Division prokaryotes divide by binary fission with no spindle, and eukaryotes by mitosis or meiosis with spindle fibres.

Part 2 of 5Viruses

Viruses
Not cells
  • Not cells non-cellular particles of 20–300 nm that only reproduce inside host cells.
Structure
  • Structure a DNA or RNA core inside a protein capsid, sometimes with an envelope from the host membrane.
Attachment proteins
  • Attachment proteins bind to host cell receptors so the virus can infect.

Part 3 of 5ATP and energy

Need
  • Need cells need energy for anabolic reactions, active transport, muscle contraction and nerve impulses.
ATP
  • ATP a nucleotide hydrolysed to ADP and inorganic phosphate to release energy, and regenerated in respiration.
Immediate source
  • ATP, not glucose, directly provides energy for cell processes.

Part 4 of 5Plant and animal cells compared

Plant and animal cells compared
Common structures
  • Common structures membrane, cytoplasm, nucleus, mitochondria, ER, Golgi, ribosomes, vesicles and lysosomes.
Plant only
  • Plant only cellulose wall, large vacuole, chloroplasts and plasmodesmata.
Animal only
  • Animal only centrioles and microvilli.

Part 5 of 5More from the specification

1Endoplasmic Reticulum in Protein and Lipid Synthesis
  • The endoplasmic reticulum is a network of membrane-bound flattened sacs called cisternae;
    • rough endoplasmic reticulum is studded with ribosomes for synthesizing exported proteins,
  • while smooth endoplasmic reticulum synthesizes lipids and steroids.
2Microtubules and the Cytoskeletal Network
  • Microtubules are hollow cylindrical polymers composed of tubulin dimers that form part of the cytoskeleton, providing structural support, enabling intracellular transport of substances,
  • and forming the spindle apparatus during mitosis.
3Cell Surface Adaptations and Microvilli
  • In specialized epithelial cells,
  • such as those lining the small intestine and kidney tubules, the cell surface membrane forms microscopic finger-like projections called microvilli to greatly expand surface area for absorption of substances.
4Organelle Identification in Electron Micrographs
  • High-resolution electron micrographs reveal fine ultrastructural details of living cells, showing membrane-bound organelles surrounded by single or double lipid bilayers containing specialised enzymes.
5Electron micrograph
  • A photograph taken through an electron microscope.
6Aerobic respiration
  • Respiration that uses oxygen to release a relatively large amount of energy.
7Permanent vacuole
  • Sap-filled space that keeps a plant cell firm.
8Microtubule
  • Hollow protein filament used for support and transport.
9Micrograph
  • A photograph taken through a microscope.
10Endoplasmic reticulum
  • Rough and smooth (lipids, detoxification).
    • (ribosomes, proteins)

Key terms

TermMeaning
ProkaryoteA cell with no nucleus or membrane-bound organelles.
EukaryoteA cell with a nucleus and membrane-bound organelles.
Binary fissionDivision of a prokaryote into two daughter cells.
CapsidThe protein coat of a virus.
ATPAdenosine triphosphate, the energy currency of cells.
PeptidoglycanThe bacterial cell wall polymer.

Avoid these mistakes

1
Saying prokaryotes have no DNA — they have it free in the cytoplasm.
2
Calling viruses cells or living organisms — they are non-cellular particles.
3
Stating all cell walls are cellulose — bacteria use peptidoglycan and fungi chitin.
4
Saying ATP is a long-term energy store — it is a short-term carrier.

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