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Prokaryotic Life
Characteristics
Reproduction
Evolution
Structure
A bacterium such as E. coli has the basic structure typical of
most prokaryotes: cell wall, cell membrane, and cytoplasm. Some
prokaryotes have flagella that they use for movement. The pili
are involved in cell-to-cell contact. The cell walls of eubacteria
contain peptidoglycan.
Characteristics
Small
– Few micrometers in
length
Unicellular
No nucleus
No membrane bound
organelles
May have flagella for
movement
Characteristics
Energy- How do bacteria acquire energy?
Prokaryotes can be autotrophs or heterotrophs
-Autotrophs:
-Self producers, by sunlight or organic chemicals
-Chemoautotrophs
-Photoautotrophs
-Heterotrophs:
- Consumes energy from other organisms
Bacterial Reproduction
Binary Fission
- Parent cell splits into
two identical daughter
cells
Conjugation
- Sharing genetic
information
- Results in genetic
variation
Binary Fission Video
Video
Did you know? Fun Facts
• There are 10 times more bacterial cells living on and in you,
than your own body cells.
• You have more bacterial DNA than human DNA on you.
• All the bacteria living in/on you weighs about the same as a
human brain.
Binary Fission-Asexual Reproduction
What must happen first before the cell can divide?
-Conjugation (sexual) : swapping genes over a
bridge between two bacteria
Think:
Which of these two types of
reproduction is more
beneficial and why?
Do they both have
advantages?
Think Question
Cell Enlargement Vs. Cell Division
What’s the Difference?
Prokaryotic Cell
Cycle
G1- Gap 1 Phase
Growth
S- Synthesis of DNA
(DNA Replication)
G2- Gap 2 Phase
The bacterial cell
prepares to divide
Evolution
Prokaryote success depends on various selective pressures
Like other organisms, if prokaryotes can survive their environment
they will then survive and reproduce
Obstacles that bacteria have to overcome:
– Temperature
– Food
– Chemical balance
– Antibiotics
– Antimicrobials
Evolutionary Success
Rapid reproduction time
– Successfully passing on
genetic information from
parents to offspring
Diversity
- FOUND EVERYWHERE
- Air, soil, water, on plants,
animals, and humans!
Examples of Bacterial Evolution:
Bacterial resistance to
antibiotics
-
As bacteria evolves, medicine also
needs to evolve in order to
effectively treat the bacterial
infections
-
Mrsa
– Methicillin-resistant Staphylococcus
aureus (MRSA) infection is caused
by a strain of staph bacteria that's
become resistant to the antibiotics
commonly used to treat ordinary
staph infections.
– Most MRSA infections occur in
people who've been in hospitals or
other health care settings, such as
nursing homes and dialysis centers
Example of Bacteria Evolution
Resistance to antimicrobials (hand
sanitizer)
- Formulas constantly change to
keep up with bacteria evolution
- Knocks out the weak bacteria
- Strong bacteria survive, and
these go on to reproduce
Evolution of antibiotic resistant bacteria
Bacteria can share genetic content. This is why bacteria are
so successful: the sharing of advantageous traits may enable
evolving species to become even more successful.
Successful Evolution
• Bacteria can reproduce very rapidly!
– E. coli can reproduce in just 20 minutes!
• Environments exert natural selection on
populations causing them to change.
Evolution of Prokaryotes
• http://ed.ted.com/lessons/how-antibioticsbecome-resistant-over-time-kevin-wu
Evolution of Prokaryotes
• http://ed.ted.com/lessons/how-antibioticsbecome-resistant-over-time-kevin-wu