Download Bacteria and ArchaeBacteria

Kingdom Eubacteria and Kingdom Archaebacteria
Prokaryotes
Characteristics of Bacteria
• Bacteria are by far the most abundant organisms on Earth.
• As a group they are very diverse, but they all share certain characteristics.
Characteristics of Bacteria
1. All bacteria are single‐celled.
2. All bacteria are prokaryotes:
DNA and the cell organelles are not surrounded by a membrane.
3. The DNA of bacteria is made of a single chromosome.
4. All bacteria reproduce asexually by binary fission.
Bacteria
• Bacteria are the smallest organisms. • They are usually 1–10 microns
• A typical eukaryotic cell is about 10 times larger. Structure of a Bacteria
The structure is simple:
• Cell wall: provides support and protection for the contents of the cell. • Cell membrane controls the passage of materials into and out of the cell.
Structure of a Bacteria
• The structure is simple:
• The cytoplasm contains ribosomes, responsible for the formation of proteins
• The DNA is a single chromosome formed into a ring
• There is roughly 1/1000th the amount of DNA than in a typical eukaryotic cell. Projections Provide Locomotion
• Some bacteria have whip‐like flagella (singular: flagellum). • They act like propellers moving in reverse, drawing the organism forward.
• Some bacteria have cilia (also called pili), tiny hair‐like structures on the surface of the cell
• They beat to move the bacteria forward
• http://www.youtube.com/watch?v=QGAm6hMysTA
Cell shape
• spherical cell is called a coccus (pural: cocci)
• a rod shaped cell is called a bacillus (plural: bacilli)
• a spiral‐shaped cell is called a spirillum (plural: spirilli).
More names
monococci: cocci that live as separate cells
Diplococci: cocci that live in pairs.
Streptococci: cocci that live in linear chains
Staphlococci: cocci that live in grapelike clusters
Bacilli also exist as single cells, pairs (diplobacilli), or chains (streptobacilli). • Spiralbacteria exist only as single cells.
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Nutrition
• There is a large variety of nutritional patterns among bacteria. Respiration
• All living things must carry out cellular respiration to receive a supply of energy for life’s functions. • Bacteria differ in whether or not they require oxygen.
Respiration
• If cellular respiration involves oxygen to produce energy, bacteria are termed aerobes.
• If oxygen is absolutely necessary for their survival, they are called obligate aerobes.
Respiration
• Those bacteria that can carry out cellular respiration in an oxygen‐free environment are termed anaerobes. • If the presence of oxygen kills these organisms, they are called obligate anaerobes.
• A third group of bacteria can survive with or without oxygen and they are called facultative anaerobes.
Reproduction
• All bacteria reproduce asexually and divide
by the process of binary fission
Reproduction
• Bacteria can reproduce in 15 to 20 minutes as long as there is sufficient food, warmth, and space.
• Under the right conditions, a single E.coli bacterium can produce between 10 and 100 million bacteria in 12 hours.
Conjugation‐ sexual reproduction
During conjugation, two bacterial cells connect to each other by long protein bridges • The plasmid (ring of extra DNA) of one cell is transferred to the other cell. • When the process is completed, the bacterium that received the genetic material from the other cell now has a different genetic makeup
• Having an altered genetic makeup increases the chance that a bacterium might possess a gene combination that enables the organism to adapt to worsening conditions.
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Bacteria and Disease
• Only a small percentage of prokaryotes are pathogenic, or disease causing.
• Pathogenic bacteria produce deadly substances (toxins) in the human body that cause disease symptoms.
The Two Kingdoms of Bacteria
• There are two kingdoms of bacteria:
– Archaebacteria in the domain Archea
– Eubacteria in the domain Bacteria
Achaebacteria
Archaebacteria
• Most archaebacteria live in extreme environments. These are called extremophyles. • Other Archaebacteria species are not extremophiles and live in ordinary temperatures and salinities. Some even live in your guts!
Archaebacteria
• Some extremophile species love the heat! They like to live in boiling water, like the geysers of Yellowstone Park, and inside volcanoes.
• These are called "thermophiles" which means "loving heat", and it would probably freeze to death at ordinary room temperature.
Archaebacteria
• Other extremophile Archaea live in very salty, called hypersaline, environments. These salt‐loving Archaea are called halophyles.
• Other achaea are known as methanogens. • Methanogens are methane producers. Most of these bacteria use carbon dioxide as their carbon source. They are found in soil, swamps, and most animals digestive tracts Eubacteria
• Eubacteria are more common and more widespread than acheabacteria.
• There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water
• There are approximately five nonillion (5×1030) bacteria on Earth, forming much of the world's biomass.