A LevelBiologyAQARevision NotesCell StructureCell Division in Eukaryotic & Prokaryotic CellsBinary Fission

Binary Fission (AQA A Level Biology): Revision Note

Exam code: 7402

Lára Marie McIvor

Written by: Lára Marie McIvor

Reviewed by: Ruth Brindle

Updated on

Binary fission of prokaryotic cells

  • Cell division in prokaryotes is called binary fission

  • It is simpler than mitosis as cells have no nucleus, chromosomes, spindle fibres, or membrane-bound organelles

  • Prokaryotes only need to replicate

    • a single, circular DNA molecule

    • plasmids: small, circular DNA molecules

The process of binary fission

  1. The circular DNA molecule is replicated

  2. Plasmids replicate

  3. The cytoplasm divides (roughly) equally between daughter cells

  4. Each daughter cell is genetically identical and receives

    • one copy of circular DNA

    • a variable number of plasmids

  • There are mechanisms to ensure that all daughter cells inherit a copy of the single, circular DNA molecule along with some plasmids

    • If a daughter cell does not receive the single circular DNA molecule or at least one copy of a plasmid, it dies

Diagram illustrating bacterial binary fission: a cell with circular DNA and plasmid doubles contents, divides into two genetically identical cells.
Binary fission produces two genetically identical daughter cells

Examiner Tips and Tricks

Binary fission can be a rapid process. Bacteria can divide every 20 minutes under ideal conditions. This rapid reproduction allows them to:

  • Colonise new environments quickly

  • Outcompete other microbes

  • Accumulate mutations faster, increasing genetic variation (contributing to the issues surrounding antibiotic resistance)

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    Author
    Reviewer
    Lára Marie McIvor

    Author: Lára Marie McIvor

    Expertise: Biology, Psychology & Sociology Subject Lead

    Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.

    Ruth Brindle

    Reviewer: Ruth Brindle

    Expertise: Biology Content Creator

    Ruth graduated from Sheffield University with a degree in Biology and went on to teach Science in London whilst also completing an MA in innovation in Education. With 10 years of teaching experience across the 3 key science disciplines, Ruth decided to set up a tutoring business to support students in her local area. Ruth has worked with several exam boards and loves to use her experience to produce educational materials which make the mark schemes accessible to all students.