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