Bacteria and VirusesCh. 19
Eubacteria◦ Largest kingdom of living things◦ Live everywhere◦ Cell wall contains peptidoglycan
Archaebacteria◦ Cell wall lacks peptidoglycan◦ DNA sequences more similar to eukaryotes◦ Live in extreme environments
Classifying Prokaryotes
Shapes◦ Rod (bacilli)◦ Spiral (spirilla)◦ Spherical (cocci)
Identification
Cell walls◦ Gram-positive stained have peptidoglycan call
walls (violet)◦ Gram-negative lack peptidoglycan (red)
Movement◦ Variety of ways….
Identification
Heterotrophs◦ Chemoheterotrophs and photoheterotrophs
majority Autotrophs
◦ Photoautotrophs Cyanobacteria
◦ Chemoautotrophs
Metabolic Diversity
Obligate aerobes◦ Require oxygen all the time; aerobic respiration
Mycobacterium tuberculosis Obligate anaerobes
◦ Killed by oxygen; anaerobic respiration Clostridium botulinum
Facultative anaerobes◦ Can survive with or without oxygen; both types of
respiration Eschericia coli
Respiration
Binary fission◦ Mitotic; asexual
Conjugation◦ Gene swapping; sexual
Sporulation◦ When conditions become unfavorable DNA and a
little cytoplasm is enclosed in an endospore
Growth and Reproduction
Growth and Reproduction
Decomposers Nitrogen fixers Food industry Mining Cleaning oil spills Pharmaceuticals Oxy Clean
Bacterial Importance
Bits of DNA or RNA surrounded by a protein coat. That’s it.◦ They come in a variety of shapes and sizes◦ They must infect a host cell to reproduce.
◦ Bacteriophages are viruses that infect bacteria.
What is a Virus?
Viruses enter a host cell and use the cell’s machinery to reproduce.
◦ In lytic infections the virus reproduces immediately until the cell bursts.
◦ In lysogenic infections the viral DNA is incorporated into the host’s DNA as prophage and may remain dormant for a period of time until reproduction begins.
Viral Infection
Contain RNA instead of DNA◦ After infecting a cell the RNA is copied in reverse
to make DNA which is then incorporated into the host cell’s genome as prophage.
◦ RNA viruses mutate frequently. Rhino virus (colds) HIV
Retroviruses
Are viruses alive?
Bacteria and viruses can act a pathogens – disease causing agents (pathos = disease; gen = generating).
◦ Louis Pasteur helped formulate the germ theory of disease.
◦ Bacteria cause disease by either using cells for food or by releasing toxins (poisons) that are harmful.
Bacterial Diseases
Bacterial Diseases
Sterilization with heat Disinfectants Cold storage Vacuum packing Nitrogen/inert gases
Controlling Bacteria
Some target the cell wall of bacteria and others disrupt protein synthesis. ◦ Antibiotics are specific to the type of bacteria
they act upon.
Antibiotics
Can’t be treated with antibiotics! They don’t have a cell wall or make proteins…
◦ Best treatment is prevention; once infected it has to run its course. Symptoms may be treated.
Viral Diseases
Viral Diseases
Vaccines provide some protection and immunity to bacterial and viral diseases.◦ More to follow…
Prevention