eubacteria - science to a tee · eubacteria • found almost everywhere!! -oldest & most...
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Eubacteria
Eubacteria• found almost everywhere!! -oldest & most abundant of organisms! - 3.5 billion years ago
Characteristics of Bacterial Cells
Bacteria cells: • are prokaryotic • all single-celled • no membrane-bound nucleus or organelles • single chromosome
Characteristics of Bacterial Cells
Bacteria cells: • are prokaryotic • all single-celled • no membrane-bound nucleus or organelles • single chromosome • reproduce by binary fission (asexually)
Reproduction
1. Binary Fission -simpler than mitosis
- single strand of DNA replicates, cell mb & wall grows through midsection, cytoplasm is divided
2. Spore production
• Many reproduce by making tough resistant spores • Spores survive conditions bacteria can’t
3. Conjugation • cells link by a tube called a pilus • sharing of favorable genetic info. in a small DNA loop called a PLASMID
• results new bacterial strains
How Are Bacteria Classified??
Classified by Shape:
• spherical (cocci/coccus) • rod-shaped (bacilli/bacillus) • spiral (spirilla/spirillum)
- they can be alone or found in clusters
MonococcusDiplococcus
StreptococcusStaphlococcus
Classified by Type of Cell Wall (determined by staining)
Gram positive -no fatty envelop
Gram negative -contain an envelop
Classified by Type of Cell Wall (determined by staining)
• gram-positive (stain purple) • gram-negative (stain pink/red)
Classified by Respiration
• obligate aerobes - need oxygen for respiration
• obligate anaerobes - must have no oxygen
• facultative aerobes - prefer oxygen, but can live without
Are All Bacteria Harmful??
• Produce toxins - • Food spoilage - • Disease- • Recyclers + • Symbiotic with humans+ • Used in industry + • Produce O2 + • Fix Nitrogen +
Bacterial Resistance to Antibiotics
antibiotics - chemicals that prevent the growth of or destroy certain microorganisms
How does resistance develop?
How does resistance develop?
• when population are exposed to drugs, the weaker bacteria die
• others have variations in genetic material that allow them to survive ---> genes that code for enzymes ---> these enzymes inactivate drugs
• These resistant bacteria reproduce & voila resistance develops
• Transfer resistance to via conjugation.
C. Difficile
MRSA-(methicillin-resistant Staph aureus)