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Ms. Powells 8th Grade Science Class
Disease Unit Ms. Powells 8th Grade Science Class Types of Disease
Causing Organisms
Virus Bacteria (includes Rickettsia) Protozoa (includes
trypanosomes) Fungus Worms Viruses 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 Have ability to multiply when inside
a living cell Virus Vocabulary 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 Ex. Cold sore virus (Herpes) lies dormant in nerve
cells Potential Hosts of Viruses
No organisms are safe from viruses Viruses can attack: Plants,
Animals, Bacteria, Protists, Fungi Viruses are generally very host
specific Ex. A plant virus does not attack people Naming Viruses
Viruses are not living organisms
Scientists name the virus for the disease it causes Ex. Polio
Scientists name the virus for the organism it infects Ex. Tomato
mosaic virus Scientists name the virus after themselves EpsteinBarr
virus( causes mono) Virus Appearance Very small (smaller than a
bacteria -750 nm)
22 to 250 nanometers Shape: round, rod shaped, bricklike,
threadlike, robotlike or bulletlike Structure of a Virus Two basic
parts:
Outer coat that protects the virus 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 Analogy: chocolate covered
cherry Structure of Viruses Parts of a Virus Virus Photos
Rhinovirus (Common Cold) Hepatitis B How Viruses Multiply Once
inside the cell the viruss genetic material takes over the cells
functions The genetic material tells the cell to produce the viruss
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 Are unicellular microorganisms.
Are typically a few micrometres long Are prokaryotes their cells do
not havenuclei Shapes: spherical, rodlike or spiral Bacteria Rod
Shape, Spherical, Spiral Bacteria Two types: archaebacteria ancient
bacteria
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 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: Bulls Eye Rash at Site to Tick Bite
Rickettsia: Rocky Mountain Spotted Fever Rash Rocky Mountain
Spotted Fever Typhus Protozoan Parasites 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 Dinoflagellates Cilliates Sporozoans Amoeba 4
Types of Protozoa - Locomotion
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
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
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
Intestinal parasites - tape worm, pin worm Onchocerciasis/River
Blindness is an infection caused by the parasite Onchocerca
volvulus (worm) Spread by the bite of an infected blackfly.
Lymphatic filariasis African River Blindness - ParsiticWorm
Parasitic Worm: Lymphatic Filariasis Parasitic worm Parasitic Worm:
Liver Fluke