Plate 15 - Bacterial Reproduction

Sexual vs. Asexual Reproduction

Asexual – no change in genetic makeup of daughter cells, all are identical

Sexual – daughter cells are genetically different than parents

Gametes

Gametes – sex cells (sperm & egg), the result of meiosis

Binary Fission

Binary = 2

Fission = split apart

Asexual reproduction

Occurs after a period of growth

Binary Fission Steps

1. DNA replication (time frame is minutes or hours)

2. Protein synthesis (~ 40 minutes)

3. Replication of structures (7 minutes)

4. Cytoplamic separation & pinching (7 minutes)

5. New cell walls form (7 minutes)

DNA

DNA is copied by cell enzymes (transcription)

Makes 2 copies (looped DNA)

Cytoplasm

Increase in metabolism causes rapid manufacture of cytoplasm & structures

Causes increase in mass of cell & length

Effects of Antibiotics

Penicillin acts to weaken cell wall

Cell wall is so weak that cell bursts and dies (like using paper instead of concrete blocks for walls)

Only works on growing cells

Mature cells are NOT affected

Daughter Cells

“Daughter” is a misnomer, but still used (not female)

Generation Time

Genetically determined, different species different times to undergo binary fission

Ex: E. coli = 20 minutes

Environment also determines the generation time (cold temperatures slow it down)

Measured from the start of one binary fission event to the start of the next