Bio 22- Exam 2 Study Guide

Bacteriophage

- "T-even" bacteriophage infect Escherichia coli - T-2 and T-4 - Most widely studied bacteriophage - Go through similar stages as animal viruses

Subcutaneous Mycoses

- Acquired through direct implantation of spores into a puncture would in the skin - Caused by saprophytic fungi that live in soil and on vegetation

Systemic Mycoses

- Acquired through inhalation of spores - Infection begins in the lungs and spread to other body tissues and organs - Not contagious animal-to- human or human-to-human

Creutzfeldt-Jakob Disease (CJD)

- Afflicts the central nervous system of humans -Causes gradual degeneration and death -Transmissible by an unknown mechanism - Several animals are victims of similar diseases: • Scrapie: sheep, mink, elk • -Bovine spongiform encephalopathy: cows

Lysogenic cycle

bacteriophage becomes incorporated into the host cell DNA - phage DNA can be incorporated into the bacterial chromosome (called a prophage)

Genome

the full complement of DNA and RNA carried by a cell

Basic structure of a virus

- protein shell (capsid) surrounding nucleic acid core

Cutaneous Mycoses

- Also called Dermatomycoses - Fungi which cause them are dermatophytes; they secrete keratinase, an enzyme, which degrades keratin - Transmitted human-to-human and animal-to-human by direct contact or by contact with infected hairs and epidermal cells (as with barber clippers or shower room floors)

Definitive Host (Plasmodium)

- Anopheles mosquito - Definitive host - because it harbors the sexual reproductive stage of Plasmodium

Cryptococcus neoformans (fungal)

- Associated with bird feces (normal flora in birds); transmitted by the inhalation of dried pigeon droppings

Properties of viruses

- Can have either DNA or RNA but not both - Are not cells - Are obligate intracellular parasites of bacteria, protozoa, fungi, algae, plants, and animals - Have basic structure of protein shell (capsid) surrounding nucleic acid core

Viral Components of Viruses

- Capsid: Shell made of protein surrounds the nucleic acid - Nucleocapsid: capsid and nucleic acid together - Envelope: Not found in all viruses. Usually, a modified piece of the host cell membrane - Spikes: Found on both naked and enveloped viruses. Project from either the nucleocapsid or envelope. Allow viruses to dock with their host cells

Trichophyton, Microsporum, & Epidermophyton (fungal)

- Cause ringworm (Latin: Tinea)

Toxoplasma gondii (Pathogenic)

- Causes Toxoplasmosis: a disease of blood and lymphatic vessels which may be mild, even asymptomatic in normal, healthy adults - Animals and humans acquire the organism by ingestion of undercooked meat and cat feces

General Shapes of Bacteria

- Coccus: (Round) spheres, oval, bean shaped, pointed - Bacillus: (rod-shaped) cylindrical, filamentous, club-shaped - Spirillum/Spirochete/Vibrio: spiral or curved

Prions

- Common feature of spongiform encephalopathies - Distinct protein fibrils deposited in brain tissue of affected animals

(2) Penetration and (3) Uncoating of Animal Viruses

- Endocytosis: entire virus is engulfed by the cell and enclosed in a vacuole or vesicle - Uncoating: enzymes in the vacuole dissolve the envelope and capsid, releasing the virus into the cytoplasm

Bacterial examples

- Escherichia coli (E. coli) - Streptococcus - Staphylococcus - Bacillus anthracis

Intermediate Host (Plasmodium)

- Human - Intermediate host - because it harbors the asexual reproductive stage of Plasmodium

General Characteristics of Fungi

- Kingdom- Fungi - Eukaryotes - Unicellular(yeast) or multicellular (molds) - Cell walls are present: contain chitin - molds reproduce sexually or asexually by spores - Heterotrophs; nutrients are absorbed from environment - No motility structures - Fungal spores are important in fungal identification

Bacteriophage Life Cycle

- Lytic phase or lytic cycle: life cycle of bacteriophage that ends in destruction of the bacterial cell

Plasmodium (Pathogenic)

- Malaria - Signs and symptoms occur in 48 to 72-hour intervals: - Malaise, fatigue, aches, nausea with or without diarrhea - Chills, fever and sweating - Apicomplexan - live in animal hosts & lack locomotor appendages in mature stages - Asexual phase: carried out in the human - Sexual phase: carried out in the mosquito (Genus Anopheles)

Trypanosoma (Pathogenic)

