Microbiology Exam Three Study Guide What existed pre-eukaryotes? -only archaea & bacteria present in oceans -mostly anaerobes due to little oxygen in atmosphere -cyanobacteria could do oxygenic photosynthesis -living in oceans, so cells had an isotonic environment (no cell wall) -allowed cells tDon't forget about the age old question of (How much did we produce?
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o be predatory, could phagocytize organisms What is the history of eukaryotes? -archaea cell, to begin with (anaerobe, no cell wall) -rickettsia (aerobe) may have been phagocytized by archaea cell, but is not broken down; lives in archaea cell -allowed archaea cell to use oxygen & rickettsia gets to live -rickettsia functioned as endosymbiont: helping archaea live & vice versa -after binary fission, rickettsia is passed down to each cell -rickettsia becomes "enslaved" to archaea cell & gives up its genes -modern-day mitochondria are thought to have come from these rickettsia, can generate ATP -could differentiate into protozoa of protista domain, OR could phagocytize cyanobacteria, which become chloroplasts, & the cell will become an algae of protista domain How are modern-day mitochondria similar to the prokaryotic cells that were phagocytized by archaea? -outer membrane have proteins just like a G- bacteria such as Rickettsia -have single, circular chromosome -have 70S ribosomes -divide independently of cell, by binary fission How are modern-day chloroplasts similar to the prokaryotic cells that were phagocytized by archaea? -outer membrane have proteins just like a G- bacteria such as Rickettsia -have single, circular chromosome -have 70S ribosomes -divide independently of cell, by binary fission What are protozoa? -may have undulipodia -single-cellular, no chloroplast, no cell wall -exhibit polymorphism (exist in multiple life forms): can be in cyst form (resting form, will be transmitted) or trophozoite (active, feeding, motile form) -usually aerobic (can do cell respiration) -are chemoheterotrophs -classified by their means of movement (flagella, cilia, etc) -found in soil/water-are parasites (use living/ organisms as nutrient source) -sporozoa cause 50% of deaths before age of 5 What are protozoa & algae (under the protista kingdom)? -protozoa: unicellular, may have undulipodia, no chloroplasts or cell walls -algae: unicellular/multicellular, may have undulipodia, have chloroplasts (for photosynthesis), have cell wall (made of cellulose) What are fungi (under the protista kingdom)? -are chemoheterotrophs -molds: multicellular, cell wall (made of chitin), generate fruiting bodies (growth on surface) -yeast: unicellular, cell wall (made of chitin) What is amoebic dysentery? -aka bloody diarrhea -caused by entamoeba histolytica (cuts tissue open) -worldwide disease - 50 million cases a year 1) food/water borne, contains cysts of the microbe, enters host 2) once in the large intestine, cyst turns into trophozoite 3) trophozoite pops holes in epithelial lining of large intestine, causing ulcers/ blood entering diarrhea 4) when trophozoite enters bloodstream, it can travel to other organs & cause abscesses -can be asymptomatic for some people What is giardia? -food/water borne (contaminated w/ feces from animals), found in 97% of surface water in lakes, rivers, etc -caused by giardia lamblia: has 2 nuclei, no mitochondria, & 2 adhesive disks to attach themselves onto things -beavers can be reservoirs in nature, will contaminate water w/ feces 1) person ingests cyst w/ food/water, travels to small intestine where it turns into a trophozoite 2) suctions onto villi of intestine, which flattens the villi (causing malabsorption of water & nutrients) 3) causes severe diarrhea & cramping for several weeks 4) eventually the trophozoites become cysts again & shed into the feces to find a new host once out of the body -for the microbe, diarrhea & coughing is beneficial b/c they are more likely to be spread to a new host -can be killed by boiling water before consuming it, using iodine pills, or ozoneWhat is cryptosporidium? -emerging disease (found after 1970's) -leading cause of diarrhea by protozoa -infects mammals, birds, reptiles (transferred via fecal -> oral route) 1) first an oocyst is ingested, which opens up to release a sporozoite in the intestine (looks like a worm) 2) sporozoite infects an intestinal cell, replicates, & changes into a merozoite as replication occurs 3) merozoites rupture intestinal cell & infect new cells (cycle repeats) 4) some merozoites turn back into oocysts & are shed into the feces -causes vomiting, cramps, diarrhea, inflamed gastrointestinal tract for weeks -we can normally fight this off if we're healthy, BUT if we're immunocompromised, it will act as an opportunistic disease & be chronic What is malaria? -re-emerging disease: b/c the microbe showed resistance to DDT -caused by plasmodium falciparum (most common type) -infects humans, animals as well, usually in warmer climates -carried in an anopheles mosquito as a vector, or can be transmitted in a blood transfusion, or from mother to fetus 1) female mosquito infected w/ malaria will bite a human & release saliva carrying to sporozoite 2) sporozoite travels to liver to infect a liver cell, replicates, then changes into merozoites, which are released into the bloodstream 3) merozoites enter RBC's, & turn into trophozoites to feed on the hemoglobin (looks like 2 rings inside RBC) 4) changing back into a merozoite, burst out of the RBC after 2 days & infect new RBC's to feed again (this causes a cyclical, reoccurring fever) 5) sometimes the initial trophozoites can turn into gametocytes, which a new mosquito can suck up (will become sporozoites that can infect a new host) -causes severe anemia & buildup of waste (damaged RBC's never go to spleen & can plug vessels, causing brain damage from lack of oxygen/blood flow) -symptoms: cycle of fever, anemia, enlarged liver/spleen, brain damage, heart attack -therapy thru chloroquine drugs -prevention: mosquito nets What is plasmodium vivax? -species of anopheles mosquitos that cause malaria -more common/widespread, historically (can withstand large temperature range) -was mostly eradicated (killed-off) w/ DDT -can emerge from liver cells in stages, causing relapses of symptoms (can last 1-30 years) -you're more likely to survive b/c of it's stage-like cycle (it's not destroying many RBC's at once)-95% of Africans have a mutation (called Duffy Negative) which prevents merozoite from infecting RBC's What is plasmodium falciparum? -species of anopheles mosquitos that cause malaria -not as widespread, but more deadly recently -no relapses, all liver cells burst w/ merozoites @ same time, so more RBC's are damaged, meaning very low oxygen to brain -carriers of sickle-cell disease are protected -cause 90% of malaria deaths -an HIV infection increases chance of death by malaria What are fungi? -no undulipodia; unicellular (yeast) or multicellular (mold) -develop from spores; cell wall made of chitin -are chemoheterotrophs, releasing exoenzymes to get nutrients from their environent -molds like growing in cool temperatures, but when their spores are airborne & enter a warm place, they can turn into yeast cells (and vice versa) What is yeast? -single-celled, grow in colonies (white/creamy, shiny) -can live in our biofilms -can carry plasmids (used for genetic engineering) -kingdom animalia may have come from yeast -replicate using mitosis, then budding -use fermentation -can cause spoilage & disease What is a yeast infection? -caused by candida albicans -in our normal body flora in mouth, genitals, etc. & don't cause infection b/c other microbes keep it in check -as an opportunistic disease, only infects if you're immunocompromised, OR if you take antibiotics that kill your good bacteria, OR if you have high blood sugar -virulence factors: have adhesins (help them stick to surfaces), in their hyphal form (as mold) they can cause blood clots/be life threatening -thrush: infection in mouth/throat, common in babies -vaginal yeast infection: causes inflammation, discharge -cutaneous candidiasis: yeast infection on moist skin, or burn victims -accounts for 70% of nosocomial (occurring in hospitals) fungal infections -use Amphotericin B as treatment What is a mycoses? -a fungal infection (from yeast or mold)What is mold? -multicellular, consists of hyphae (long filaments) which clump together