Pathogens – Bacteria & Viruses Protists & Fungi Too

A Pathogen is…  Pathogen = Any disease causing agent. –Examples:  Bacteria: Streptococcus, Staphylococcus  Virus: HIV, Influenza (Swine Flu), The common cold  Protist: Plasmodium (malaria)  Fungi: Ringworm, Athletes Foot

Viruses – Properties of Life Properties of Life Cellular organization ReproductionYes Metabolism Homeostasis AdaptionYes ResponsivenessYes Growth and Development NO

Virus Size

Viruses are SOOO Small!  Too small to see with a regular light microscope  Must use an electron microscope to be seen.

Parts of a Virus  Capsid= “head”…protein that encloses viral genome  Genome= double stranded DNA OR single stranded DNA or RNA

Viral Body Plans  Genetic material is DNA or RNA  Coat is protein Complex virus (bacteriophage) Polyhedral virus Rod-shaped virus head sheath tail fiber

Viruses are Obligate Intracellular Parasites  Obligate like an obligation – can only replicate inside other cells  Must live within a specific host cell – example: cats don’t get chicken pox  Use the host cell for replication, metabolism, etc.

Viruses cause disease  Influenza –Infects the upper respiratory tract  Can also cause cancer –Hepatitis B  liver cancer –Epstein-Barr virus  Burkitt’s lymphoma –Human Papilloma Virus  cervical cancer

HIV, the AIDS virus  Glycoproteins on HIV envelope recognize surface proteins of human white blood cells  RNA virus  Includes the reverse transcriptase enzyme

Defenses against viruses  Skin and mucus membranes  Inflammation (redness, swelling, warmth and pain)  White blood cells  Antibodies- specific proteins that target a specific virus  Interferons- enzymes that prevent the virus from replicating

T4 Bacteriophages on Escherichia coli) bacteria. T4 bacteriophages are parasites of E. coli, a bacteria common in the human gut. The virus attaches itself to the host bacteria cell wall by its tail fibers. The sheath then contracts, injecting the contents of the head (DNA) into the host. The viral DNA makes the bacteria manufacture more copies of the virus. TEM X40,000. Credit: © Dr. George Chapman/Visuals Unlimited

T4 Bacteriophages on Escherichia coli bacteria. T4 bacteriophages are parasites of E. coli, a bacteria common in the human gut. The virus attaches itself to the host bacteria cell wall by its tail fibers. The sheath then contracts, injecting the contents of the head (DNA) into the host. The viral DNA makes the bacteria manufacture more copies of the virus. TEM X60,000. Credit: © Dr. George Chapman/Visuals Unlimited

Bacteria - Prokaryotes  Eubacteria = True Bacteria. –Cell wall contains the carbohydrate peptidoglycan  Archaeabacteria = Ancient Bacteria. –NO peptidoglycan in cell walls. –MORE similar to Eukaryotes!!! (US) –Live in harsh environments

Bacteria are very small

This is a pore in human skin and the yellow spheres are bacteria

Bacteria are very small compar- ed to cells with nuclei

Bacteria compared to a white blood cell that is going to eat it Bacteria

Clean skin has about 20 million bacteria per square inch

Structure  No nucleus  No membrane bound organelles  DNA is circular Plasmids

Bacteria Shapes Page 546

E. coli is a gram-negative, facultatively anaerobic, rod prokaryote undergoing conjugation. One strain has fimbriae. E. coli can cause urinary tract infections, traveler's diarrhea, nosocomial infections, and a variety of skin and wound infections such as scalded skin syndrome, scarlet fever, erysipelas and impetigo. TEM. Credit: © Dr. Dennis Kunkel/Visuals Unlimited Bacterial Reproduction

 Bacterial reproduction Cellular organism copies it’s genetic information then splits into two identical daughter cells

Conjugation en/thumb/0/02/350px- BacterConjugation.png&imgrefurl= conjugation&h=410&w=350&sz=75&hl=en&start=1&tbnid=JeAQL49IMC- LqM:&tbnh=125&tbnw=107&prev=/images%3Fq%3Dconjugation%26gbv%3D2%26hl %3Den Bacterial reproduction Bacterial reproduction

eria.jpg&imgrefurl= hl=en&start=3&tbnid=oCRN34FnS1MmzM:&tbnh=78&tbnw=123&prev=/images%3Fq %3Dgood%2Bbacteria%2Bin%2Bcolon%26gbv%3D2%26hl%3Den Good Bacteria

Good causing bacteria  E. Coli in stomach aids digestion  Benefit soil  Nitrification  Decomposition  Make acetone or butanol  To produce insulin, other chemicals  Clean oil spills  To clean ore  Yogurt, cheese, olives, vinegar, sourdough

Disease causing bacteria  Way 1: metabolize their host (destroy host cells)  Way 2: secrete poison as waste product

TUBERCULOSIS

STREP THROAT

LYME DISEASE

This bacteria can causes toxic shock syndrome (tampon use) and can also cause impetigo and pyoderma and is common in infant day care centers. SEM. Credit: © Dr. Gary Gaugler/Visuals Unlimited Staphylococcus aureus

Archaeabacteria