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)