Plate 15 - Bacterial Reproduction
Sexual vs. Asexual Reproduction
Asexual – no change in genetic makeup of daughter cells, all are identicalSexual – daughter cells are genetically different than parents
Gametes
Gametes – sex cells (sperm & egg), the result of meiosis
Binary Fission
Binary = 2Fission = split apartAsexual reproduction Occurs after a period of growth
Binary Fission Steps1. 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 & structuresCauses increase in mass of cell & length
Effects of Antibiotics
Penicillin acts to weaken cell wallCell wall is so weak that cell bursts and dies (like using paper instead of concrete blocks for walls) Only works on growing cellsMature cells are NOT affected
Daughter Cells
“Daughter” is a misnomer, but still used (not female)
Generation TimeGenetically 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