BACTERIA

1. Bacteria are classified into two kingdoms: Eubacteria (true bacteria) and Archaebacteria (Ancient Bacteria).2. BACTERIA are microscopic Prokaryotes.  (“before nucleus”)3. Adapted to living in all environments (even some extreme) – they exist EVERYWHERE

1. Outside the plasma membrane of most cells is a rigid cell wall that keeps the cell from bursting or collapsing due to osmotic changes by peptidoglycan, a complex molecule containing a unique amino disaccharide and peptide fragments. 

a. The cell wall may be surrounded by an organized capsule called a glycocalyx and/or by a loose gelatinous sheath called a slime layer. 

b. In parasitic forms, these outer coverings protect the cell from host defenses.

Bacteria Structure

5.  Nucleoid region contains a

circular loop of DNA

6.  Plasmids are rings of DNA,

used in reproduction

7.  Ribosomes in cytoplasm

synthesize proteins

2. Flagella is used for movement

3.  Pilli (Fimbrae) help bacteria

cling to surfaces

4. Prokaryotes do not have

organelles or a membrane bound

 nucleus!

Cell Membrane – regulates what comes in and out of the cell

Cell Wall – maintains shape and form

Capsule – found in virulent bacteria, helps evade immune system

Binary fission is the splitting of a parent cell into two daughter cells; it is asexual reproduction in prokaryotes. 

I

II.  Reproduction in Prokaryotes

In bacteria, genetic recombination can occur in three ways. 

a. Conjugation occurs when a bacterium passes DNA to a second bacterium through a tube (sex pilus) that temporarily joins two cells; the plasmid (DNA) is then exchanged

b.Transformation involves bacteria taking up free pieces of DNA secreted by live bacteria or released by dead bacteria. 

c. In transduction, bacteriophages transfer portions of bacterial DNA from one cell to another. Plasmids can carry genes for resistance to antibiotics and transfer them between bacteria by any of these processes

Plasmid – an extra bit of DNA,

used in sexual reproduction

Plasmids are also used in genetic engineering

Some bacteria form resistant endospores in response to unfavorable environmental conditions.

TRANSFORMATION

III.  Prokaryotic Nutrition  1.   Bacteria differ in their need for, and tolerance of, oxygen (O2).

a.   Obligate anaerobes are unable to grow in the presence of O2; this includes anaerobic bacteria that cause botulism, gas gangrene, and tetanus.b.   Facultative anaerobes are able to grow in either the presence or absence of gaseous O2.c.   Aerobic organisms (including animals and most prokaryotes) require a constant supply of O2 to carry out cellular respiration.

staphylococcus is a gram-positive, facultative anaerobe

2.   Autotrophic Prokaryotes

a.   Photoautotrophs are photosynthetic and use light energy to assemble the organic molecules they require.b.   Chemoautotrophs make organic molecules by using energy derived from the oxidation of inorganic compounds in the environment. (methanogens)

Check out the virus and bacteria gallery

THERMOACIDOPHILE – the red stuff on the rocks

This is an archaebacteria.

THE FUTURE BELONGS TO ARCHAE!

3.   Heterotrophic Prokaryotes

a.    Most free‑living bacteria are chemoheterotrophs that take in pre-formed organic nutrients.b.    As aerobic saprotrophs, there is probably no natural organic molecule that cannot be broken down by some prokaryotic species. c.    Detritivores (saprophytic bacteria) are critical in recycling materials in the ecosystem; they decompose dead organic matter and make it available to photosynthesizers.

Bacteria have an important role to play in breaking down materials in the environment.

Some are harmful and break down material we'd rather keep, like this image of an infection of necrotizing fasciitis (flesh-eating bacteria)

Bacteria Shape & Naming

The Gram stain procedure (developed in the late 1880s by Hans Christian Gram) differentiates bacteria.

a. Gram‑positive bacteria stain purple, whereas Gram‑negative bacteria stain pink.

b. This difference is dependent on the thick or thin (respectively) peptidoglycan cell wall.

Bacteria Shapes

Cocci – spheres

Bacilli – rods

Spirilla - spirals

Staph – in clusters

Strep – in chains

Streptococcus

Streptococcus

Strains are responsible for strep throat, and flesh eating bacteria

Staphylococcus aureus

Staph means “bunch of grapes” in greek.

Staph Infection

Tetanus

Rigid muscles from tetanus infection

Also known as “lockjaw”

Clostridium botulism

Gram positive

Causes food poisoning that is sometimes fatal

All forms lead to paralysis that typically starts with the muscles of the face and then spreads towards the limbs.[1] In severe forms, it leads to paralysis of the breathing muscles and causes respiratory failure. In view of this life-threatening complication, all suspected cases of botulism are treated as medical emergencies, and public health officials are usually involved to prevent further cases from the same source.[1]

A form of botulism is used in BOTOX treatments, as it paralyzes the muscles of the face and effectively smooths wrinkles.

Results may vary.

Yersinia Pestis

The black plague, this bacteria was carried on the fleas of rats.  It was responsible for the deaths of thousands of Europeans from the 8th to the 14th century.

Bacillis Anthracis (Anthrax)

Bacillus (unknown strain)

MycoplasmasCauses pneumonia

Rickettsia rickettsi

Rocky Mountain Spotted Fever, carried by ticks

E. Coli

Spirilla Bacteria

Salmonella

Plush Germs

Syphilis E. Coli

Gonorrhea

The Plague (Black Death)

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