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Chapter 6-1
• Classification: grouping things based on similarities of
characteristics; this way it is more organized and easier to study.
• Taxonomy: how living things are classified
• History of classification of living things:
- Early: Aristotle divided animals into 3 groups; those that fly,
those that swim, and those that crawl/walk/run. He also
subdivided the groups.
- Linnaeous classified according to characteristics of organisms.
He also devised a 2-part naming system called Binomial
Nomenclature using the Genus and Species names of an
organism. Ex. Homo sapiens for humans.
Genus: a classification group of closely related organisms;
name written starting with a capital letter, in italics, and in Latin
Species: classification group of very closely related organisms
that can mate and produce fertile offspring; name written in
italics and Latin
- Today: 7 levels of classification: Kingdom, phylum, class,
order, family, genus, and species.
The more levels shared with another organism, the more closely
related they are.
Organisms with similar evolutionary histories are grouped
together.
As you move down the classification system, the number of
organisms in each group decreases, and they become more
closely related.
• Identification of organisms:
- Field Guides: books with illustrations that tell us about
differences between similar-looking organisms
- Taxonomic Keys: series of paired statements describing the
physical traits of different organisms
Chapter 6-2
Scientists base the classification of organisms on :
a. type of cell: prokaryote or eukaryote
b. # of cell: unicellular or multicellular
c. ability to make own food: autotroph or heterotroph
Archaebacteria
• prokaryote
• unicellular
• some autotrophs; some heterotrophs
• tiny
• referred to as “ancient bacteria”
• live on ocean floor, salty water, hot springs, inside you
Eubacteria
• prokaryote
• unicellular
• most autorophs; some heterotrophs
• have different chemical make-up than archaebacteria
Protists
• eukaryotes
• most unicellular; seeweeds are multicellular
• some autotrophs; some heterotrophs
• referred to as “odd & ends” group since some are animal-like, others are plantlike; others are fungus-like
Fungi
• eukaryotes
• multicellular; yeast is unicellular
• heterotrophs that feed on dead/decaying organisms
• found everywhere
Plants
• eukaryotes
• multicellular
• autotrophs
• variety of species
Animals
• eukaryotes
• multicellular
• heterotrophs
• have different adaptations to their surroundings
• live in many environments
Chapter 6-3
Bacteria
• General
- found everywhere
- autorophs or heterotrophs
- unicellular
- prokaryotes
- shapes: spherical, rod-like, spiral; each type has a different
shape
- cell structure: see page 194 (picture)
a. cell wall: determines the shape
b. cell membrane
c. cytoplasm has the genetic materials and ribosomes
d. flagellum for moving; some don’t have and move depending
on the water currents or wind or clothing
• Kingdoms: 2 based on chemical make-up
a. Archaebacteria: can live in extreme environments; produce bad
smell
b. Eubacteria: can live everywhere else; most are useful or harmless
– they help keep the Earth’s oxygen level at 20%
• Reproduction
In order to reproduce, bacteria need plenty of food, the right
temperature, and other suitable conditions. They can reproduce every
20 minutes. Fortunately, growing conditions are not always ideal.
a. Asexual reproduction (binary fission): cell divides into 2 identical
cells; 1 parent needed; offspring are identical to parent
b. Sexual reproduction (conjugation): 2 parents exchange their
genetic materials; no new bacteria formed but they are genetically
different
• Survival needs
a. food: they are either autotrophs using the sun or ocean chemicals
or heterotrophs that eat autotrophs or other heterotrophs (milk,
meat, decaying leaves)
b. respiration: breaking down food using oxygen to get energy ; a
few can be poisoned by oxygen so they do respiration in the
absence of oxygen
c. when conditions become not favorable, they form endospores small, round resting cells – until conditions are favorable again
• Bacteria and the Living World
Most are harmless or useful. Some cause problems.
a. Fuel: archaebacteria produce methane gas (a major component of
natural gas) during respiration without oxygen.
b. Food: some are used to make certain foods such as pickles,
vinegar, buttermilk, sour cream, yogurt, cheese; others cause food
to spoil (food tastes and smells bad) and make you sick. To slow
down spoilage, we can heat, refrigerate, dry, salt, or smoke the
food.
c. Environmental Recycling: heterotrophic eubacteria are
decomposers in the soil; they break down large chemicals in dead
organisms into small chemicals returning important nutrients to the
environment. Also these bacteria help plants get nitrogen by
changing the nitrogen in the air into chemicals in the soil.
d. Environmental Cleanup: bacteria clean up oil spills by changing
dangerous chemicals into harmless ones.
e. Health: some cause infectious diseases by direct contact, by
indirect contact, through open wounds, through animal bites, and
through air/food/water. They produce a poison, called toxin.
These diseases can be treated with antibiotics. But other bacteria
are good for the digestive system: help you digest, make vitamins,
and prevent harmful bacteria from attaching to your intestines
Chapter 6-4
Viruses
• Virus: a small, non-living particle that can reproduce inside a living
thing; viruses have no cells and therefore are not living.
• The virus invading a cell is referred to as the parasite; the cell which is
invaded is called the host.
• Each virus can infect few types of cells and in a few specific species.
• Viruses are named after
- the disease they cause
- the organism they infect
- the place they were found in
- people
• Viruses can be round, rod-like, brick-like, thread-like, bullet-like,
robot-like (ex. of the robot-like is Bacteriophage, meaning bacteriaeater, are the viruses that attack bacteria).
• Viruses are very small; scientists use nanometers to measure them.
• Structure of viruses:
- outer protein coat needed for protection and during cell
invasion; each virus has a unique protein; the shape of the
protein determines the type of cell or part of the organism that
is invaded
- inner core of genetic material that contains the instructions for
making new viruses
• How viruses multiply
- virus attaches to the cell
- virus enters the cell
- the genetic material of the virus takes over and directs the cell
to make new viruses
• Active virus: the virus immediately goes into action; when the cell is
full of viruses, it bursts and releases them
Hidden virus: after the virus enters the cell, its genetic material
becomes part of the cell’s DNA; it stays inactive for a while; then it
makes new viruses; the cell bursts to release the new ones when full
• Two factors that may activate the cold sore virus are sunlight and
stress.
• Viral Diseases:
- common cold, influenza (flu), chicken pox, AIDS
- are spread by direct/indirect contact, through food/water/air,
and by animal bites
- no medications to cure them; however we have OTC
medications to treat symptoms; the best thing to do is bed rest
and lots of fluids
- important: prevention is by vaccines(substances that produce
chemicals to destroy viruses and bacteria); they are made of the
same virus/bacterium but dead or weakened or made from their
toxins; they will not cause the disease