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