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1.1.2Unit 1 — Cell Biology

Fungal and Bacterial Cells — SQA National 5 Biology Revision Notes & Topical Questions

5 min read 4 parts Lesson 3 of 28

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Part 1 of 4Fungal Cells

1.1.2 Fungal and Bacterial Cells

Fungi are usually multicellular, but some such as yeast are single-celled.

Fungal Cells
Shared features
  • Fungal cells have a nucleus, cell membrane, cytoplasm, mitochondria and ribosomes, like animal and plant cells.
Cell wall
  • They have a cell wall made of chitin, which has a different structure from the cellulose wall of a plant cell.
No chloroplasts
  • Fungal cells have no chloroplasts, so they cannot carry out photosynthesis.
Example
  • Yeast is a common example of a fungus that exists as a single cell.

Part 2 of 4Bacterial Cells

Bacterial cells vary widely in shape and size and are simpler in structure than other cells.

Cell wall
  • A wall that differs in structure from the cell wall of plants, giving the cell protection and shape.
Membrane and cytoplasm
  • A cell membrane controls what passes in and out, and the cytoplasm is where reactions take place.
Ribosomes
  • Bacteria have ribosomes where proteins are made.
Circular chromosome
  • The genetic material is a single circular DNA molecule lying free in the cytoplasm.
Plasmids
  • Small extra rings of DNA that are separate from the main chromosome.

Part 3 of 4Key Differences

Bacterial cells lack internal membrane-bound structures.

1
Bacterial cells do not contain a nucleus, because their DNA is not enclosed in a membrane.
2
They do not contain mitochondria or any other organelle surrounded by a membrane.
3
Fungal cells do contain a nucleus and mitochondria, which makes them more like animal and plant cells.
4
Neither fungal nor bacterial cells have the chloroplasts of plant cells.

Part 4 of 4Exam Checklist & Tips

1.1.2 – Key Points for the Exam

  • Chitin The material that forms the cell walls of fungi.
  • Plasmid A small ring of DNA in a bacterial cell, separate from the main chromosome.
  • Yeast A single-celled fungus.
  • Circular chromosome The single loop of DNA that makes up the genetic material of a bacterium.

Common Mistakes

  • Stating that bacteria have a nucleus; their DNA lies free in the cytoplasm.
  • Saying that fungal cell walls are made of cellulose, when they are made of chitin.
  • Forgetting plasmids when listing bacterial cell structures.
  • Assuming all fungi are multicellular, when yeast is a single-celled fungus.

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Cambridge 9700 AS Biology Core Formula

Magnification Triangle & Unit Conversion

Formula: M = I / A  ⇔  A = I / M  ⇔  I = M × A

Units: 1 mm = 1,000 μm = 1,000,000 nm.
Rule: Convert Image size (ruler mm) to μm by ×1,000 before dividing by Actual size.