Unit 5 Review
Infectious diseases are caused by infectious agents (bacteria, viruses, fungi, protozoa, helminthes and
prions).
Infectious diseases are transmitted in a variety of ways (through the air, bodily fluids, contaminated
surfaces, contact with the infected, ingesting contaminated food/water, or ingesting a parasite).
Transmission is the way a microbial organism moves from one host to another.
Bacteria are classified by six morphological characteristics (elevation, pigment, texture, optical
properties, margin, and shape) and by reaction to the Gram stain.
Single-celled microorganisms that are often aggregated into colonies or motile by means of flagella,
typically live in soil, water, organic matter, or the bodies of plants and animals, are usually autotrophic,
saprophytic, or parasitic in nutrition, and are noted for their biochemical effects and pathogenicity is
called bacteria.
Fungi are saprophytic and parasitic spore-producing eukaryotic organisms that lack chlorophyll and
include molds, rusts, mildews, smuts, mushrooms, and yeasts.
A helminth is a parasitic worm (tapeworm, liver fluke, ascarid, or leech).
Prions can be described as any of various infectious proteins that are abnormal forms of normal cellular
proteins, that proliferate by inducing the normal protein to convert to the abnormal form, and that in
mammals include pathogenic forms.
Any protist of the phylum or subkingdom Protozoa is a protozoan.
A virus is any of a large group of submicroscopic infective agents that typically contain a protein coat
surrounding an RNA or DNA core of genetic material but no semi-permeable membrane, that are
capable of growth and multiplication only in living cells, and that cause various important diseases in
humans, animals, or plants.
Any of various infectious proteins that are abnormal forms of normal cellular proteins, that proliferate
by inducing the normal protein to convert to the abnormal form, and that in mammals include
pathogenic forms are prions.
Performing lab techniques under sterile conditions to assure that your specimen is not contaminated
and that infectious agents used do not spread is called aseptic technique.
An antibody is an antigen-binding immunoglobulin, produced by B cells, that functions as the effecter in
an immune response.
A cylindrical or rod-shaped bacterium is called bacillum.
A spherical bacterium is called coccus.
A spiral-shaped bacterium is called spirillum.
If you’re immune, you are able to resist a particular disease through preventing development or
counteracting the effects of the disease.
An infection is the state produced by the establishment of an infective agent in or on a suitable host.
If something is contagious then it is communicable by contact.
Virulent means that something is very likely to cause disease.
A branch of biology dealing especially with microscopic forms of life (as bacteria, protozoans, viruses,
and fungi) is called microbiology.
The first person who contracted a disease and then spread it to others is called patient zero.
Gram staining is a method for the differential staining of bacteria that involves fixing the bacterial cells
to a slide and staining with crystal violet and iodine, then washing with alcohol, and counterstaining with
safranin. Results in gram-positive bacteria retaining the purple dye and gram-negative organisms having
it decolorized so that the red counterstain shows up. This process tells us whether a bacterium is Gram
positive or Gram negative, which helps to identify what kind of bacteria it might be.
Steps of Gram Staining
1. FIX. Apply heat to the slide to ensure that bacterial cells are fixed to it.
2. CRYSTAL VIOLET IODINE. Flood slide with crystal violet dye (which penetrates the thick
peptodoglycan layer and the plasma membrane of the bacterial cell.
3. RINSE. Rinse slide with water.
4. IODINE. Flood the slide with iodine (because the iodine ions penetrate the cell wall and bond
with crystal violets which then react to form a large, insoluble crystal violet-iodine complex.)
5. RINSE. Rinse with water.
6. ALCOHOL. Decolorize the slide with alcohol.
7. RINSE. Rinse with water.
8. SAFRANIN DYE. Flood the slide with safranin dye.
Bacteria
alive
unicellular
treated by antibiotics
any environment
Reproduce
Virus
not alive
no cells
vaccines or no cure
specific to cells
mutate
Three ways to identify bacteria are Gram staining, colony isolation, and biochemical tests.
Kocuria Rhizophila is a coccoid-shaped, acid tolerant, gram-positive bacterium that infects mammal
skin, soil, and water.
Kocuria Rosea is a gram-positive bacterium found on mammal skin that is naturally widespread.
Stigmatella Aurantiaca is a rod-shaped, gram-negative bacterium with fruiting bodies that is found on
rotting wood, fungi, and soil.
A motility test determines whether or not an organism has flagella and thus is capable of swimming
away from a stab mark. If the tube looks cloudy, then flagella are present, but if the tube is clear, then
the organism was not able to swim away from the stab mark.
A catalase test tells you if an organism produces the enzyme catalase. If there are bubbles (resulting
from oxygen gas production) at the end of the test, then the organism produces catalase.
An arabinose test determines whether an organism can use the sugar arabinose for a food source. If the
color of the test tube changes from red to yellow, then the arabinose sugar has been used as food.
Antigens are located on the surfaces of pathogens.
In a viral attack, the B-cells target the infectious agent, marking it as an enemy and then T-cells destroy
the infectious agent.
For pathogens to cause disease, they must enter the host body, adhere to specific cells, invade and
colonize tissues, and then inflict damage.
The function of the cardiovascular system is to pump blood throughout the body.
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heart – a muscle that delivers blood to the body
veins – carry deoxygenated blood to the heart
arteries – carry oxygenated blood to the rest of the body
The function of the digestive system is to break down food to get nutrients for the body.
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liver – separates nutrients from waste
esophagus – pathway between mouth and stomach
teeth – physically break down food
The function of the immune system is to fight illnesses and harmful bacteria.
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B-cells – release antibodies
lymphnodes – protects body from foreign cells
spleen – purifies blood and stores blood cells
skin – barrier against outside world
thymus – protection from fatal pathogens
T-cells – attack foreign cells
white blood cells – infection protection
The function of the nervous system is to transmit brain signals throughout the body.
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brain – interprets and stores information and initiates movement of the body
brain stem – controls breathing, digestion, etc. and sends messages from the brain
nerves – get information from the body and environment
spinal cord – motor and sensory functions
The function of the urinary system is to eliminate waste from the body.
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bladder – stores urine
kidney – reabsorb fluid
ureters – force urine into bladder
urethra – urine flows out of body through this
The function of the respiratory system is to help you breathe.
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alveoli – gas exchange
bronchial tubes – transport air to lungs
lungs – take in oxygen and remove carbon dioxide
nasal cavity – passage for air
larynx – allows you to talk, swallow, breathe; holds vocal cords
trachea – sweep fluids and pathogens out of airway
Infectious Agents
Bacteria
Viruses
Fungus
Protozoa
Transmission
Bacterium is spread
through the air or
contaminated surfaces.
Viruses can be spread
through contact with
the infected,
contaminated surfaces,
or ingesting
contaminated water.
Fungi are spread
through the air, contact
with contaminated
surfaces, people, or
animals.
To get a protozoan
infection, you would
have to ingest
something or come into
contact with someone
that is infected.
Reproduction
Treatment
no host
antibiotics
host
no cure
with or without host
anti-fungal drugs
host
specific to infection
Helminthes
Prion
Helminthes infections
are contracted when
you come into contact
with or ingest
something infected.
Prions spread when
contact with infected
human tissues is made.
no host
anti-parasite medicine
No host
no cure