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"From Bacteria to Plants" Chapter 2
Section1- Viruses
What Is a Virus?
I. Biologists consider viruses to be nonliving because
viruses are not cells. Viruses do not use energy to
grow and develop, or respond to their environment.
They also cannot make food, take in food, or
produce wastes.
II. The only way viruses are like organisms is their ability
to multiply. However, they need a host to be able
to multiply.
III. No organism is safe from viruses.
Naming Viruses
I. Viruses can be named after the disease it causes
(like the polio virus), the organism they infect (like
the tomato mosaic virus), the place where the virus
was found (like the Ebola virus), or the scientist
who first identified the virus (like the Epstein-Barr
virus).
The Shapes and Sizes of Viruses
I. Viruses can be many different shapes and sizes.
However, all viruses are microscopic and are
measured in nanometers (nm). 1 nm= 1 billionth of
a meter.
Structures of Viruses
I. All viruses have 2 basic parts:
A.An outer coat that protects the virus made of
proteins that allow the virus to attach to a cell.
This is specific to cells, meaning that viruses can
only attach to cells that fit their proteins.
B.An inner core made of genetic material, which is the
instruction for making new viruses.
How Viruses Multiply
I. Once inside, a viruses' genetic material takes over the
cell's functions. The genetic material directs the cell
to produce the virus's proteins and genetic material.
These proteins and genetic material are the
assembled into new viruses.
II. Active Viruses- after entering the cell, the virus
immediately starts replicating itself until it explodes
and releases the viruses.
III. Hidden viruses- after entering the cell, it remains
dormant for a period of time, seeming to not affect the
host, until something switches and the virus then acts
like an active virus.
Viruses and the Living World
I. Viruses can cause disease and death in organisms.
II. Today, though, viruses are being used for good in
techniques in medical treatments, like gene therapy.
Vocabulary: virus, host, parasite, bacteriophage
Section 2- Bacteria
The Bacterial Cell
I.
Anton van Leeuwenhoek first discovered bacteria in
the late 1600s because of his hobby, making
microscopes.
II. Bacteria are prokaryotes. Their cells do not have a
nucleus that contains the cell's genetic material.
III. Bacteria have one of three shapes that help scientists
identify them and are determined by the chemical
makeup of the cell wall:
a. spherical
b. rod like
c. spiral shape
IV. The cell of bacteria is made up of:
A. flagellum
B. the cell wall
C.the cell membrane (which consists of:
• the cytoplasm (the region inside the membrane that
contain gel-like material and genetic material)
• ribosomes (chemical factories where proteins are
produced))
Reproduction in Bacteria
I.
Bacteria reproduce by binary fission, which results in
the production of two cells exactly like the parent cell.
Under the right conditions, they can reproduce as
often as once every twenty minutes.
II. Some bacteria have a simple form of sexual
reproduction called conjugation. This process results
in a cell with a new combination of genetic
information.
Survival Needs
I.
All bacteria need certain things to survive:
A. Food- they can be autotrophic (using the sun's
energy or use the energy from chemical substances
in their surroundings) or heterotrophic.
B. Respiration- the process of breaking down food for
energy.
C. Survival Techniques when their surroundings
become less than favorable- like creating
endospores.
Bacteria and the Living World
I. Bacteria are involved in:
A.Fuel- the wastes of ancient archaebacteria help to
create gasoline.
B.Food- helpful bacteria produce foods like cheese,
yogurt, and apple cider. Some can make food spoil
and get humans sick.
C.Environmental Recycling- they decompose chemicals
in dead organisms to make smaller organisms.
D.Environmental Cleanup- bacteria can help clean up
wastes, like oil spills.
E. Health and Medicine- bacteria can help you digest
food, can give you vitamins, make up some
medicines, and compete for space in your body
(preventing harmful bacteria).
Vocabulary: cytoplasm, ribosome, flagellum, binary
fission, asexual reproduction, sexual reproduction,
conjugation, respiration, endospore, decomposer
Section 3- Viruses, Bacteria, and Your Health
How Infectious Diseases Spread
I.
Infectious diseases spread in one of four ways:
a. Through contact with an infected person- both
direct (like hugging and touching) and indirect (like
inhaling the moisture that an infected person
sneezes/coughs into the air).
b. Through contact with a contaminated object.
c. Through contact with an infected animal- through
bites or scratches.
d. Through an environmental source- like eating food
causing food poisoning or in soil.
Common Infectious Diseases
I.
There are thousands of infectious diseases. Many
depend on location, and some are caused by protists
and fungi.
Treating Infectious Diseases
I.
The best cure for an infection is rest, drinking lots of
fluids, and eating well-balanced meals.
II.
There are two kinds of diseases:
A. Viral- there are no cures for these diseases, but
there are OTCs that can make you feel better.
B. Bacterial- can be cured with antibiotics. However,
antibiotics are becoming less effective because
bacteria are becoming resistant to antibiotics.
Preventing Infectious Diseases and Staying Healthy
I.
Getting vaccines help to prevent diseases by making
your body "on alert" for bacteria and viruses.
II.
The best way to stay healthy is to:
a. eat nutritious foods.
b. get plenty of rest.
c. drink plenty of fluids.
d. exercise.
e. wash your hands often.
f. don't share eating/drinking utensils.
g. make sure you have your vaccines.
h. store foods properly.
i. keep kitchen tools/surfaces clean.
j. cook foods well.
III. When you are sick, :
a. get plenty of rest.
b. follow the Dr.'s orders.
c. don't infect others.
Vocabulary: infectious disease, toxin, antibiotic, vaccine