to form a mycelium (normally grows beneath surfaces, w/ fruiting bodies showing up above the surface) -fruiting bodies on surface hyphae carry the spores -often causes spoilage, used primarily for antibiotics How does a mold mycoses work? 1) could dig up ground/animal feces, which makes the spores airborne & you inhale them 2) once inhaled, can cause lung damage (symptoms are cough, ache, fever), but you can usually fight it off 3) if you're immunocompromised, the infection can cause bone/brain problems, can be deadly -treat with Amphotericin B What is a ringworm infection? -caused by tinea or dermatophyte -is mold that grows on skin, hair, nails (produce exoenzyme keratinase that digests the keratin on these surfaces) -you come into contact w/ fomites thru pedi/manicure, direct contact -tinea corporis: ringworm on body -tinea barbae: ringworm on beard/chin -tinea capitis: ringworm on scalp/hair What are viruses? -discovered in late 1898, means "poison" -most abundant "agent" on earth -all cells can be attacked by viruses (even viruses can be attacked by other viruses) -non-cellular, so technically not alive: cannot maintain themselves, no cell membrane, no organelles -have a genome with DNA or RNA (usually RNA), but cannot do transcription or translation -evolve faster than anything else on the planet -started from transposons? genetic material doesn't match any modern cells -are always intracellular parasites (cannot live outside of host) What is the core of a virus? -innermost layer that holds DNA/RNA & some enzymes -DNA or RNA can be single or double stranded -bacteriophages can have any combo (double DNA & single RNA, single DNA & double RNA, etc)What is the capsid of a virus? -protein coat surrounding core for protection -may have spikes on it that help the virus attach to/penetrate a specific cell -made of small subunits called capsomeres -closed shell capsid: capsomeres are arranged into a shape that enclose genome completely (very geometric-looking) -helical capsid: capsomeres create tube/cylinder stick with the genome inside -complex virus: mixed shape, like a bacteriophage What is the envelope of a virus? -exists on viruses that infect animal cells -is a cell membrane (phospholipid bilayer) that forms from the host cell's membrane when the virus leaves a cell (helps it enter new cells since it looks so similar/disguised) -can also have spikes (help w/ attachment, virulence factor) -the spikes match receptors on host cell, which makes host cell take in the virus, thinking it's harmless -if your cells don't have the correct receptors, virus can't attach & can't infect you -can have hemagglutinin or neuraminidase spikes -if NO envelope, virus is called a naked virus What are hemagglutinin spikes? -bind to Sialic Acid receptors on the respiratory cells in a host & allow the virus to enter the cell What are neuraminidase spikes? -after viral genome replicates when it's in a host cell, the virus pushes onto the host cell's membrane, wrapping itself -these spikes pinch off the membrane so the "bud" can free itself from the host cell & go infect a new cell -Tamiflu inhibits neuraminidase spikes What enzymes are in viruses? -lysozyme: for bacteriophages; enables them to break down cell wall & shoot their genome thru host cell -reverse trascriptase: can turn single-strand RNA into double-strand DNA -integrase: helps "integrate" viral DNA into our (host) DNA (called lysogenization) -protease: cuts viral proteins into individual proteins What are viruses sensitive to? -anything that breaks membranes can break the envelope of a virus (soap) -anything that can denature proteins can break the capsid (high temperatures) -anything that damages nucleic acids will break the core (such as radiation) -antiviral drugs can disrupt replicationWhat is meant by the range of a virus? -the range of organisms that a virus can infect What is meant by the specificity of a virus? -what specific cells can the virus infect (such as nerve cells, intestinal cells, etc) What is adsorption? -virus' spikes binding to receptors on the host cell What is penetration? -the virus enters the host cell -bacteriophages release lysozyme so they can penetrate & release their genome into the cell -for viruses w/ envelopes: fusion occurs (plasma membrane of virus fuses w/ membrane of host cell; capsid w/ genome enter the cell) -for viruses w/ capsid: endocytosis occurs (host cell engulfs virus into a vesicle, once inside the virus sheds the vesicle) What is uncoating? -the virus uncoats the genome from the capsid (either host cell digests capsid or the virus will do it itself) What is synthesis? -make new viral parts (RNA, spikes, capsid, etc) What is synthesis like for DNA viruses? 