bacteria notes
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Bacteria Notes. Basic Definition. karyo. Pro. Bacteria : Prokaryotic Organisms Pro : Primitive or “prior to” Karyon : Nucleus or “kernel” Single-celled organisms without a nucleus Has circular DNA - PowerPoint PPT PresentationTRANSCRIPT
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Bacteria Notes
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Basic Definition• Bacteria: Prokaryotic Organisms– Pro: Primitive or “prior to”– Karyon: Nucleus or “kernel”– Single-celled organisms without a nucleus – Has circular DNA – Often has “plasmid” DNA that helps codes for genes to
increase fitness (ex. Antibiotic resistance)– Bacteria can be measured in micrometers• 0.000001m or 10-6
Prokaryo
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What are the two groups of bacteria?
1. BacteriaCell walls with peptidoglycan
2. Archaebacteria• Cell walls lack peptidoglycan• Adapted to extreme environments:
Extremely hot and cold, salty, without oxygen, etc.
peptidoglycanMade up of types of peptide and sugar bonds
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What are the basic shapes of bacteria?
– Rod-shaped (Bacilli)Bacillus anthracis (Anthrax), Yersinia pestis (Bubonic plague)
– Comma-shaped (Vibrios) Vibrio cholerae– Spherical (Cocci)
Streptococcus, Staphylococcus– Spiral (Spirilla)
Treponema pallidum (Syphillis)
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Bacterial Staining• Gram-positive: Retains the crystals of violet dye in the
peptidoglycan of the cell wall.
• Only has an inner layer of plasma membrane
• Infection by this type can be treated by antibiotics such as penicillin, which attacks the peptidoglycan of the cell wall.
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• Gram-negative: Will not pick up much the violet dye because the cell wall is covered by an additional outer membrane, and instead appears pink.
• Infection by this type must be treated by a broad-spectrum antibiotic such as ciprofloxacin that enters bacteria and disrupts protein synthesis
Bacterial Staining
Peptidoglycan
Outer membrane
Inner membrane
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What is a plasmid?• Plasmids are circles of DNA that can replicate
separately from the main bacterial DNA.• Plasmids may carry genes that allow bacteria
to survive exposure to antibiotics.
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Bacterial Growth and Reproduction• Binary Fission: (video)
-Asexual division-DNA replicates and cytoplasm divides-Creates two genetically identical cells from one parent cell
• Conjugation: (video) -Not true sexual reproduction
-Sex pilus extends between bacteria -Plasmid DNA is transferred from one bacterium to another to introduce genetic diversity
• Spore Formation:-Occurs when growth conditions are unfavorable-An endospore is a “spore” with a thick internal wall of membrane that encloses and protects its DNA