Asexual reproduction

1
Bacteria Growth and Reproduction

• Asexual reproduction
• Sexual reproduction

2
What do bacteria need to grow?

• Energy
• Nutrients
• Water
• Appropriate temperature
• Appropriate pH
• Presence of absence of oxygen

3
Reproduction

• ASEXUAL REPRODUCTION BINARY FISSION

• Bacteria reproduce by splitting into two new
  bacterial cells
• This process is called Binary Fission
• Results in 2 identical daughter cells with one
  copy of parental DNA

4
Binary Fission

• Steps

• 1) Bacterial DNA duplicates
• 2) Bacterial Cell elongates
• 3) Cell membrane/wall form cross wall
• 4) Daughter cells separate

5
Binary Fission

• Results

• 2 identical daughter cells
• Same genetic makeup as parents
• Not much diversity unless there is a MUTATION

6
Bacteria Growth Phases

• Under ideal conditions bacteria would grow
  exponentially
• Ex labs
• Ideal conditions are rarely met therefore the
  growth curve look different

7
Bacterial Growth

• Lag phase bacteria getting ready to reproduce,
  accumulating food
• Log phase period of rapid reproduction
• Stationary phase rate of reproduction rate of
  death
• Bacteria competing with each other
• Death phase toxic waste build up, food depleted,
  rate of death gt rate of reproduction

8
Generation Time

• Bacteria can divide about every 15-20 minutes
  under ideal conditions
• Generation time
• Time required for one cell to produce 2 new cells
• Time taken for one cell division

9
Generation Time

• How can we calculate how many bacteria are
  present after a certain amount of cell division?

• Formula Bb x 2n

• B of bacterial cells present
• b original of bacterial cells
• n of cell divisions

10
Sexual reproduction

• If Binary Fission results in identical cells then
  how do we can the diverse amount of bacteria
  present?

• Bacterial cells do not have sex however do have
  a modified form of sexual reproduction
• 3 ways of how bacteria can get genetic diversity
• CONJUGATION
• TRANSFORMATION
• TRANSDUCTION

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CONJUGATION

• STEPS

• 1) 2 bacterial cells attach via Pilli
• 2) conjugation bridge forms
• 3) Donor cell sends part of its DNA to recipient
  cell
• 4) now cells can divide via Binary Fission and
  have genetic diversity.

12
Transformation

• Bacterial cells pick up DNA from dead or dying
  bacterial cells
• Can get incorporated into chromosomal DNA or stay
  as a plasmid

13
Transduction

• Use viruses to transfer DNA from one bacteria to
  another
• Viruses that infect bacteria and called
  bacteriophages