1) viral DNA enters host cell nucleus, opens up, transcription occurs w/ RNA Polymerase; makes viral mRNA 2) viral mRNA goes thru ribosomes, translates into the creation of spikes, capsid, enzymes, capsomeres 3) viral DNA is also unzipped by helicase 4) DNA Polymerase 3 adds nucleotides & replicates the viral DNA 5) some of the viral DNA can be integrated into our own DNA (lysogenization) causing life-long infection 6) new viruses are created -if you become immunosuppressed, virus can wake-up & cause new symptoms -Acyclovir acts as a competitive inhibitor for DNA Polymerase 3 (looks like a nitrogenous base); can stop production of viral DNA (good for Herpes virus) What is synthesis like for RNA viruses? 1) viral RNA (single-stranded, positive) is inside host cell 2) since it looks like mRNA, goes thru ribosomes to make the proteins it codes for (makes capsomeres, spikes, & Viral RNA Polymerase enzyme) 3) Viral RNA Polymerase makes the oppositve strand of mRNA (negative, instead of positive) w/ complementary nucleotides 4) that opposite strand is now a template to make new (positive) strands that are the same as the original strand -Viral RNA Polymerase makes many mistakes, which causes high mutation rate, making the virus harder to treat What is synthesis like for Retroviruses? 1) single-stranded viral RNA (two copies of it) is inside host cell 2) Reverse Transcriptase (from the virus) takes the viral RNA & transcribes it into a single strand of DNA 3) strand of DNA is read to make a double-strand of DNA (Reverse Transcriptase has the POOREST proof-reading, so mutations occur every 24 hours) 4) Integrase will take the DNA & lysogenize it into the host cell's DNA (this means it becomes a life-long infection) 5) now our RNA Polymerase can transcribe/translate the viral DNA that has been lysogenized into our own DNA, & will create new viruses -Protease snips apart proteins -AZT will competitively inhibit Reverse Transcriptase; mimics nucleotides (however, not selective, so also affects host DNA & can cause Aplastic Anemia) What is maturation/assembly? -the newly created virus parts self-assemble into new viruses What is release? -virus leaves the host cell, two methods to this: 1) Budding: capsid & spikes bind to the host cell membrane, genome of the virus pushes into that & folds the membrane around itself, & buds off the host cell -only enveloped viruses do budding -host cell will not be destroyed immediately 2) Lysis: naked/complex virus bursts host cell open, host cell dies immediately What is a lytic infection? -virus rapidly replicates & spreads, but body/immune system takes over quickly -ex: cold, polio, flu What is a latent/persistent infection? -some of viral DNA incorporated into host cell DNA (now life-long infection) -virus can remain dormant/inactive; but periodically the virus replicates, spreads, becomes contagious, then can go back to being dormant -ex: herpes viruses What is a chronic/persistant infection? -small level of virus is produced gradually & consistently (can even have no symptoms) -can last for months or years until enough cells have been damaged, which shows symptoms of disease -ex: hepatitis B, HIVHow do you cultivate viruses? -need appropriate cells for them to infect -can create cell (tissue) cultures: cultured cells grow in sheets, add virus & observe which cells are infected -can use bird embryos: incubating an egg w/ a virus (acts as a clean environment) -live animal inoculation when needed How are viruses classified? -by their genome (double strand or single) What are DNA viruses? -spread by direct contact (skin, mucous membranes, body secretions) -can lysogenize host cell (incorporate their DNA into ours) -can be latent infections (infection becomes more severe w/ age or being immunocompromised) What is HSV1? -a DNA virus - herpes -causes lesions on mouth, lips, throat usually -contact w/ virus usually happens in early childhood, thru active lesions on someone or even someone with no symptoms, by saliva, skin secretions -will travel from skin to cell body of sensory neurons & will become latent (dormant) - can be reactivated by stress, fever, UV radiation, hormones -when reactivated, the virus travels back onto nerve & goes to skin to cause lesions or itching (outbreaks can decline as time goes by) What is HSV2? -a DNA virus - herpes -causes infection/lesions on genitals usually -contact w/ virus thru sexual/intimate contact -occurs in teen/early-adult years -contact w/ virus thru active lesions on someone or even someone with no symptoms, by saliva, skin secretions, condoms not 100% effective -will travel from skin to cell body of sensory neurons & will become latent (dormant) - can be reactivated by stress, fever, UV radiation, hormones -when reactivated, the virus travels back onto nerve & goes to skin to cause lesions or itching (outbreaks can decline as time goes by) -treated by Acyclovir, slows virus replication What is chickenpox (aka Varicella Zoster)? -DNA virus - herpes -can be transmitted via respiratory droplets or contact w/ skin that has shed virus -replicates in skin cells & appears as small lesions, then can travel up nerves & become latent in cell body of sensory neuron-when reactivated, appears as shingles, which is only visible in dermatome areas (belt-like strip on skin) -more common in older patients due to weak immunity -treated by Acyclovir, slows virus replication -a live, attenuated (weakened) vaccine for chickenpox/shingles was 85% effective -Necrotic Strep: normally lives on skin, but if it enters a chickenpox lesion it can destroy tissue quickly (may need amputation since it spreads so fast) What is Epstein-Barr (Mono) virus? -DNA virus - herpes -causes mononucleosis -is ubiquitous: affects nearly everyone -lysogenizes B Lymphocytes/Cells -transmission via direct oral contact or saliva ("kissing virus") -if infected when young, you show mild symptoms; if infected as teen/adult, have more risk of lysogenization & chronic infectious mononucleosis -Infectious Mononucleosis appears as sore throat, fever, swollen lymph nodes, weakness -can become latent in B Cells, when reactivated you may show no symptoms & infect others easily What is Human Papillomavirus? -DNA virus -usually sexually transmitted or thru non-living fomites -when in contact w/ epithelial cells on skin surfaces, can replicate & appear as warts, which will be contagious since the skin sheds off them -when in contact w/ mucous membranes (thru oral, anal, vaginal sex), can cause genital warts/cancer -the virus will inactivate tumor repressor gene that helps us prevent cancer...so we end up getting cervical cancer, head/neck cancer, anal cancer, throat cancer -Pap smear can show abnormal cervical cells that show the cancer -most humans will normally eliminate HPV before it gets bad -Gardasil 9 is used to treat: as a yeast that has a capsid around it (holds no genome though, but instead holds 9 HPV viruses - 7 for cancer, 2 for warts), it appears to have the same look as HPV, so our cells already know what the wild HPV looks like & will know how to attack it What is Hepatitis B? -DNA virus -inflammatory disease of the liver; functions of liver degrade -get it via direct contact (body fluids, blood) -initial incubation period of 6 months, no symptoms -infects liver cells, causes inflammation, but immune cells usually kill it off & there's full recovery-10% of people: virus lysogenizes into their DNA & becomes chronic liver infection -may be asymptomatic & not know you're infected -can lead to cirrhosis (shrinking, hardening, scarring) of liver -may have jaundice (yellow tinge on skin/eyes) -increased risk of liver cancer -vaccine HIB can prevent this What are RNA viruses? -do not lysogenize into host cell -associated w/ many important emerging diseases -assigned to groups based upon structure What is Polio? -RNA virus -transmission via fecal-contaminated food/water that u consume -attacks mucous membrane