- Movement by flagella - Chagas disease: carried by Triatoma fly (kissing bug) - African trypanosomiasis (African sleeping sickness): carried by Tse Tse fly

Giradia lamblia (Pathogenic)

- Movement by flagella (8) - Causes Giardial enteritis; Signs & symptoms: diarrhea of long duration, abdominal pain, flatulence; greasy, malodorous stools - Acquired from water contaminated with feces

Balantidium coli (Pathogenic)

- Movement is by cilia (hairlike extensions) - Causes Balantidial dysentery - Acquired through ingestion of drinking water contaminated with feces

Trichomonas vaginalis (Pathogenic)

- Movement is by flagella, no encysting stage - Acquired through vagina/urethral discharge; sexual transmission; suggestion of communal bathing & public facilities - In females causes a white to green frothy discharge - Many cases are asymptomatic, and men seldom have symptoms - Women who become infected during pregnancy are predisposed to premature labor and low-birth-weight infants

Entamoeba histolytica (Pathogenic)

- Movement is by pseudopods (cytoplasmic extensions); also used for feeding - Targets the cecum, appendix, colon & rectum - Causes Ameobic Dysentery: bloody, mucus-filled stools - Abdominal pain, diarrhea, fever & weight loss - Humans are primary hosts; infection through food and water contaminated with cysts; fecally contaminated water

Histoplasma capsulatum (fungal)

- Often associated with bids because it uses bird droppings for nutrients. It is not carried by birds.

Bacteriophage (Italicized)

- Often make the bacteria they infect more pathogenic for humans - Discovered in 1915 by Frederick Twort and Felix d'Herelle - Parasitize every known bacterial species

4 species that cause Malaria

- P. falciparum - P. malariae - P. ovale - P. vivax

Pneumocystis jirovecii (fungal)

- Pneumonia in HIV patients

Dimorphism

- Some fungi can grow as either a mold or a yeast - they can exhibit both morphologies - Usually occurs in pathogenic fungi, in which dimorphism is temperature-dependent

Candida albicans (fungal)

- Thrush, vaginitis

Rhizpopus, Mucor, & Aspergillus

- Ubiquitous - Systemic - Opportunistic pathogens which can be very dangerous to immunosuppressed hosts or when massive numbers of spores are present

(4) Synthesis: Replication and Protein Production

- Viral nucleic acid takes control over the host's synthetic and metabolic machinery - RNA viruses replicate in the cytoplasm - DNA viruses replicate in the nucleus

Rhizopus nigricans (fungal)

- black bread mold

General characteristics of Bacteria

-Unicellular Prokaryotes - Cell wall present: Contains Peptidoglycan - Reproduction: Binary Fission - Nutrition: Most heterotrophs, some autotrophs - Motility Structure- Flagella

Asexual portion of the Plasmodium Life Cycle

1. Sporozoites (infective stage) of Plasmodium enters human with bite of infected mosquito 2. Sporozoites are carried by the blood to the liver 3. In the liver, they undergo schizogony and produce thousands of progeny called merozoites 4. Merozoites re-enter bloodstream and infect RBC's 5. In the RBC's they mature to trophozoites and appear as a ring (called ring stage) 6. Ring stage enlarges, divides repeatedly, causing the RBC to eventually burst and release more merozoites 7. Bursting of the RBC's and release of the merozoite waste products is responsible for the chills and fever associated with malaria 8. Most of these merozoites infect new RBC's and the process repeats itself 9. Some are picked up by feeding mosquitos in which they undergo sexual reproduction and infect other humans

General phases in the life cycle of animal viruses

1. adsorption 2. penetration 3. uncoating 4. synthesis 5. assembly 6. release from the host cell

(6) Release of Mature Viruses

enveloped viruses are liberated by budding or exocytosis - nucleocapsid binds to the membrane - a small pouch is formed - pinching off the pouch releases the virus with its envelope - viruses are shed gradually without destruction of the cell

(1) Adsorption

virus encounters a susceptible host and adsorbs specifically to receptor sites on the cell membrane

General Characteristics of Algae

• Unicellular • Eukaryotes • Various shapes • Photoautotrophs (photosynthetic organisms with chloroplasts - green chlorophyll & other pigments) which produce oxygen and carbohydrates • Important in the "balance of nature" and the food chain • Mostly aquatic • Cell walls contain cellulose • Sexual and asexual reproductive forms - Pfiesteria is an example