Living Things1.7 million species been
classifiedsuggested around 8.8 million
speciesall are put into groups based on
genetics3 main domains (groups) are:Archaea & Eubacteria –
prokaryotesEukaryotes BiologySource
Prokaryotes – 2 KingdomsFormerly 1 kingdom - MoneraArchea – primitive bacteriaEubacteria – more developedearliest life on earthdiverged from common ancestor
~ 4 byaeukaryotes diverged millions yrs
later
Eukaryotes – 4 KingdomsPlant, Animal, Fungi, Protists
1. Archeacan live in extreme
conditionsthermophiles – hot
temp like hydrothermal vent
halophile – salty environments like Dead Sea
psycrophiles – live at cold temp (Antarctic lakes)
acidophiles – can tolerate pH 0
some live in normal temp and environments
most are methanogens – absorb CO2, N2, or H2S and give off methane
doesn’t require sunlight or oxygen
2. Eubacteria“true” bacteriamicroscopicex cyanobacteria (blue-green
algae) on earth for over 3 billion years
able to carry out photosynthesis (produces oxygen)
oxygen conc of atmosphere increased allowing oxygen breathers (animals) to survive
Uses of Eubacteriadigestion in intestinesyoghurt/cheese productionfermentation (wine, beer, pickling…)wastewater/oil spill/toxic spill treatmentBiologySourcedecomposers
Dangerous Eubacteriacause health
problems: strep throatfood
poisoning (E. coli and salmonella)
Structure & Function of Bacteria microscopic smallest living
cells classified
according to:1. cell shape2. cell wall
structure3. motility (way of
moving)
1. Cell Shape3 basic cell shapesspherical – “cocci”rod-shaped – “ bacilli”spiral – “spirochetes”
prefixes are added to show living arrangement of bacteria
strepto – chainstphlyo - cluster
CAN YOU NAME IT???
staphylococcus diplococcus
streptococcus
2. Cell Wall Structure2 kinds of cell walls, appear
different when stained with Gram stain
peptidoglycan – thick coat of sugars, makes wall strong & rigid (Gram postive)
less peptidoglycan (Gram negative)
Movementvarious methods:most mobile bacteria use flagella
(whip-like tail)others secrete mucous can glide
on
Typical Bacteria
How Bacteria Reproduce1. Asexual - Binary
Fission1 original cell splits into
2can occur in 20 minutes
for many bacteria species.
In 12 hours, 1 bacterium can divide to form a colony of 68 billion cells.
overcrowding, waste, and food availability do not allow populations to grow this large.
produces colonies of bacteria that are genetically identical.
2. Types of Sexual Reproduction
1. Transformation: bacteria pick up stray DNA from their surroundings.
2. Conjugation: two bacterial cells join (= conjugate) to exchange genetic material (plasmids, separate from main DNA)
3. Transduction: viruses that infect bacteria transmit genetic material from another sourceEndospores form when
environmental conditions make normal functions too difficult.
Viruses: Structure and FunctionViruses not
considered to be living organisms.◦have DNA and RNA,
and can adapt to change.
◦made of proteins and nucleic acids, not cells.
◦must use a host cell to reproduce.
See page 29
structure of virus allows it to enter host cell and reproduce◦ many shapes and sizes.◦ usually classified by the
type of cell they infect.◦ protein coat is like the
key to a specific cell membrane, e.g., HIV only infects T cells of the immune system.
◦ Sometimes, (avian flu virus) protein coat is a master key.
◦ Bacteriophages enter and infect bacteria, used in biotechnology and gene therapy.
