BACTERIA

BACTERIA

Bacilli

• Exists as single cells, in pairs (diplobacilli), and in chains (streptobacilli).
• May have flagella

Kingdom Archaebacteria

Spirillum

• Earliest forms of life on Earth.
• Live in environments where other organisms cannot survive.
• Environments have little or no oxygen (anaerobic)
• Cell walls lack peptidoglycon.

Coccus

Reproduction

• Found in water environments
• A spiral - shaped bacterium.
• Exist only as single cells.
• Have bipolar tufts of flagella.

Binary fission – a type of asexual reproduction where a bacterial cell divides in half, producing identical “daughter” cells

Conjugation – a form of sexual reproduction where bacteria exchange genetic information before dividing.

- offspring have new genes (and new traits)

Transformation - bacteria incorporate genes from other bacteria.

Introduces a foreign plasmid into a bacteria. ( Ex: resistance to antibiotics

Major groups of

Archaebacteria:

Bacteria may have extra pieces of DNA (called plasmids) in the cytoplasm.

Plasmids may include genes for resistance to antibiotics.

• Methanogens (methane-producing)
• Extreme thermophiles (live at temperatures up to 110 0C)
• Extreme halophiles (live in very salty water).

Vibrio

• Curved bacteria (boomerang shape)
• Vibrio cholerae causes cholera.

Endospores

• Single cells - monococci
• Pairs – diplococci
• Chains – streptococci
• no flagella

Transduction - Viruses insert new bacterial genes into a different bacterial cell

Endospore – when a bacterium forms a tough wall that encloses the DNA & some cytoplasm; allows it to survive harsh conditions

Spirochete

• Tight spiral shape.
• Located in soil, sewage, decaying matter, human and animal bodies.
• Causes Lyme disease, syphilis and rat bite fever.
• Helps digest food in cows.

Bacteria...

Prokaryotes

• bacteria live in nearly every environment on earth
• bacterial cells in the human body outnumber human cells 10 to 1
• there can be good and bad bacteria

PRO rhymes with NO

Autotrophs can make their own food:

A) Photosynthetic - use a special type of chlorophyll called bacteriochlorophyll.

-O2 is released in bacterial photosynthesis

B) Chemosynthetic - obtain energy by breaking down inorganic material such as iron or sulfur.

• Single-celled organisms
• NO nucleus
• NO membrane bound organelles
• Used to be in a single kingdom – Monera
• Are now divided into two kingdoms:

-Archaebacteria

-Eubacteria

How Bacteria GET

Energy

3 Shapes of Bacteria

ie: nutrition

Cocci

Bacilli

Spirilla

-Spiral shaped

-Spirillum (sing) Spirilli (pl)

-rod-shaped

-bacilli (pl.) bacillus (sing.)

-Spherical

-Cocci (pl.) coccus (sing.)

basilisk

bacillus

Can either be heterotrophs or autotrophs

Domain Bacteria

Stages of Growth

Identifying Prokaryotes

Identifying Prokaryotes

(cont.)

1)Their shape

-Bacilli – rod shaped

-Cocci – spherical

-Spirilla – spiral shaped

2) Their cell wall

-Gram-positive – appear purple

-Gram-negative – appear red

3) The way they move

-flagella, wiggling, or don’t move at all

• all are single-celled prokaryotes
• some are anaerobes; some are aerobes
• some photosynthesize
• play a vital role in the ecosystem as decomposers
• many cause diseases

1) Lag Phase

2) Log Phase

3) Stationary Phase

4) Death Phase

How Bacteria RELEASE

Energy

ie: respiration

Heterotrophs must get their food from ingesting a source of pre-formed organic matter:

(A) Saprobes- feed on the remains of dead plants and animals.

(B) Parasites - live on or in the organism and cause disease. For example, Mycobacterium tuberculosis.

Kingdom Eubacteria

The growth of bacteria is limited by the following factors:

- temperature

- pH

- moisture content

- nutrient availability

- competition from other organisms

Beneficial Effects of

Bacteria

1) LAG PHASE: Growth is slow at first. Bacteria acclimate to the food and nutrients in their new habitat.

2) LOG PHASE: multiplying exponentially, doubling in number every few minutes.

3) STATIONARY PHASE: more competition for dwindling food and nutrients, booming growth stops and the number of bacteria stabilizes.

4) DEATH PHASE: Toxic waste products build up, food is depleted and bacteria begin to die.

• Obligate aerobes – organisms that require oxygen for respiration
• Obligate anaerobes – organisms that do not require oxygen and may be poisoned by it
• Facultative anaerobes – can survive with or without oxygen

• cells are much smaller than plant and animal cells
• 2000 different species of bacteria.
• Reproduce by binary fission.(splitting in half)
• live almost anywhere
• cell walls contain peptidoglycan

When oxygen is absent, both obligate and

facultative anaerobes obtain energy by fermentation

Fermentation - the chemical breakdown of a substance, producing carbon dioxide and alcohol

Harmful Effects of

Bacteria

• Pathogens – disease-causing agents
• Bacteria cause disease such as tuberculosis, strep throat, pneumonia and cholera
• Bacteria cause disease in one of two ways:

-Damage tissues by breaking them down for food

-Release toxins (poisons) that harm the body

• Decomposers – break down dead matter into reusable nutrients
• Nitrogen fixers – convert nitrogen gas into a form that is usable by plants
• Humans use bacteria to make certain foods – yogurt, cheese, sour cream
• Can be used in industry to clean up waste products & oil spills

What is Antibiotic Resistance?

- ability of bacteria to resist antibiotics

-

Resistance to Antibiotics

Antibiotics – chemicals that block the growth & reproduction of bacteria