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TAKS Review
Bacteria and Viruses
Characteristics of Bacteria
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•
•
•
•
Unicellular
Prokaryotic
Can be autotrophs or heterotrophs
Can be aerobic or anaerobic
Can be motile or non-motile
– For motility bacteria have cilia or flagella
Bacterial growth and
reproduction
• Asexual reproduction is called binary
fission
• Sexual reproduction is called
conjugation
• Some bacteria also form endospores
to survive harsh conditions and then
germinate when conditions become
favorable
Bacteria can be beneficial
• Make essential soil mineral elements
available to the plant: nitrogen fixation
• Decompose organic matter and
improve soil nutrient content
• Bacteria can aid in producing drugs,
hormones, or antibodies.
• Bacteria can even help to break down oil to
make clean-up after an oil spill easier
Bacteria can be beneficial
• Bacteria help in the production of fuel
– Some bacteria decompose compost, garbage
and sewage and help make methane. Methane
is a valuable natural gas. It is used widely as a
fuel.
– Some bacteria are now being engineered to
produce various types of fuel including
gasoline, biodiesel and ethanol.
Bacteria can be beneficial
• Some bacteria aid in food production.
Examples are cheese, buttermilk, yogurt,
sour cream and high fructose corn syrup.
• Bacteria and humans form a symbiosis with
each other. Bacteria found in human
intestines help with digestion and also
produce vitamins. In exchange, they soak
up a little extra food for themselves.
Examples of good bacteria
• We pretty much depend on Escherichia coli
in our intestines to provide us with Vitamin
K and B Complex vitamins.
• Lactobacillus bulgaricus found in cheese
and yogurt.
– Aids in the digestion of lactose by producing
the enzyme lactase.
– Boosts the immune system
Pathogenic (harmful) bacteria cause
disease by destroying cells or by
producing toxins that stop the cell from
doing its job
• Staphylococcus aureus-food poisoning
when toxins are ingested
• Streptococcus pyogenes-causes strep
throat—red spots on your throat are red
blood cells the bacteria have destroyed
• Clostridium botulinum-produces toxins that
cause paralysis for 4-6 months (botox
injections are made of these toxins!!!)
Controlling Bacterial Growth
• Pasteurization is used to
remove bacteria from food
• Antiseptics can kill bacteria
on tissues
• Antibiotics are used to kill
bacteria that have entered the
body
• Vaccines can prevent
bacterial infections by
stimulating the immune
system
Practice Question
H. pylori bacteria are known to cause stomach
ulcers, which are sores in the lining of the
stomach. The sores are vulnerable to damage by
stomach acids. A doctor may treat ulcers by
prescribing an antibiotic, which will
A. neutralize stomach acids
B. stop formation of stomach acids
C. kill the H. pylori bacteria
D. cover sores in the stomach lining
C
Practice Question
Streptococcus infection in a person’s throat
can cause pain and fever. Streptococcus can be
controlled by antibiotics. Streptococcus is a —
F virus
G bacterium
G
H protozoan
J fungus
Practice Question
Which of these conditions is caused by
bacteria?
F AIDS
G Seasonal allergies
H Dental cavities
J Colds
H
Practice Question
Many species of bacteria can be found in the
human mouth. Which of these explains the
great variety of bacteria in the mouth?
F Large volumes of air cause bacteria to change form.
G Salivary glands cause mutations in bacterial
populations.
H The presence of nutrients makes the mouth a
favorable habitat.
J Calcium in the teeth provides a suitable pH
environment.
H
Practice Question
4. Some bacteria benefit mammals by helping
with —
F growth
G
G digestion
H defense
J respiration
Practice Question
Which of the following
conclusions is supported by the
information to the right?
F Antibiotics have intensified the symptoms of M.
tuberculosis infections.
G M. tuberculosis is becoming extinct because of antibiotics.
H Antibiotics have caused M. tuberculosis to reproduce at a
faster rate.
J M. tuberculosis has developed resistance to antibiotics.
J
Practice Question
According to the information in the box, J
which of these best describes the
relationship between rhizobia and bean
plants?
F Parasitism
G Opportunism
H Commensalism
J Mutualism
Practice Question
Lactose is a naturally occurring sugar found in milk.
Some dairy products, such as yogurt, may contain
live bacteria. These products are useful to people
who lack the ability to digest lactose. What does
this information demonstrate?
A Bacteria raise the acidity of processed foods.
D
B Some bacteria interfere with digestion.
C Bacteria can prevent insulin production.
D Some bacteria are beneficial to human health.
