Transcript Disease Unit

Disease Unit
Ms. Powell’s
8th Grade Science Class
Types of Disease Causing Organisms
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Virus
Bacteria (includes Rickettsia)
Protozoa (includes trypanosomes)
Fungus
Worms
Viruses
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A small nonliving particle that invades and
reproduces inside a living cell
Considered nonliving because:
Viruses are not made of cells
 Do not use energy to grow and develop
or to respond to their environment
 Do not make food, take in food or produce waste
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Have ability to multiply when inside a living
cell
Virus Vocabulary
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Host: a living thing that provides a source of
energy for a virus or other organism
 Parasite: organisms that live on or in a host
and cause harm to the host
 Active virus: enters a cell and immediately
begins to multiply
 Hidden virus: the genetic material lies dormant in
a cell for a period of time before becoming active
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Ex. Cold sore virus (Herpes) lies dormant in nerve
cells
Potential Hosts of Viruses
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No organisms are safe from viruses
Viruses can attack:
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Plants, Animals, Bacteria, Protists, Fungi
Viruses are generally very host specific
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Ex. A plant virus does not attack people
Naming Viruses
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Viruses are not living organisms
Scientists name the virus for the disease it causes
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Scientists name the virus for the organism it
infects
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Ex. Polio
Ex. Tomato mosaic virus
Scientists name the virus after themselves
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Epstein–Barr virus ( causes mono)
Virus Appearance
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Very small (smaller than a bacteria -750
nm)
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22 to 250 nanometers
Shape: round, rod shaped, bricklike,
threadlike, robotlike or bulletlike
Structure of a Virus
 Two
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Outer coat that protects the virus
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basic parts:
Made of protein
Protein shape allows virus to lock onto certain
cells
Cell surface and virus coat is like a “lock and key
fit” – makes virus specific to certain cells
Inner core made of genetic material
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Analogy: chocolate covered cherry
Structure of Viruses
Parts of a Virus
Virus Photos
Rhinovirus (Common Cold)
Hepatitis B
How Viruses Multiply
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Once inside the cell the virus’s genetic
material takes over the cell’s functions
The genetic material tells the cell to
produce the virus’s proteins and genetic
material
These proteins and genetic material are
assembled into new viruses that are
released from the cell
How Viruses Multiply
How HIV Invades a Human Cell
Herpes zoster Shingles/Chickenpox
Virus: Smallpox
Polio Virus: Neuromuscular Damage
Bacteria
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Are unicellular microorganisms.
Are typically a few micrometres long
Are prokaryotes – their cells do not have
nuclei
Shapes: spherical, rodlike or spiral
Bacteria
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Rod Shape,
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Spherical,
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Spiral
Bacteria
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Two types:
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archaebacteria – ancient bacteria
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Live in hot springs and other extreme
environments
Eubacteria – live everywhere else
Bacteria (blue and purple rods) and other
microorganisms lurk in a kitchen sponge
Bubonic Plague: Bubos –swollen
gland
Rickettsia
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Rickettsia species are a type of bacteria
Are carried as parasites by many ticks,
fleas, and lice
Cause diseases such as Rocky Mountain
spotted fever, and typhus in humans
Rickettsia: Lyme Disease: “Bull’s
Eye” Rash at Site to Tick Bite
Rickettsia: Rocky Mountain Spotted
Fever Rash
Rocky Mountain Spotted Fever
Typhus
Protozoan Parasites
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Protozoa (in Greek proto = first and zoa =
animals) are single-celled eukaryotes
(organisms whose cells have nuclei)
Commonly show characteristics usually
associated with animals
Most notably mobility and heterotrophy
4 Types of Protozoa
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Dinoflagellates
Cilliates
Sporozoans
Amoeba
4 Types of Protozoa - Locomotion
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Flagellates are cells with one or more whip-like
tail called flagella. (trypanosomes?)
Ciliates –use hair-like cilia to move (malaria)
Amoeba move by means of temporary
projections called pseudopods,
Sporozoans spore-forming, parasites of animals.
Motile structures such as flagella or pseudopods
are absent
Protozoa: Life Cycle of Malaria
Mosquito Transmission of Malaria
Protozoa - Trypanosomes
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Undergo a complex lifecycle which may
include several different morphological
forms
Often transmitted by invertebrates.
African Sleeping Sickness/Tsetse fly
Chagas Disease, Triatome bug
Tsetse Fly
African Sleeping Sickness
Trypanosome and Red Blood Cells
Trypanosomiasis – Parasite Seen in
Blood Sample
Fungal Diseases
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Eukaryotic organisms (nucleus in cell)
Digest their food externally, absorbing
nutrient molecules into their cells.
Related to yeasts, molds, and mushrooms
Ringworm, Athletes foot, Nail fungus
Fungus: Ringworm
Helminths - Parasitic worms
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Intestinal parasites - tape worm, pin worm
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Onchocerciasis/River Blindness is an
infection caused by the parasite
Onchocerca volvulus (worm)
Spread by the bite of an infected blackfly.
Lymphatic filariasis
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African River Blindness ParsiticWorm
Parasitic Worm: Lymphatic Filariasis
Parasitic worm
Parasitic Worm: Liver Fluke