Microbiology week 2 sunday

• i. Fungi
• ii. Protozoa 
• iii. Helminths

• i.  viruses
• ii.  viriods 
• iii. prions

• eukaryotic cells
• (all fungi )reproduce sexualy and nonsexually) 
• nonmotile 
• heterotrophic (use organic compounds a carbon source; they can’t make their own sugars(FOOD); no photosynthesis)

Yeast

decomposing dead & decaying matter important in ecosystems as decomposers 

• hyphae can be coenocytic NO SEPERATION NO CROSS WALL (undivided network of branching tubes) or have SEPTA (cross walls).
• CAN BE MULTI AND UNICELLULAR  ARE ROD SHAPE

• •cellulose, chitin (contains nitrogen - also found in the
• exoskeletons of insects, crayfish, etc.), or a combination of the two.

• Asexual
• Sexual

• Occurs by elongation of hyphae, budding, or asexual spore production
• Only contain one genome
• Budding is one cell copying its genome and seppararing (like yeast)

mitosis (one cell divides to form 2 daughter cells that are identical to one another and to the original parent cell).

• sporangiospores
• conidiospores

producing sexual spores, which form following sexual fusion of gametes (similar to sperm & eggs)

• zygospore
• ascospores
• basidiospores

hyphi

• Imperfect fungi, group not known much about only that they reproduce asexual and are temporary grouping
• untill more info is known

• •Yeast are nonfilamentous and unicellular
• •Molds are filamentous and multicellular

• •Fungi are eukaryotes
• •Fungi are heterotrophs 
• •Can reproduce via asexual and/or sexual reproduction
• •Can cause human diseases
• •Many different types of fungi

• •Humans usually acquire fungal disease from nature; they are not highly contagious.
• •Fungi are a leading cause of nosocomial infections (hospital aquire infections)
• Fungal infections are a major problem in immune suppressed people. 
• Fungal infections are often mistaken for bacterial infections, with fatal consequences.

• •Superficial
• •Cutaneous 
• •Subcutaneous  
• •Systemic (most dangerous) 
• •Opportunistic (most dangerous)

• Pityriasis versicolor--pigmented lesions on torso
• Tinea nigra--gray to black macular lesions often on palms
• Black piedra--dark gritty deposits on hair
• White piedra--soft whitish granules along hair shaft
• All are diagnosed by microscopy and are easily treated by topical preparations

• Microsporum
• Trichophyton 
• Epidermophyton 
• -cause infections of skin and its appendages

• 1.Coccidioides immitis
• 2.  Histoplasma capsulatum 
• 3.Blastomyces dermatitidis 
• 4.Paracoccidioides brasiliensis  (S. America)

•Coccidiodes immitis is considered to be the most virulent of fungal pathogens.

• •Fungal infections that do not normally cause disease in
• healthy people, but do cause disease in people with weakened immune defenses (immunocompromised people).

Local factors such as pH and glucose concentration (under hormonal control) 

• Unicellular eukaryotes.
• Animal-like
• Limited to a moist environment because they lack a cell wall
• Heterotrophs

• 1.fission (one cell divides to form 2 identical daughter cells and budding
• 2.schizogony (multiple fission). 

• 1.conjugation: the fusion of vegetative cells
• 2.fusion of specialized gametes called gametocytes.

• Some have complex life cycles
• Requiring multiple hosts and changing their morphology 
• Plasmodium uses the mosquito as an intermediate host

• active, motile, feeding stage of protozoans; parasitic stage
• that causes the disease in the host

resistant, inactive stage; how diseases are usually transmitted by the fecal-oral route; usually more useful than trophozoites for lab identification

locomotion or motility

• Move by means of pseudopodia or "false feet"
• Temporary extensions of the cell body caused by protein filaments of the cytoskeletonpushing on the cell membrane)
• Feed on algae, bacteria, and other protozoans by phagocytosis.

• Move by means of flagella
• Some can also have pseudopodia
• Many are disease-causing species
• Some are parasites

• Move by means of cilia
• Cilia are short, hairlike projections of cytoplasm composed of pairs of microtubules surrounded by cell membrane.
• Multinucleate organisms
• Macronucleus controls cell functions and asexual reproduction.  
• Micronucleus is also involved with sexual reproduction.

