The Eukaryotes: Fungi, Algae, Protozoa and Helminths Flashcards
List the defining characteristics of fungi.
They have hyphae
They also have mycelium
Molds are mostly filamentous
Yeasts are non filamentous, unicellular fungi; budding yeasts divide asymmetrically.
Fungi can be dimorphic
Contain reproductive fungal spores
They like environments which are hostile to bacteria
They can metabolize complex carbohydrates such as lignin in wood.
Hyphae
each of the branching filaments that make up the mycelium of a fungus.
Mycelium
Mass of hyphae.
Fungi are dimorphic, what does this mean?
fungi can grow as ether mold or yeast depending on the temperature; yeasts like 37 degrees celsius and molds like 25 degrees celsius.
How do fungal spores differ from bacterial spores?
fungal spores are formed from aerial hyphae, they are not as resistant as bacterial spores, they are true reproductive spores.
Fungi like to grow in environments not suitable to bacteria, what are some of these environmental factors?
they like low pH (acidity)
they prefer low moisture
They like high osmotic pressure (lots of salt or sugar)
What are two beneficial and two harmful aspects of fungi?
Fungi can be used to kill pests such as termites, they can also be used to make bread, beer, and HBV vaccine. Fungi can be harmful because they can cause food spoilage (mold) or disease
List the defining characteristics of protozoa.
Unicellular, eukaryotic chemoheterotrophs. Large and diverse group. Few are pathogenic.
Found in soil and water and as normal microbiota in animals.
Trophozoite: Vegetative form (feeding and growing).
Asexual reproduction via fission, budding, or schizogony (multiple fission).
Sexual reproduction via conjugation.
Some protozoa can produce a cyst that provides protection during adverse environmental conditions.
Differentiate an intermediate host from a definitive host.
A definitive host is a host in which a parasite reaches sexual maturity (adult stage) . An intermediate host is a host in which a parasite passes one or more of its asexual stages (larval stage), usually designated first and second if there is more than one
List the distinguishing characteristics of the two classes of parasitic helminths, and give an example of each
a
Provide a rationale for the elaborate life cycles of parasitic worms
a
Define arthropod vector
arthropods that carry pathogens that cause disease
Differentiate between a tick and a mosquito, and name a disease transmitted by each.
A tick is part of the class arachnida and has 8 legs in its adult form, it cannot fly. A mosquito is part of the class insecta and has 6 legs, mosquitos can fly. An example of a tick borne disease would be lyme disease, and an example of a mosquito borne disease would be malaria.
List the causative agent, mode of transmission, and clinical symptoms of scabies
- caused by Sarcoptes scabiei
- transmitted by direct skin to skin contact with the infected or indirect contact with fomites such as linens or clothing.
- symptoms include intense itching and pimple-like skin rash
chemoheterotrophic fungi
has to ingest carbon for energy and nutrition; does this by absorption, it recycles nutrients and returns them to the soil.
What are the oxygen requirements of mold?
they are aerobic
What are the oxygen requirements of yeasts?
They are facultatively anaerobic
Mycology
The study of fungi
Most fungi are ____________, few are __________ of plants and animals.
decomposers
parasites
the number of serious fungal infections is _______________.
on the rise
Not all fungi make ___________.
mushrooms
cells in hyphae release __________ so fungus can absorb nutrients and make _________.
enzymes
ATP
The mushroom is the _____________ body of a fungus and produces _________ which are released from its ________, the remaining __________ is under ground
reproductive
spores
gills
mycelium
How is yeast used in HBV vaccine?
it is used as an adjuvent or additive to the vaccine to help increase the body’s immune response.
Mycoses
fungal diseases
Systemic mycosis
infection deep within body, affects many tissues and organs. Histoplasmosis and coccidiomycosis.
Subcutaneous mycosis
Caused by saprophytic fungi, e.g.: Sporotrichosis.
Cutaneous mycosis/ Dermatomycosis
affects keratin-containing tissues (hair, nails, skin).
Superficial mycosis
localized on hair shafts and superficial skin cells.
Fungus alone has only a minimal capacity to damage skin directly. Superficial mycoses affect approximately 9 million Americans and account for 5% of skin diseases. These fungi invade only the dead or keratinized layers of the skin, hair and nails.
Opportunistic mycoses
caused by normal microbiota or fungi that are not usually pathogenic (E.g.: Candidiasis and Pneumocystis pneumonia)
usually systemic
Algae
Mostly photoautotrophs (photosynthetic), mostly in ocean; two kinds, diatoms and dinoflagellates
Diatoms
- Unicellular, store energy in form of oil
- Domoic acid causes Neurological disease
- Ingestion of mussels that fed on diatoms can cause intoxication (also affects birds and sealions)
Dinoflagellates (plankton)
- Some produce neurotoxins: red tide
- Kills fish, marine mammals, and humans, e.g.: parasitic shellfish poisoning (PSP)
Medically Important Protozoa
Arcaezoa
Microspora
Amoebozoa
Apicomplexa
Euglenozoa
Euglenozoa
Hemoflagellates- any parasitic flagellate protozoan that lives in the bloodstream.
