Bacteria

1
Bacteria
Kingdoms Archaebacteria Eubacteria (Formerly
Monera)
Domains Archae and Bacteria
2
What are Bacteria?

• Bacteria are PROKARYOTES
• The smallest known living cells
• Most are 0.1-0.5 mm in size

They are found everywhere!
Bacteria on head of a pin Starr, 317
Did you know? There are over 80 species of
bacteria in your mouth!
Bacteria in dental plaque
microbeworld.org
3
Some cause diseaseWe call these pathogens
Anthrax, as seen by Koch
microbeworld.org
But most are beneficial

Bacteria ferment cheese
Schraer, 641
4
Structure 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
5
Nucleoid
6
Many can MOVE, or go DORMANT
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. - tetanus,
anthrax
7
Three basic shapes

• Spherical coccus
• Rod bacillus
• Coiled - spirillum

Schraer, 633
8
Simple Colonies

• Staphylo clusters

• Strepto chains

Staphylococcus
wisc.edu Diplo
double
Diplococcus
cat.cc.md.us

Streptobacillus
9
Asexual Reproduction Binary fission
Normal bacterial reproduction 1)
chromosome replicates 2) copies separate as
cell wall lengthens 3)
cell membrane pinches in 4) cells divide
Steps in binary fission
maricopa.edu
Bacillus dividing by fission
10
Cell Respiration

• Most are obligate aerobes
• Others are facultative or obligate
  anaerobes.
• Anaerobes make a variety of fermentation
  products
• acids, alcohols, methane gas
• food products

11
bacteria reproducing
12
See Fission in Action

• Did you know? In ideal conditions, some
  species can divide every 20
  MINUTES.
• What stops them?
• They run out of food or space,
• or wastes build up and poison them.

13
Sexual Reproductionconjugation

• Two bacteria connect by a cytoplasmic bridge
• Donor copies passes DNA to recipient
• Recipient now has new genes

Common way to transfer antibiotic resistance!!
14
Two more sexual reproductions

• TRANSDUCTION
• virus inserts DNA into bacterium
• Prophage contains new genes
• TRANSFORMATION
• Bacterium takes in plasmids or DNA fragments from
  environment
• Plasmids contain new genes

15
Sexual reproduction in bacteria
16
Two Kingdoms of BacteriaDiffer in their chemistry

• Kingdom Archaebacteria
• - Ancient, most primitive
• earliest known form of life
• -

17
Archaebacteria

• Differ chemically from Eubacteria
• Eubacteria have cell walls with peptidoglycan
• Archaebacteria have other polysaccharides
• Ribosomes, lipids, enzymes are also different
• Archaebacteria are
  more chemically like
  Eukaryotes like us!

RNA polymerase enzyme
18
Archae are extremophiles

• Live in habitats like early earth
• Too harsh for most organisms
• 1) methanogens decomposers,
• live in animal intestines, swamps bogs,
  sewage treatment
• 2) Halophiles salt
• 3) Thermophiles hot
• 4) Acidophiles acid

Acidophiles acid pools
19
Archaea are Extremophiles
Halophiles Great Salt Lake, Dead Sea
Thermophiles deep sea vents
Thermophiles hot springs, geysers
20
Kingdom Eubacteria

• Ordinary bacteria
• Many decomposers
• Some autotrophs
• Nitrogen suppliers
• Pathogens

21
Heterotrophic Bacteria

• 1) Nitrogen-fixing bacteria
• a) Fix (change chemically) nitrogen gas from
  the air into a form plants can use
• b)need nitrogen to make proteins, nucleic
  acids
• c) live in soil and in legume plants
• clover, peanuts,
• soybeans,

Legume roots nodules contain
nitrogen-fixing bacteria
22
Decomposers

• Essential to nutrient cycling
• In soil
• Return inorganic chemicals to soil
• Plants take up chemicals and make food
• Some bacteria return nitrogen gas to the air
• Inside animals
• Enterobacteria live inside us,
• break down waste, make vitamins

23
E. Coli (enteric bacteria)
24
Photosynthetic bacteria

• Cyanobacteria
• Have chlorophyll a (green)
• and cyanin (blue)
• Most live in fresh water
• Some in salt water,
• soil and lichens

