Cell division functions in reproduction, growth, and repair

The perpetuation of life is based on the reproduction of cells or cell division.
  • In unicellular organisms, the division of one cell to form two reproduces an entire organism (ex. Amoeba)
  • In multicellular organisms, cell division allows:
    • Growth and development from the fertilized egg.
    • Replacement of damaged or dead cells.
Cell Division is a complex process that faithfully passes along the genome from one generation of cells to the next. A dividing cell:
  • Precisely replicates its DNA
  • Equally distributes the DNA to opposite ends of the cell.
  • Separates into two identical daughter cells
Genome - Total endowment of DNA unique to each species.

Bacteria Reproduce by Binary Fission

Prokaryotes are smaller and simpler than eukaryotes. Prokaryotes:
  • Contain most genes in a single circular chromosome composed of a double-stranded DNA molecule and associated proteins
  • Contain only about 1/1000 the DNA of eukaryotes, but prokaryotic chromosomes still contain a large amount of DNA relative to the small prokaryotic cell. Consequently, bacterial chromosomes are highly folded and backed within the cell.

Prokaryotes reproduce by binary fission, a process during which bacteria replicate their chromosomes and equally distribute copies between the two daughter cells.
  • The chromosome is replicated; each copy remains attached to the plasma membrane at adjacent sites.
  • Between the attachment sites the membrane grows and separates the two copies of the chromosome.
  • The bacterium grows to about twice the initial size, and the plasma membrane pinches inward.
  • A cell wall forms across the bacterium between the two chromosomes dividing the original cell into two daughter cells.