- move by flagella
Trypanosoma
Apicomplexa
- not mobile
- intracellular
Plasmodium, Babesia, Toxoplasma, Cryptosporidium
Amoebozoa
- Cause Amoebiasis
(move via pseudopodia or pseudopods) Entamoeba histolytic (dysentery; secretes enzymes that breakdown tissue) and Acanthamoeba (eye infection)
Microspora
(no mitochondria and no microtubules) – diarrhea and keratoconjunctivitis in AIDS patients
Arcaezoa
(lack mitochondria)
Trichomonas - trichomoniasis
Giardia – severe, explosive diarrhea
What is trichomoniasis?
Trichomoniasis (or “trich”) is a very common sexually transmitted disease (STD) that is caused by infection with a protozoan parasite called Trichomonas vaginalis. Although symptoms of the disease vary, most women and men who have the parasite cannot tell they are infected.
How common is trichomoniasis?
Trichomoniasis is considered the most common curable STD. In the United States, an estimated 3.7 million people have the infection, but only about 30% develop any symptoms of trichomoniasis. Infection is more common in women than in men, and older women are more likely than younger women to have been infected. Symptoms: itching, burning during urination, discharge with foul odor.
How do people get trichomoniasis?
The parasite is passed from an infected person to an uninfected person during sex. In women, the most commonly infected part of the body is the lower genital tract (vulva, vagina, or urethra), and in men, the most commonly infected body part is the inside of the penis (urethra). During sex, the parasite is usually transmitted from a penis to a vagina, or from a vagina to a penis, but it can also be passed from a vagina to another vagina. It is not common for the parasite to infect other body parts, like the hands, mouth, or anus.
What is the result of Babesia parasites infecting and destroying red blood cells?
babesiosis can cause a special type of anemia called hemolytic anemia. This type of anemia can lead to jaundice (yellowing of the skin) and dark urine
Toxoplasmosis
is considered to be a leading cause of death attributed to foodborne illness in the United States. More than 60 million men, women, and children in the U.S. carry the Toxoplasma parasite, but very few have symptoms because the immune system usually keeps the parasite from causing illness.
However, women newly infected with Toxoplasma during pregnancy and anyone with a compromised immune system should be aware that toxoplasmosis can have severe consequences – miscarriage, stillbirth, blindness, mental disability, and seizures.
Cryptosporidiosis
caused by cryptosporidium- watery diarrhea; especially dangerous for AIDS patients or immunocompromised patients
Trypanosomes
a class of protozoa that cause Chaga’s disease (S. America - transmitted by kissing bugs) and Sleeping Sickness (Africa - transmitted by Tsetse fly). In sleeping sickness, the parasite is transmitted by the bite of the fly and after a few weeks, crosses the BBB to cause confusion, mental deterioration, balance problems, and comatose state, followed by death. In Chaga’s disease, “there may be fever or swelling around the site of inoculation (where the parasite entered into the skin or mucous membrane). Rarely, acute infection may result in severe inflammation of the heart muscle or the brain and lining around the brain.” Severe cases may result in dilated heart , esophagus, or colon, and heart arrythmia that can cause sudden death.
break down trypanosomes the word.
trypano- = Borer
-some = Body
schizogony
Schizogony is the process of asexual reproduction during which the nucleus undergoes division preceding cell division. Schizogony produces daughter cells known as merozoites, which can develop in to gametocytes or enter new host cells and undergo another cycle of schizogony. Gametocytes, which are derived from merozoites, are cells that are capable of developing into gametes – male and female gametocytes. These are ingested by mosquitos, and once inside the mosquito, the gametocytes unite (sexual reproduction) to form zygotes. Zygotes mature into sporozoites and are transmitted when the infected mosquito bites another human.
in the case of Plasmodium vivax a causative agent of malaria what is the reservoir? and what is the vector?
a human or any animal that carries P. vivax sporozoites. Mosquitos are the vectors because they spread the pathogen that causes the disease.
Describe the life cycle of Plasmodium vivax. What type of transmission is described?
- Transmission to host by mosquito in sporozoite form
- Schizogony of P. vivax occurs in liver of the host; merozoites are produced
- Merozoites released into bloodstream to infect red blood cells
- Merozotie enters ring stage in RBC
- ring stage grows and divides, producing merozoites
- Merozoites lyse RBC
- Merozoites mature into gametocytes (sexually mature) and are ingested by mosquito vector
- inside mosquito gametocytes unite to form a zygote
- Zygotes mature into sporozoites
* this is an example of biological transmission.
Helminths
parasitic worms
helminths are part of the kingdom ________, they are _________ _________ parasites.