in pharynx or intestines -virus replicates & sheds in throat & feces -may have mild fever-like symptoms, we usually clear the virus 99% of the time -virus will leave mucous membrane, travel to spinal cord & brain, destroy neurons that supply skeletal muscles, or paralyze your diaphragm (results in flaccid paralysis of any body part, or respiratory failure) -people that survived Polio may get Post Polio Syndrome & have muscle deterioration & Polio symptoms -Salk vaccine is an inactivated (dead) polio vaccine, multiple doses required -Sabin vaccine is an attenuated (weak, living) vaccine, taken once (orally) - although you may get Polio, is super high risk -worldwide eradication w/ Sabin vaccine is being attempted, but difficult due to war, unwillingness to accept the vaccine from outsiders due to mistaken beliefs What is HIV 1? -human immunodeficiency virus, may have originated from a chimpanzee virus -structure: two strands of single stranded RNA, GP 120 spikes on surface of envelope -transmission via direct contact (sex, blood exposure, women more likely to get it), sharing needles, or mother to baby thru placenta or breast feeding -virus cannot survive long outside the body 1) adsorption occurs when virus infects an antigen presenting cell (APC) by matching its GP 120 spikes to a CD4 receptor & CCR5 co-receptor on an APC 2) virus penetrates APC & lysogenizes into it, then the virus replicates & mutates for decades (eventually GP 120 spikes change, can now infect T Helper Cells) 3) virus now infects T Helper Cells by matching its GP 120 spikes to the CD4 receptor & CXCR4 co-receptor on a T Helper (once infected, immune response cannot function) -AIDS is when Helper T Cell count goes below 200 cells per microliter of blood4) synthesis occurs: reverse transcriptase turns single RNA into double DNA, Integrase lysogenizes virus DNA into host DNA, RNA polymerase reads host DNA to make viral mRNA, viral mRNA enters ribosomes, makes new virus parts 5) maturation of virus occurs 6) release occurs thru budding -symptoms: may show no symptoms for 3 months, or have flu-like symptoms then an asymptomatic phase for 2-15 years while being contagious...as HIV destroys the immune system you have AIDS when your T cells reach below 200, & you feel fever, swollen lymph nodes, cancer, tuberculosis -protection from HIV 1: +no vaccine available - too high mutation rate +condoms, circumcision (HIV has nowhere to hide) +no cure, therapies only slow virus replication +AZT mimics nucleotides & blocks reverse transcriptase to shut down replication (but can also affect our cells, causing aplastic anemia) +Raltegravir inhibits integrase +HAART is a cocktail of antiviral drugs, can be very effective w/ extreme side effects that make people want to come off treatment What are viroids? -not viruses, instead an infectious particle -consists of collapsed circle of RNA that can infect cells -damages host cell by cutting other RNA molecules (usually infects plants) What are prions? -not viruses: instead an infectious particle -consist of mis-folded proteins, no genetic info -can kill neurons -resistant to sterilization techniques (heat, chemicals) -does not cause immune response since host cell doesn't recognize it as threat -cause transmissable spongiform encephalopathies (holes in brain) which may be linked to Alzheimers or Parkinsons -reproduce by affecting the folding of normal proteins in neurons -with a large enough # of prions, they bind together in the neuron & create long chains that cause function of neuron to degrade, then die -eventually the brain becomes spongiform (hole-y) -acquired by mutation or trauma to head, contact via food or infected tissue (like eating infected meat) -has long incubation period, & different names depending on host What is Scrapie, Mad Cow Disease, Variant Creutzfeldt Jakob Disease, Chronic Wasting Disease, Sporadic Creutzfeldt Jakob Disease, & Kuru? -Scrapie: infection in sheep -Mad Cow Disease: infection in cows -Variant Creutzfeldt Jakob Disease: infection in people, thru food -Chronic Wasting Disease: infection in deer, moose, elk-Sporadic Creutzfeldt Jakob Disease: infection in people, thru mutation -Kuru: infection in people from eating brains