2. 19.1 Bacteria
Come in many shapes and sizes
Most common microorganisms are
prokaryotes
Average size of 1-5 micrometers
Compared to eukaryotic cells that are 10-
100 micrometers in diameter
3. Classifying Prokaryotes
Eubacteria
Largest prokaryote Domain
Cell wall of a carbohydrate- Peptidoglycan
Cell membrane around cytoplasm
Some have an extra cell wall on the
outside to resist damage
9. Metabolic Diversity
Autotrophs
Chemoautotrophs: perform
chemosynthesis to make carbon from
carbon dioxide. Does not require sunlight
Photoautotrophs: use light to convert
carbon dioxide and water into carbon
compounds and oxygen gas.
10. Getting Energy
Bacteria need a constant supply of energy
Obligate aerobes- require constant supply of
oxygen
Obligate anaerobes- need no oxygen, for some
oxygen will kill it
Facultative anaerobes- survive with or with out
oxygen
12. Importance of Bacteria
Decomposers
Break down dead matter
Nitrogen Fixers
Converts nitrogen into a form plants can
use
Humans use Bacteria
13. 19.2 Viruses
What is a virus?
Particles of nucleic acid and proteins
Core made up of DNA or RNA surrounded
by a capsid
Head
DNA
Need to infect a Tail
Tail fiber
living host to reproduce
14. Video on Lytic and Lysogenic
Cycle
http://www.youtube.com/watch?v=gU8X
eqI7yts&feature=related
15. Viral Infection
Lytic Cycle
Virus attaches to host cell
Injects its DNA
Host makes RNA from viral DNA
Cell begins to make copies of virus
New viruses form
Host cell bursts
16. Viral Infection
Lysogenic Cycle
Virus attaches to host cell
Injects DNA
Viral DNA incorporates itself into the host
DNA
Viral DNA can be dormant
Once it becomes active, it follows the 4
processes in the lytic cycle
17. Phage
Phage reproductive cycles Attaches 1
to cell
Phage DNA Bacterial
chromosome
Cell lyses,
releasing phages
Phage injects DNA
7
2 Many cell
4 divisions
Lytic cycle Lysogenic cycle
Phages assemble Phage DNA Lysogenic bacterium reproduces
Prophage
circularizes normally, replicating the prophage
at each cell division
3 5 6
OR
New phage DNA and Phage DNA inserts into the bacterial
proteins are synthesized chromosome by recombination
Figure 10.17
18. Viral Infections
Retrovirus: Genetic information is RNA
Produces DNA copy and creates a
prophage Envelope
Glycoprotein
Protein coat
Example:
RNA (two
HIV/AIDS identical strands)
Reverse transcriptase
19. 19.3 Diseases Caused by
Bacteria and Viruses
Pathogens- disease causing agents
Bacterial Disease
Viral Diseases
20. Diseases Caused by Bacteria
How does bacteria produce disease?
Damage the cells and tissues by breaking
down the cells for food
Releasing toxins (poisons into the body)
23. Diseases Caused by Viruses
Viruses disrupt the body’s normal
equilibrium
Cannot be treated with antibiotics
Viruses can infect humans and plants
24. Viruslike Particles
Viroids- single stranded RNA molecule
with no capsid
They cause diseases in plants
Infect cell and produce more viroids by
disrupting the plant metabolism
25. Viruslike Particles
Prions- contain only protein; no DNA or
RNA
They cause diseases in animals and
humans
Prions clump and cause normal protein to
clump with it- creating new prions