1. Bacteria & Viruses
Chapter 19

3. Bacteria are Prokaryotes
Unicellular
Lack a nucleus & membrane bound organelles
Smaller than eukaryotic cells (1-5µm)

4. Classifying Prokaryotes
All bacteria were once placed in Kingdom Monera
Now divided into 2 separate Kingdoms
1)archaebacteria
2)eubacteria

5. Archaebacteria Origin 3.5 billion years ago Characteristics
Unusual lipids in their cell membrane
Introns in their DNA
Unique rRNA
No peptidoglycan in their cell wall
Unaffected by many antibiotics
Believed to be ancestors of eukaryotes
Most live in “harsh” environments

6. Categories of Archaebacteria
Methanogens
Use hydrogen gas for energy
Reduce carbon dioxide to methane
They live in swamps, mud, sewage, and animal guts.
Extremophiles
Thermophiles (60-80oC)
Halophiles – salinity of 15-30%
Acidophiles pH tolerant
Non-extremophiles
Same environment as eubacteria

7. Kingdom Eubacteria – smallest and most abundant living organism
Larger of the 2 Kingdoms
“Ubiquitous” (live almost everywhere)
Cell wall contains peptidoglycans
Lack introns in DNA

8. Identifying Prokaryotes
Identified by characteristics such as:
Shape
Chemical nature of cell wall
Type of movement
How they obtain energy (metabolism)

9. Bacterial shapes Basic Shapes Groupings Bacilli Cocci Spirilla
Straight rod
Cocci
spherical
Spirilla
Long and spiral
Groupings
Staph- grape cluster
Strep - chain

10. Cell walls 2 different types of cell walls are found in bacteria
Gram staining is used to tell them apart
Gram Positive Bacteria
Gram Negative Bacteria

11. Movement Some do not move Flagella Spiral snake-like
Glide on layer of slime

12. Metabolic Diversity
Bacteria are more diverse in terms of metabolism than any other kingdom
2 main groups:
1)heterotrophs (most)
2)autotrophs

13. Heterotrophs
Chemoheterotrophs: Must take in organic molecules for energy and supply of carbon.
Photoheterotrophs: photosynthetic but must take in organic molecules for carbon.

14. Autotrophs
Photoautotrophs: use light energy to convert CO2 and H2O into organic compounds. Cyanobacteria
Chemoautotrophs: use energy from chemical reactions to produce organic compounds from CO2. Bacteria near deep ocean vents.

15. Releasing Energy & O2
Bacteria either perform cellular respiration or fermentation to release energy from food.
Obligate aerobes: require oxygen
Obligate anaerobes: must live in absence of oxygen
Facultative anaerobes: can survive with or without oxygen

16. Growth and Reproduction
Bacteria can grow and divide quickly.
20 minutes
Bacteria only reproduce asexually by binary fission.
Produces clones

17. Conjugation Exchange of genetic information between bacteria.
Increases genetic diversity

18. Spore Formation
When conditions become unfavorable, many bacteria form a resistant, dormant structure called an endospore

19. Importance of bacteria
Decomposers: break down dead organisms and waste and recycle nutrients in ecosystems.
Nitrogen fixers: turn nitrogen gas into a form useable by plants in a process known as nitrogen fixation.
Used in industry to produce foods and beverages.
Make vitamins
Biotechnology uses