• Basically nonmotile. 
• All have an infectious, sporelike stage (sporozoite) that is often transmitted to new hosts by an insect vector. 
• All are parasitic (obligate parasites - cannot live apart from the host).  
• Some have elaborate life cycles, changing body form (trophozoite, sporozoite, merozoite)
• Life cycle includes schizogony (multiple fission).

• Ameobiasis
• Chaga’s disease
• Malaria
• African sleeping sickness
• Leishmaniasis 
• Taxoplasmosis.

• Flagellated protozoans
• TseTse fly carries
• Stages:
• --Systemic: multiplies in blood
• --Progresses to neurological stage, infects central nervous system   → meningoencephalitis 
• --Loss of consciousness.  Hence, the SLEEP part.

• Anopheles Mosquito 
• ----Plasmodium. falciparum– most virulent and prevalent

(insects) that convey a parasite from host to host

Heterotrophs

• Multicellular 
• Eukaryotes
• Heterotrophs
• Reside in humans, but do not usually replicate there
• Not intracellular
• Most infected individuals carry few, immune system not heavily engaged, level of immunity generated is often poor

Concentration of sensory receptors toward the anterior end

Most are monoecious (Male & Female) both reproductive organs in same animal 

Dioceious (Seperate Sexes)

Flat and round worms

• Flatworms 
• Most are free living 
• Marine and Freshwater 
• Predator, Scavengers, or Parasitic 
• Some have regenerative capabilities

Flatworms = Platyhelminthes

• All parasitic of vertebrates
• Have complex life cycles that include sexual and asexual phases
• They require at least 2 kinds of organisms to complete the cycle
• They reach sexual maturity in a primary or definitive host (always a vertebrate), their larval stages develop or become encysted in an intermediate host (usually an invertebrate).

• Intestinal parasites of vertebrates
• No digestive system like in trematodes & nematodes
• They absorb nutrients through their tegument! 

• Scolex (head) with suckers and/or hooks (for attachment)
• Proglottids (body units - each one has male and female reproductive organs)
• 1.immature proglottids (closest to the scolex)
• 2.mature proglottids (next closest to the scolex)
• 3.gravid proglottids (furthest from the scolex - in these proglottids, the uterus is filled with eggs).

• The gravid proglottids break off and are passed in the definitive host's feces
• Larval forms hatch when the eggs are ingested by the intermediate host
• Larvae then encyst in the intermediate host (called a cysticercus or bladder worm)
• Adult worms usually develop in the definitive host when raw or poorly cooked infected meat is eaten.

cysticercus or bladder worm

Every organ in the body 

toxins and usually causes a severe allergic reaction, which is sometimes fatal.

• Nematodes are everywhere!!!! 
• They are freeliving in soil, fresh & salt water, & are parasitic in plants and animals.
• Dioecious (separate sexes).
• •Possess
• a nonliving cuticle, which is secreted by the epidermis and is resistant to the
• digestive enzymes of the hosts.
• More highly developed than flatworms.
• Adults do not latch onto the host like the tapeworms

roundworms in the small intestine

trematode worm causing debilitating infection

Tapeworm of cattle and pigs

roundworm of pigs causing Trichinosis

• –S. mansoni (intestinal mesenteric veins)
• –S. japonicum (intestinal mesenteric veins) 
• –S. haematobium (urinary bladder veins

cercariae (free swimming larvae)

digestive enzymes and bore into skin

• •½ the eggs can remain: invade intestinal wall, liver, or bladder → hemorrhage
• Unexcreted eggs induce
• cell-mediated delayed type hypersensitvity.  Large granulomas are formed and walled off by fibrous tissue
• Granulomas often obstruct venous blood flow to the liver or bladder.
• Survive for up to 20 years evading attack of localized cellular buildup of immune andinflammatory cells

• (Pork Tapeworm) 
• Humans can be infected with the adults by consuming rare pork containing cysticerci larvae
• Larvae then develop into adults in digestive tract of the human.

