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Bacteria and Viruses
Chapter 10
Life Science
Bacteria
More types of bacteria on earth than all
other living things combined
Too small to be seen with the naked eye
All bacteria are single cell
Make up two of the 6 kingdoms (eubacteria
and archaebacteria)
Archaebacteria and eubacteria are the oldest
forms of life on earth
Rigid cell wall allows bacteria to retain their
shape
Some bacteria have flagella to help them
move around
Flagella spin to push a bacterium through
the water or liquid
3 shapes of bacteria
1. Bacilli
2. Cocci
3. Spirilla
Bacilli
Rod shaped
Large surface area which helps take in
nutrients
Large surface area also lets them dry out
easily
Cocci
Spherical
Do not dry out as quickly as bacilli
Spirilla
Long and spiral
Use flagella at both ends to move like a
corkscrew
Prokaryotes
All bacteria are single cell organisms that
do not have a nucleus
Prokaryotes do not have a nucleus or
membrane bound organelles
Able to move, get energy and reproduce
Function as independent organisms
Some may stick together but is still a single
organism
Bacterial reproduction
Binary fission-reproduction in which one
single-cell organism splits into two single
cell organisms
Prokaryotes have no nucleus so their DNA
is not surrounded by a membrane
DNA is in circular loops
Steps of binary fission
1. Cell grows
2. DNA is copied and attached to the cell
membrane (both DNA and DNA copy) but in
separate spots
3. DNA and its copy separate as the cell grows
larger
4. When cell is double its original size it pinches
into and a new cell wall forms separating into
two new cells each with an exact copy of the
parent cell DNA
Endospores
Contains genetic material and proteins and
is covered by a thick, protective coat
Bacteria become inactive and dormant when
they become an endospore
Happens in dry or cold surroundings which
would kill the bacteria since they like warm,
moist places
Many endospores can survive hot, cold, and
very dry places
When conditions improve the endospores
break open and the bacteria becomes active
again
Eubacteria
Most bacteria
Classified by the way they get food
Eubacteria classification
1. Consumer- get food from eating other
organisms
2. Decomposers- feed on dead organisms
3. Parasite- live in or on the body of another
organism
4. Producers- make their own food by using
sunlight’s energy- often green
Cyanobacteria
May have given rise to the first plants on
earth
Producers
Live in water usually
Contain chlorophyll and other pigments
Archaebacteria
3 main types
1. Heat lovers
2. Salt lovers
3. Methane makers
Heat loving bacteria
Archaebacteria
Live in hot springs
Live in ocean vents (thermal vents from
volcano)
Survive temps of more than 2500C
Salt loving archaebacteria
Live in places that are extremely salty and
nothing else can live there
Dead sea
Great salt lake in Utah
Methane making archaebacteria
Give off methane gas
Live in swamps
Live in animal intestines
Causes gas buildup in landfills
Archaebacteria usually live where nothing
else can live
Called extreme bacteria
Cell walls are chemically different from
eubacteria
Bacteria- Good for the Environment
Nitrogen fixation
Recycling
Cleaning up
Nitrogen Fixation
Plants need nitrogen to grow but cannot use
it straight from the air
Nitrogen fixing bacteria take in nitrogen
from the air and change it into a form that
plants can use
This is called nitrogen fixation (fixing
atmospheric nitrogen into a usable form of
nitrogen)
Recycling
Decomposer bacteria break down dead plant
and animal matter into usable nutrients
Cleaning up
Bacteria can be used to fight pollution
Bioremediation (using microorganisms to
change harmful chemicals into harmless
ones)
Bioremediation used to clean up hazardous
waste from industries, farms, cities, and oil
spills
Benefits for humans
1.
2.
3.
4.
Food
Medicines
Insulin
Genetic engineering
Food
Lactose – sugar in milk
Lactic acid producing bacteria break down
lactose changing it into lactic acid which
preserves and adds flavor to food
Cheese, yogurt, buttermilk, cottage cheese,
and sour cream are produced by bacteria
Breads, sausages, pickles etc.
Medicines
Antibiotics- medicines used to kill bacteria
and other microorganisms
Many antibiotics are made from bacteria
Insulin
Insulin is used by the body to break down
and use sugar and carbohydrates
Diabetics do not make enough insulin
1970’s scientists discovered how to put
genes into bacteria so that the bacteria
would make the insulin which then could be
separated from the bacteria and given to
diabetics
Genetic Engineering
When scientists change the genes of
bacteria or any other living things
We can not engineer products such as
insecticides, cleansers, and adhesives
Started in 1973
Harmful Bacteria
Called pathogenic bacteria (bacteria that
cause disease)
Get inside a host and take nutrients from the
host
Harm the host and sometimes kill the host
Many bacterial diseases can be treated with
antibiotics
Vaccinate against some bacteria
Pathogenic Bacteria affects plants, animals,
protists, fungi, and other bacteria
Plants can be treated with antibiotics also
Have genetically engineered certain plants
to be resistant to disease-causing bacteria
Viruses
Microscopic particle that gets inside a cell
and often destroys the cell
Common cold (rhinovirus)
Flu
AIDS
Very tiny
Smaller than a bacteria
Change rapidly
Do not know how many types there are due
to the rapid mutations
Contain protein and genetic material
Can’t eat
Can’t grow
Can’t break down food
Can’t use oxygen
Can’t function on its own
Host
Living things that a virus or parasite lives
on or in
Using a host’s cell the virus forces the host
to make more viruses rather than healthy
cells the body needs
Virus can only reproduce only inside a
living cell that serves as a host
Viral groupings
1.
2.
3.
4.
Shape
Type of disease they cause
Life cycle
Kind of genetic material they contain
4 viral shapes
1.
2.
3.
4.
Crystals
Cylinders
Spheres
Spacecrafts
Crystals
Shaped like a crystal
Cylinders
Looks like a corn cob without the corn
Sphere
Looks like a sphere
Spacecraft
Attacks only bacteria
Every virus is made of genetic material in a
shell
The shell is a protein coat that protects the
genetic material as the virus enters the host
cell
Genetic material
Either DNA or RNA
RNA is made of one strand of nucleotides
DNA is made of two strands of nucleotides
2 types of ways of making more viruses
1. Lytic
2. Lysogenic
Lytic Cycle
1. The virus finds and joins itself to a host cell
2. The virus enters the cell or injects the genetic
material into the cell
3. Once the viruses genes are inside they take over
the direction of the host cell and start making
new viruses
4. The new viruses break out of the host cell
(killing the host cell) and each new viruses finds
another cell to infect and the cycle starts over
Lysogenic cycle
The virus does not go directly into the lytic
cycle
The genetic material stays in the host cell
Each new cell gets a copy of the virus
genetic material as the original cell divides
Genes stay inactive for long periods of time
until something triggers them to become
active
Treating a virus
Most viruses do not have a cure
Need to prevent from happening
Childhood vaccinations
Antiviral medications
Wash hands often
Do not touch wild animals
Antiviral medicines
Stop viruses from reproducing
Childhood vaccinations
Gives the immune system a head start in
fighting off viruses
Helps prevent getting a viral infection
What to do when sick
Drink lots of fluids
Plenty of rest
Checkup with doctor