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In the three-domain system, two domains are prokaryotes (Bacteria and Archaea). Prokaryotes have no nucleus or membrane – bound organelles Bacteria - what your used to found everywhere Organisms in Archaea often live in extreme environments (thought to be the earliest forms of life)

The third domain is Eukarya

Bacteria exist in very large numbers almost everywhere on Earth - Your body has 10 times more bacteria cells than human cells!

Some bacteria are harmful, and some are helpful   - E.Coli live in your colon, but also are toxic when ingested

Helpful - cycle nutrients like carbon and nitrogen - cyanobacteria are very important producers in many water ecosystems

Bacteria are classified by their Shape, Cell walls and Motility. Shapes Spherical: a.k.a. coccus  - eg. Pneumonia-causing bacteria  - Cocci appear in clusters (Staphlococcus) or chains  (Streptococcus)

Rod-Shaped: a.k.a. bacillus - eg. E. Coli

Spiral: curved or spiral-shaped - eg. Lyme disease

Microviewer - harmful/helpful

Cell Wall Structure Nearly all bacteria have cell walls outside their plasma membrane, but they are very different than plant cell walls.- Type 1: Composed of peptidoglycan (thick coat of sugars)- Type 2: Thin coat of peptidoglycan, plus extra membrane

Movement About half of all bacteria cannot move on their own Methods of bacterial movement include:  - Flagellum- whip like tail (most common)      - Spiral bacteria twist like a corkscrew      - Some bacteria glide on a film of slime

Bacteria obtain their nutrition in a variety of ways Heterotrophs eat and autotrophs get energy from the Sun

Bacteria essentially live everywhere, in any type of environment cold, hot dry, wet acidic, neutral, basic w/out light w/out O2

Bacteria's main form of reproduction is binary fission One original cell splits into two This can occur in as little as 20 minutes Limiting factors like overcrowding, waste and food - food availability do not allow population to grow this large Produces colonies of bacteria that are genetically identical

Binary Fission Microviewer activity.

Binary Fission

Is cell division the same as reproduction?

Slide 4Has the nucleus become larger or smaller since division began?

Slide 5Do you see any evidence that the cytoplasm is getting ready to divide? 

Slide 6Can you describe what is happening to this part of the cell?

Slide 7Can you explain why in this case cell division accomplished reproduction? 

Slide 8Draw the correct sequence of binary fission using the culture of dividing paramecia.

Assume you started with one paramecium which divided three times daily. If you gave it the best conditions, and none of the offspring died, how many paramecia would there be in the culture at the end of a week?

To increase genetic diversity, bacteria undergo transformation, conjugation, or transduction

Transformation: bacteria pick up stray DNA from their surroundings

Conjugation: two bacterial cells join to exchange genetic material (plasmids, separate from main DNA)

Transduction: viruses that infect bacteria transmit genetic material from another source

Conjugation Microviewer Activity!

Conjugation

Slide 2How did the peculiar looking structure in the middle of the slide develop?

Why is sexual reproduction in the mold called conjugation rather than fertilization? 

Slide 5Can conjugation help explain the frequent appearance of new strains of disease germs which never existed before?

What additional form of reproduction is indicated by the furrow at F?

Slide 7What difference in activity distinguishes the male and female gametes?

Slide 8Which filament of cells was male? Which was female? What evidence can you present? 

Can you find evidence that all cells of one filament are of the same sex? How do you explain this fact?

Endospores form when environmental conditions make normal functions too difficult A small amount of cytoplasm and DNA form a tough capsule

Very difficult to get rid of or control bacteria growth ASEPTIC TECHNIQUES are used eg. Antiseptics – used on living tissue Disinfectants – used on surfaces Antibiotics – taken internally

To Prepare Agar for Bacteria Lab

1) Weigh 2.3 g of nutrient agar2) Measure 100 mL of water in a clean beaker.3) Add agar and heat solution.4) Stir continuously.

Groups of 3

Attachments

bacteria - YouTube.flv

Bacterial Conjugation - YouTube.flv