Bacteria Are Classified Into 2 Kingdoms

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