prokaryote notes

1. Ch. 19 - Bacteria and Viruses
Chapter 19

2. 19-1 Bacteria
• Common name for all prokaryotes
• unicellular organisms without a nucleus
• Were all in Monera
• Eubacteria
• live nearly everywhere
• normally protected by cell wall containing
peptidoglycan - cell membrane inside of cell wall

3. • Archaebacteria
• lack peptidoglycan
• DNA similar to eukaryotic DNA
• most are extremophiles – live in harsh
environments
• methanogens; halophiles; extreme thermophiles

4. Prokaryotic Body Plan
pilus
DNA
bacterial flagellum
capsule
plasma
membrane
cell wall
ribosomes
in cytoplasm
cytoplasm

5. Identifying Prokaryotes
1. Shape
a. bacilli(us) – rod-shaped
b. cocci(us) – spherical
c. spirilla(us) – spiral and
corkscrew shaped
2. Cell Walls
a. Gram-positive – have thick
peptidoglycan cell
walls that take and hold
stain
b. Gram-negative – thinner
cell walls with lipids
on outside – does not hold
stain
Gram Positive
Gram Negative
3. Movement

7. Metabolic Diversity
1. Chemoheterotrophs – must
take in organic
molecules for energy and a
supply of carbon
2. Photoheterotrophs – use
photosynthesis for
energy, but take in organic
compounds for
carbon source
3. Photoautotrophs – use
photosynthesis for both
energy and carbon source
4. Chemoautotrophs – use
chemosynthesis – get
energy from chemical
reactions and use carbon
dioxide as carbon source

8. Releasing Energy
- bacteria release energy by cellular respiration
and fermentation
A.Obligate Aerobes
- require a constant supply of oxygen
B. Obligate Anaerobes
- must live in the absence of oxygen
C. Facultative Anaerobes
- can survive with or without oxygen

9. Growth and Reproduction
- under good conditions
bacteria can reproduce
every 20 minutes
Binary Fission
- normal asexual
reproduction of bacteria
- replicate DNA and then
divide
Conjugation
- exchange of genetic
material between
bacterial cells
- increases genetic
diversity
Spore Formation
- allows survival of bad
conditions for a long
time

10. Prokaryotic Fission - 1
bacterial
chromosome
Bacterium before
DNA replication
DNA replication
begins
Figure 21.7
Page 350

11. Prokaryotic Fission - 2
parent DNA
molecule
DNA replication
completed
DNA copy
Membrane growth
moves DNA molecules
apart

12. Prokaryotic Fission - 3
New membrane and cellwall material deposited
Cytoplasm divided
in two

13. nicked plasmid
in donor cell
Conjugation
Transfer of plasmid
conjugation tube
to recipient cell

14. Importance of Bacteria
- while we usually think of bacteria negatively they are actually
essential to correct functioning in ecosystems
A. Decomposers
- primary decomposers who make nutrients available to plants
- used in sewage treatment plants also
B. Nitrogen Fixers
- Rhizobium in nodules of legume roots fix nitrogen in a form the
plants can use

15. C. Human Uses
• in food production
• in industry – can clean-up oil spills
• to synthesize drugs and chemicals
• genetic engineering now has them producing
human hormones
• Mutualism with Eschecaria coli in our colon
where they help us make vitamins