NOT classified because
THEY ARE NOT ALIVE
Classified into the Kingdom
Eubacteria or Archeabacteria
Viruses vs. Bacteria
Non-living parasite
Living
Cannot reproduce on their
own (uses a host cell)
Can reproduce sexually or
asexually
Contain DNA or RNA inside Contain circular DNA inside
a protective coating (capsid) a cell membrane and cell
wall
Always pathogenic
Can be helpful or
pathogenic
A Virus is:
• A non-living parasite
• Made of nucleic acids, proteins, and
sometimes lipids
• Highly specific to the types of cells they
infect (bacteriophages are viruses that infect
bacteria)
• Able to evolve
What a virus does
A non-living, disease causing parasite that
invades the cell.
It turns the cell into a virus making factory
until it no longer needs the cell.
It then destroys the cell releasing new viruses
to continue the cycle.
Viral Reproduction
http://www.tvdsb.on.ca/westmin/science/sbi3a1/Bacvirus/Virusrep.htm
A virus is NOT:
• Alive
• Capable of reproducing on its own
• Capable of growing and developing during
its ‘life’ cycle
Common Viral Diseases
• Rhinoviruses cause the common cold
• HPV (Human papillomavirus) can cause
cervical cancer in women
• Herpes simplex viruses cause mouth and/or
genital sores, lesions, and ulcers.
• Influenza viruses cause the flu
• HIV (Human Immunodeficiency Virus) causes
AIDS and weakens the immune system
Retroviruses
• Made of RNA
• Inject their RNA into
the host cell
• Host cell makes it into DNA
• Viral DNA joins the host DNA
• Viral DNA pirates the cell and forces the
cell to make new viral RNA and new
viruses
Controlling Viruses
• Antibiotics DO NOT work on viruses.
• Most human viral infections can be fought
off by the immune system—boost the
immune system with lots of water and rest.
• Vaccines are preventative!!!
Controlling Viruses
• Vaccines will NOT cure you if you are
already sick.
• Vaccines stimulate the immune system to
create antibodies that recognize a certain
virus.
• These antibodies patrol your body and if
they recognize that virus…they call in
reinforcements and your immune system
goes to battle!
Practice Question
Viruses differ from bacteria in that all virusesF cause insect-borne diseases
G can be destroyed by antibiotics
J
H have rigid cell walls
J must be reproduced in living cells
Practice Question
J
Which of these is a benefit of knowing whether a person
with a respiratory infection has an elevated level of
this protein in the blood?
F A set of aerobic exercises can be recommended.
G A diet of essential nutrients can be recommended.
H A decision can be made about whether to take an xray.
J A decision can be made about whether to use
Practice Question
Most viruses infect a specific kind of cell.
Which of the following are infected by the
human immunodeficiency virus (HIV)?
F Helper T cells
G Liver cells
F
H GABA-receptor cells
J Red blood cells
Practice Question
Viruses can be
transmitted in a
variety of ways. The
virus that causes
SARS (severe acute
respiratory syndrome)
can be transmitted
when an infected
person coughs or
sneezes. This virus is
transmitted in a
manner most similar
to the transmission of
—
F smallpox
G AIDS
H West Nile
virus
J influenza
J
Practice Question
Which of the following explains why antibiotics can
treat flu-like symptoms caused by bacteria but are
ineffective against flu?
A Flu is a response to an antigen.
B Antibiotics require time to work.
C Antibiotics strengthen antibodies.
D Flu is caused by a virus.
D
Practice Question
Enzymes allow viruses to insert their genetic
material into the host cell’s DNA. The virus
benefits from this action by —
A acquiring the traits of the host cell
B causing the host cell to produce viruses
C introducing random deadly mutations into
the host cell
D turning the host cell into a virus
B
Practice Question
Information About Sendai Virus
• Some infants and children are infected with human parainfluenza
virus type 1, also known as HPIV-1.
• A vaccine against HPIV-1 is made of a low dose of Sendai virus.
• Sendai virus has a similar structure to HPIV-1.
• Sendai virus makes mice sick but does not make humans sick.
Why is Sendai virus used as a vaccine against HPIV-1?
D
A It alters the protein coat of HPIV-1.
B It makes cells chemically unrecognizable to HPIV-1.
C It forms a protective barrier against HPIV-1.
D It triggers the production of antibodies that fight HPIV1.
Practice Question
Scientists are designing new medicines to fight
infectious diseases caused by viruses. One of the
most effective ways these medicines could limit
the spread of the virus within the body would be to
A. prevent viruses from dividing
C
B. burst cells infected with viruses
C. stop viruses from attaching to cells
D. make it easier for viruses to leave cells
Practice Question
Which of the following is found in both
cells
and viruses?
A Silica
B
B Genetic material
C Digestive cavity
D Flagella