Download Bacteria Bacteria are classified into 2 Kingdoms Eubacteria

Bacteria
Bacteria are classified into 2 Kingdoms
 Eubacteria- larger of the 2 kingdoms, large variety of organisms
 Archaebacteria- chemically different than eubacteria, live in extreme environments
Bacteria- all are prokaryotic organisms
Prokaryotic classification:
 Shape- bacilli (rod-shaped), cocci (sphere-shaped), spirilla (spiral and cork screw shaped)
 Cell walls – 2 types of cell walls in eubacteria determined by Gram staining
o Gram-positive bacteria stain purple because they have peptidoglycan in their cell wall
o Gram-negative bacteria stain red because they have thinner cell walls
 Movement- some bacteria are non-motile while others have whiplike structures that propel them
forwards or glide them slowly along like a slimelike material they secrete
 Metabolic Diversity –
o Chemoheterotrophs – take in organic molecules for energy
o Photoheterotrophs – use sunlight and photosynthesis for energy, but must also take in organic
molecules for energy.
o Photoautotrophs – use light energy and photosynthesis to create their energy
o Chemoautotrophs – use carbon dioxide to make energy, but do not require light energy.
 Energy Release –
o Obligate aerobes – require a constant supply of oxygen for life
o Obligate anaerobes – must live in the absence of oxygen
o Facultative anaerobes – can live with or without oxygen, but most live without oxygen.
 Growth and Reproduction –
o Binary Fission – mitosis of a single cell organism
o Conjugation – the exchange of genetic information from one bacterial cell to another
o Spore Formation – used with growth conditions are unfavorable. Spores can sit until growth
conditions are favorable and then reproduce.
Importance of Bacteria:
 Decomposers
 Nitrogen Fixers – changes nitrogen gas to ammonia ( a useful form of nitrogen)
 Human Uses
 Makes Food and Beverages
 Removes Waste products and poisons from water
 Makes drugs and chemicals
 Live in our intestine and make vitamins our bodies can’t make
Viruses
Viruses – particles of nucleic acid, protein and sometimes lipids that can reproduce only by entering a cell
 Composed of DNA or RNA surrounded by a protein coat called a capsid
 The capsid is what allows a virus to enter the cell
 Can infect bacteria – these viruses are called bacteriophages
Viral infection:
 Lytic infection – virus enters a cell, makes copies of itself and causes the cell to burst (kills host)
 Lysogenic infection – virus integrates its DNA into the DNA of the host cell, then the viral genetic
information replicates along with the host cell’s DNA. The cell does not burst.
o The viral DNA embedded in the host cell DNA is called prophage
Retroviruses – viruses that contain RNA as the genetic information
 Infect a cell and then produce a DNA copy of their RNA
 That DNA copy then, like a prophage, integrates with the host’s cell DNA
 EXAMPLE: HIV