Starr, 315
25
Blue-green bacteria often link together, forming
filaments
26
Blue-green bacteria are major producers in
aquatic ecosystems
27
Some blue-green bacteria live with fungi in a
symbiotic organism - lichen
28
Chemosynthetic Bacteria

• Producers on ocean floor
• Use heat and chemicals from thermal vents
• Live inside giant tube worms

29
Human Uses for Bacteria

• Food culture (yogurt, cheeses, vinegars)
• Bioremediation (clean up poisons, oil spills)
• Gene engineering
• Source for antibiotics (ex. Streptomycin)
• Water treatment
• Drug development
• Medical, genetic research

30
Pathogenic Bacteria

• Many groups and types, but divided into
  two classes by GRAM STAIN

Schraer 637
Gram negative Pink - Cell wall resists
stain Harder to treat if
pathogenic
Gram positive Purple Respond to normal
antibiotics
31
The Germ Theory of Disease1800s

• Louis Pasteur - microscopic organisms were the
  cause of many human diseases
• Robert Koch - devised a set of steps to identify
  the organism responsible for an illness Kochs
  Postulates
• Joseph Lister sterile technique

32
Some Bacterial Diseases
Salmonella tetanus diptheria
Strep throat
tuberculosis MRSA
33
How do bacteria make us sick?

• 1) some make toxins that kill cells or
  interfere with their function
• Botulism, salmonella, cholera
• 2) some kill cells directly
• 3) some reproduce so fast their numbers
  interfere with organ function

34
How Bacteria Populations Grow!!
Growth Curve (in Culture)

Schraer, 634
Why do they die out? Run out of food, or wastes
build up
35
How do we fight bacteria?

• Antimicrobial Agents - chemicals that inhibit
  bacterial growth
• a) antiseptics on living tissue (skin)
• b) disinfectants on nonliving surfaces
• c) antibiotics inside living organisms
• - damage molecules needed when cells divide
• - cell wall (penicillin) proteins
  (tetracycline)

36
What are prions?

• Prions are misfolded protein molecules that can
  cause disease
• - no DNA (not a virus)
• - they induce normal proteins to misfold
• - cause loss of tissue/organ function? death
• - ex. Mad Cow Disease (brain)
• - Creutzchfeldt-Jakob Syndrome in humans
• - get it from eating contaminated meat

37
What are viroids?

• Circular pieces of RNA
• No protein or membrane coat (not a virus)
• Can cause disease, more often in plants
• Only human example hepatitis D

38
A misfolded protein
39
Little is Better!!

• Most prokaryotes measure 0.5-1.0 mm
• 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!

40
Kingdom Archaebacteria

• Why a separate kingdom?
• Archae differ chemically from other bacteria.
• 1) cell wall - different amino acids and
  sugars.
• Eubacteria have peptidoglycan
• Archaebacteria have varied
  polysaccharides
• but not peptidoglycan.
  
• 2) membrane lipids
• 3) ribosomes
• 4) enzymes - - - - - - - - - - - - gt
• 5) cytochromes
• 6) gene sequences . . . And MORE

RNA polymerase
41

• 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

42
Nutrition

• Most are heterotrophs
• - saprobes or parasites
• Some are Autotrophs
• -photosynthetic or chemosynthetic
• Did you know? Chemosynthetic bacteria are the
  base of the food chain at ocean floor vents.

43
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/BIOB
  K/BioBookmito.html
• www.biology.hawaii.edu/bio171/Notes/Bacteri
  a/page6.htm
• Archaebacteria http//biology.com/learning/archaea
  /introduction.html
• Staphylococcus http//www.bact.wisc.edu/Bact330/le
  cturestaph
• Conjugation http//tidepool.st.usm.edu/crswr/bactc
  onjug.html
• Legume nodules http//www.danieldeepak.com/bacteri
  a.htm
• Salmonella http//www.office.pref.iwate.jp/hp1002
  /eiseika/salmonella.jpg
• Bacteria reproducing http//marshallteachers.sandi
  .net/teacher_sites/mcquillan/04.Classification/Rea
  dings/SixKingdoms.html
• Dental plaque http//www.microbeworld.org/htm/abou
  tmicro/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