Taxonomy – the 5 Kingdom System

• One of the purposes of taxonomy is to discover an organism’s PHYLOGENY – or evolutionary history.

• We will be following organisms through the “evolutionary family tree”, always keeping the phylogeny of the different phyla in mind.

Monerans: Prokaryotic

Cells• commonly

called bacteria

Structure:

• Prokaryotic cells are not as complex as eukaryotic cells. They do not have a nucleus and they only have a few simple organelles

• They have a cell wall and a cell membrane, cytoplasm and ribosomes. Their genetic material (DNA or RNA) is circular. Some of the monerans move around by means of a tail-like flagella

Comparison

Structure of

Prokaryotic Cells

Identifying Monerans:

• 1. Cell Shape • a. Rod-Shaped

“Bacillus”

Bacillus – Electron micrograph

Bacilli ( gram negative)with Flagella

Bacilli with Pilli

Comparative Size – RBC’s and Bacteria

A – RBCB – WBCC - bacteria

b. Spherical – “Cocci”

• “Cocci”

Streptococcus

Sometimes, cocci will form chains

c. Spiral Shaped “Spirillum”

Under our microscopes, it is difficult to distinguish between

these 3 shapes.

Under TEM

Under our Microscopes

2. Cell Walls • Bacteria cell walls can be stained by either CRYSTAL VIOLET (purple) or SAFRANINE (red). These stains are called GRAM stains. If the bacterium picks up the purple stain, it is considered GRAM POSITIVE. If the bacterium picks stains red, it is considered GRAM NEGATIVE.

Gram Staining Overview

• 1. Wash slide

• 2. “Fix” bacteria to slide

• 3. Flood with Crystal Violet

• 4. Leave 1 minute

• 5. Rinse with water

• 6. Flood with gram’s iodine

• 7. Decolorize with Ethanol

• (gram (-) loose color)

• 8. Counterstain with Safranin – 30 seconds

• 9. Rinse with water, air dry

3. Bacterial Movement

• We can also distinguish between different types of bacteria by how they get around.

• Types of movement include:

Whipping it’s flagella, gliding along a slime layer, slithering along like a snake and spiralling forward like a cork-screw.

Diversity of Bacteria• Some are autotrophic

– either phototrophic or chemotrophic. (chemotrophic use inorganic molecules like hydrogen sulphides, nitrites or iron to make energy. They live in harsh environments)

Chemosynthetic Ecosystems

• In a normal marine ecosystem, the organisms found at the bottom of the food chain are seagrass and phytoplankton, which produce energy through photosynthesis (a photosynthetic ecosystem). In environments rich in methane and sulfides, one type of food chain relies on chemosynthetic bacteria as basic producers. These include sulfur-oxidizing bacteria, methane-oxidizing bacteria, and sulfide-reducing bacteria. Such an environment is referred to as a chemosynthetic ecosystem.

• A special characteristic of a chemosynthetic ecosystem is its large biomass, despite its location in the deep sea.

Diversity

• Some are HETEROTROPHIC (like humans are). This means that they ingest organic molecules, and digest them to release the energy.

Diversity• Some are OBLIGATE AEROBES (like us); they

would die without oxygen.

Diversity• Others are

OBLIGATE ANAEROBES; they would die in the presence of oxygen.

(example of this is C. botulinum – causes botulism)

• Finally, some bacteria are FACULTATIVE ANAEROBES; these bacteria can live with or without oxygen.

Bacterial Reproduction

• 1. Binary Fission. (a form of asexual reproduction)

2. Conjugation

• (a form of sexual reproduction).

• A protein bridge is formed between the two bacteria through which the donor bacterium sends part of it’s genetic material to the recipient.

3. Spore Formation • When conditions are

unfavourable, the bacterium might create a thick, internal wall around it’s genetic material and some cytoplasm. This ENDOSPORE can remain dormant for an indeterminate amount of time, waiting for more favourable conditions again

The 4 Phyla of MONERA

• 1. Eubacteria:• The “true” bacteria• This is the largest

group of bacteria (in numbers, not size!)

2. Cyanobacteria

• The “blue-green algae”. (this is a mis-nomer – algae are EUKARYOTIC cells). Thes are autotrophic, but us a more primitive form of photosynthesis than found in higher plants.

3. Archaebacteria• These APPEAR

to be the most primitive, ancient forms of bacteria. However, on closer examination, they are more closely related to eukaryotic cells than they are to other prokaryotic cells.

• Archaebacteria live in the HARSHEST of conditions – high temperatures, high salinity (halophilic), oxygen free (anaerobic), chemosynthetic, etc.

Archaebacteria – A halobacteria (Lives in high

salinity)

• they color the salt flats of desert playas and evaporation ponds a pinkish-red. This is in Owens Lake CA. Owens Lake was once a vast blue lake, before it was drained (by diverting Owens River) to provide LA with water. Today it is a pinkish-red, dry lake bed teaming with salt-loving archaebacteria. A drop of brine contains millions of tiny bacilli swimming among crystals of NaCl.

• Archaebact. At high temperatures. Yellowstone National Park

High Salinity - Great Salt Lake, Utah(aerial view)

4. Prochlorobacteria• These bacteria have

chlorophyll a and chlorophyll b which makes them very similar to chloroplasts found in higher plants.

Host – a tunicate

Bacteria in Our World:• Food Production –

bacteria are used to produce cheese, yogurt, sour cream, vinegar, etc.

Lactobacillus acidiphilus and Streptococcus thermophilis (1000X)The bacteria that make Yogurt

Industry: • Bacteria can digest some petroleum, remove waste products from water, mine minerals from the ground and can produce some drugs (like insulin).

Thiobacillus ferrooxidans extracts copper from low-grade copper ore

Oil-Spill Treatment

• Species from all of the 4 other Kingdoms are dependent on bacteria in symbiotic relationships with different bacteria

• Ex: lichen:

bacteria and fungus

• Termites, are composite organisms.  The protist at left is just "one" of hundreds of thousands of microbes that live symbiotically within the termites digestive tract, and it is actually composed of at least 5 different organisms.  The "hair-like" projections are actually several different species of spirochete and bacillus bacteria that seem to function in movement.  Still other bacteria live within the protist cell, releasing energy from the food that it absorbs while other bacteria produce the enzymes necessary for digestion of the cellulose and lignin fibers that are the main components of wood.

• Some bacteria are saprophytes (organisms that obatin their energy and nutrients from “once-living” material). We depend on their ability to decompose organisms after they have died. They are also responsible for the decomposition of our sewage.

• Some plants are dependent on bacteria for “nitrogen fixation” – they are able to trap the nitrogen from the air into ammonia (NH3) and nitrate (NO3

-). Plants can use these forms of nitrogen, but are unable to use nitrogen from the air

• ** there are far more beneficial bacteria in this world than pathogenic bacteria***

• Pathogenic bacteria cause us grief in two ways: damaging cells and releasing toxins (staphylcoccus infection - impetigo

• We have learned many techniques to sterilize our environments and our foods by using high temperatures and disinfectants.

• Medicine is able to prevent bacterial infections using vaccinations.

• We also have antibiotics – drugs that kill bacteria specifically.