What are Bacteria? Bacteria are PROKARYOTES –The smallest known living cells They are found...
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Transcript of What are Bacteria? Bacteria are PROKARYOTES –The smallest known living cells They are found...
What are Bacteria?• Bacteria are PROKARYOTES
– The smallest known living cells
They are found
everywhere!!
Bacteria onhead of a pin Starr, 317
Bacteria in dental plaque microbeworld.org
Did you know? There are over 80 species of bacteria in your mouth!
Some cause diseaseWe call these “pathogens”
Anthrax, as seen by Koch microbeworld.org
But most are beneficial
Bacteria ferment cheese Schraer, 641
Characteristics of Bacteria
Most have a cell wall Many have a capsule (jelly
or slimy coating outside the cell wall, for protection)
They have a single, circular chromosome.
Some have plasmids (tiny rings of DNA separate from the chromosome.)
Cytoplasmic Pili help them talk to other cells.
Schraer, 632
Some have flagella - made of rope-like proteins, not microtubules.
Some slide on a slimy secretion.
Many can form dormant
cells called endospores to survive harsh conditions.
Salmonella www.iwate.jp
Streptomyces spores
Many can MOVE
Three basic shapes
• Spherical – coccus
• Rod – bacillus• Coiled - spirillum
Schraer, 633
Simple Colonies Staphylo = clusters
Strepto = chains
Staphylococcus wisc.edu
Diplo = double
Diplococcus
cat.cc.md.us
Streptobacillus
Reproduction in bacteria
• Purpose is to make more bacteria. It is considered ASEXUAL REPRODUCTION because only one cell is needed.
• In this process the bacteria splits into two to create more cells.
• It is known as binary fission.
Normal bacterial reproduction 1) chromosome replicates 2) copies separate as cell wall lengthens 3) cell membrane pinches in 4) septum/new wall grows 5) cells divide
Steps in binary fission maricopa.edu
Bacillus dividing by fission SixKingdoms.html
Binary fission (for a quick clone)
How Bacteria Populations Grow!!
Growth Curve (in Culture)
Schraer, 634
See Fission in Action
•
• Did you know? In ideal conditions, some species can divide every 10 MINUTES.
What stops them?
They run out of food or space, or wastes build up and poison them.
Nutrition
Most are heterotrophs - saprobes or parasites
Autotrophs -photosynthetic or
chemosynthetic
Did you know? Chemosynthetic bacteria are the base of the food chain at ocean floor vents.
Little is Better!!
Metabolism is FAST Bacteria can absorb nutrients and secrete wastes rapidly because of high
surface-to-volume ratio
Did you know? Lactose fermenters break down 10,000 times their weight in lactose in an HOUR!
Two Kingdoms of Bacteria
• Kingdom Archaebacteria
- “Ancient”, most primitive earliest known form of life
- •Kingdom Eubacteria - includes bacteria and cyanobacteria (blue-green)
Fluorescent micrograph of an archaeon microbeworld.org
Kingdom Eubacteria
Photosynthetic – 2 groups 1) cyanobacteria (aerobes)
–Have chlorophyll a and phycocyanin (blue)–Other colors, too–Most live in fresh water–Others live in salt water, soil and lichens
Starr, 315NostocSchraer, 637
More photosynthetics
2) green-sulfur and purple bacteria - anaerobic
- colors range from pink to black - photosynthesize without
water - make no oxygen - live in pond and sea mud
Biologic Importance of Bacteria
1) Essential to nutrient cycling2) Decomposers – in soil, inside animals Enterobacteria – live inside us, break down waste, make vitamins3) Process foods – cheese, yogurt, pickles4) Some MAKE antibiotics (streptomyacin)5) Used in cell and molecular research, genetic engineering, medical
research..
Sources• Schraer and Stoltz, Biology, the Study of Life, 7th ed. Prentice-Hall, 1999• Starr, Cecie, Biology, Concepts and Application, Wadsworth Group, 2003• Fission www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookmito.html www.biology.hawaii.edu/bio171/Notes/Bacteria/page6.htm• Archaebacteria http://biology.com/learning/archaea/introduction.html• Staphylococcus http://www.bact.wisc.edu/Bact330/lecturestaph• Conjugation http://tidepool.st.usm.edu/crswr/bactconjug.html• Legume nodules http://www.danieldeepak.com/bacteria.htm• Salmonella http://www.office.pref.iwate.jp/~hp1002/eiseika/salmonella.jpg• Bacteria reproducing
http://marshallteachers.sandi.net/teacher_sites/mcquillan/04.Classification/Readings/SixKingdoms.html
• Dental plaque http://www.microbeworld.org/htm/aboutmicro/microbes/types/.htm
• Fission time-lapse http://www.cellsalive.com/ecoli.htm• Diplococcus
http://www.cat.cc.md.us/courses/bio141/labmanua/lab16/diplo.html