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.