• Largest intestinal nematode (round worm) in humans.
• Disease is called ascariasis 
• Eggs can remain viable even in preservative! 
• Females are longer; males are shorter & have a hooked posterior end

Multicellular eukaryotes

• flatworms and roundworms

Eating uncooked meat

• General characteristics
• Life cycle
• Growing virus
• Viral infections
• Other acellular organisms

• Obligate intracellular parasites (can reproduce/replicate only inside a host cell)
• Not cells
• Consist of nucleic acids (DNA or RNA) in a protein coat, called a capsid (no cell membrane)

host cell & direct the host cell's metabolic machinery to make more virus

all cellular organisms

• 1. reproduction
• 2. metabolism
• 3. organized as cells, contain all organic molecules (lipids, enzymes, nucleic acids, carbs)
• 4. evolution & adaptation to changing environments.

• They can evolve
• They contain some macromolecules
• They direct their own reproduction
• However, they are not cells - they do not have cytoplasm, a cell membrane, organelles, ribosomes, or a nucleus. 
• They have DNA or RNA, unlike prokaryotic and eukaryotic cells, which have both.   
• In addition, they lack a metabolism of their own (they cannot produce ATP, etc.) - raw materials and driving force (ATP & reducing power) are supplied by the host cell.

• Size
• Structure
• Host range
• Life cycles

nucleic acid surrounded by a protein capsid

• A complete viral particle (= capsid + nucleic acid + envelope if it is present) 

Nucleic Acid

Capsids

Capsomeres

• Helical 
• Polyhedral 
• Complex

proteins fit together as a spiral to form a rod-shaped structure

• proteins are arranged in equilateral triangles that fit together to form a geodesic dome-shaped structure; some appear almost spherical; you may have seen
• architectural structures that have this shape

combination viruses with a helical portion (tail) attached to a polyhedral portion (head); ex. many bacteriophages; may also have a tail sheath (participates in injecting the viral nucleic acid into the host cell), plate, pins, & tail fibers (help virus attach to host cell).

Naked Viruses

Fusion of the envelope with the host's cell membrane

• Attach to a cell
• Attachment depends on the presence specific receptor sites

Proteins, LPS’s, glycolipids, or glycoproteins.

• a.  Adsorption - the virion attaches itself to a
• specific receptor site on the surface of the host cell.
• b.  Penetration - the viral nucleic acid penetrates the host cell
• c. Uncoating - removing the capsid & envelope
• d.    Viral Synthesis (Latent Period) (also
• called biosynthesis) - more viral components 

integrated into a host cell's chromosome (the integrated viral DNA is called a prophage

Cell division

Embryonated chicken eggs 

fuse, creating giant, multinucleated cells. (Infection that can be seen under the microscope

• HIV
• (Human Immunodeficiency Virus) which causes AIDS (acquired immune deficiency syndrome); infects T cells (type of white blood cell).

enzyme reverse transcriptase to make DNA from its RNA.  This DNA can be integrated into the host cell's chromosome

HIV, helps stop reverse transcription by targeting the enzyme reverse transcriptase

uncontrolled growth of tissue (cells are dividing out of control); most are benign (non-life threatening); some are malignant (they spread or metastasize to surrounding tissues).

malignant tumors that metastasize to surrounding tissues

Most human cancers arise form genetic mutations or cellular damage caused by environmental factors (chemicals - nicotine, pesticides; radiation - UV, X-rays, etc.; diet).  About 15% are attributed to viral infections.

• Human T-cell leukemia (blood cancer),
• Epstein-Barr virus causes Burkitt's lymphoma
• Hepatitis B virus causes hepatocellular carcinoma (liver cancer)
• Human papillomavirus causes skin & cervical cancers.
• Kaposi’s sarcoma – thought to be associated with herpesvirus

• Viroids: circular molecule, dont produce proteins, cause plant disease 
• Prions: Infectious agent composed only of protein, affect CNS, 

eukaryotes that can cause mycoses

unicellular animal-like eukaryotes

are multicellular parasites

are acellular infectious agents