Animalia
multicellular-animal
The phylum Platyhelminthes includes ________ and is divided into the classes ________ and _________
flatworms
Trematodes (flukes)
Cestodes (tapeworms)
The phylum Nematoda includes ___________.
roundworms
few helminths are ___________ parasites.
human
the anatomy and life cycle of helminths are modified for parasitism, give examples of this.
Reduced digestive system
Reduced nervous system
Reduced locomotion
Complex reproduction
what pathogens cause malaria?
Human malaria is caused by four different species of Plasmodium: P. falciparum, P. malariae, P. ovale and P. vivax.
Monoecious (hermaphroditic
Male and female reproductive systems in one animal
Dioecious
Separate male and female
Describe the life-cycle of a helminth.
- can ether be monoecious or dioecious
- Egg —-> larva(e) —–> adult
Platyhelminths
- Dorsoventrally flattened
- Trematodes and cestodes
Trematodes
or flukes have oral and ventral suckers which attaches to host tissue
Cestodes
or tapeworms have a scolex (head), proglottids
Proglottid
one of the segments or joints of a tapeworm, containing complete reproductive systems, usually both male and female
Scolex
the anterior end of a tapeworm, bearing suckers and a rostellum hooks for attachment.
gravid
pregnant; carrying eggs or young.
rostellum
Rostellum /ˌrɑːˈstɛlʌm/ (meaning “small beak”, from the Latin rostrum for “beak”; pl. rostella) in helminthology is a protruding part of the anterior end of soft-bodied tapeworms. It is a retractable, cone-like muscular structure that is located on the apical end of the scolex, and in most species is armed with hooks, the organs of attachment to the host’s intestinal wall.[1] It is a parasitic adaptation in some cestodes for firm attachment in the gastrointestinal tract and is structurally different from one species to another (or even absent is some species), thereby becoming an important diagnostic feature.[2][3]
a mature proglottid will disintegrate and _____________.
release eggs
in the life cycles of Taenia solium and Taenia saginata what animal is the definitive host and which is the intermediate host?
humans are the definitive host and pigs or cattle are the intermediate hosts.
Describe the life cycle of T. solium and T. saginata.
- eggs or gravid proglottids are in feces are passed into the environment
- Cattle (T. saginata) and pigs (T. solium) become infected by ingesting vegetation contaminated by eggs or gravid proglottids.
- larva hatch in the cattle/pigs and penetrate their intestinal and circulate to the musculature. larva develop into cysticerci in the muscle tissue
- Humans then become infected by consuming raw or undercooked meat.
- The scolex of T. solium and T. saginata attach to the intestine
- Adult worms live in large intestine
What is the stage at which infection with T. solium or T. saginata occurs in humans?
when larvae are present in the muscle tissue of the animals
At what stage can a Taenia solium or Taenia saginata infection be detected in a human?
When eggs or gravid proglottids are present in feces
Nematodes
round worms
nematodes have a _____________ digestive system.
complete digestive system
what causes nematode infections for humans?
ingesting eggs
Ascaris lumbricoides
Ascariasis. 2nd most common worm infection in US. (Most common worldwide)
Enterobius vermicularis
(pinworm). Most common worm infection in US (30% of children, 16% of adults infected)
Live in human rectum. While infected person sleeps, female pinworms leave intestines through anus and deposit eggs on surrounding skin.
Diagnosis with cellophane tape (scotch-tape test) first thing in the morning.
Self limiting, but treatment of all family members recommended.
How is pinworm disease diagnosed?
Diagnosis with cellophane tape (scotch-tape test) first thing in the morning. Do test immediately after waking up.Several samples might need to be examined.
Since scratching of the anal area is common, samples taken from under the fingernails may also contain eggs.
Hook worms
Ancylostoma duodenale and
Nectar americanus
Have a hook mouth which attaches to intestinal mucosa
Hookworms are infective during their larval (filariform larva) stage when they can penetrate skin. Adults live in small intestine and eggs are shed in feces. before the filariform stage larva are in their rhabditiform larval stage when they hatch from the egg.
Trichinellosis
is caused by Trichinella spiralis. These parasites enter the environment as cysts shed in human waste. Pigs then become infected when eating contaminated food. Larvae emerge from cysts in pig’s intestine. The larva then migrate to the muscles of the pig and form cysts. When raw or undercooked pork is consumed by a human the human becomes infected. The infection starts in the intestines and then spreads to the muscles.
Dirofilaria immitis
Heart worm
Primarily in dogs and cats
Can cause human heart failure, worms can also infect
human lungs
Spread via mosquitoes
Arthropods can be ___________. Arthropods that carry disease are called ___________.
vectors, vectors
What kingdom are arthropods part of?
Animalia
Arthropoda
a phylum of organisms that have exoskeleton, jointed legs, segmented body.
What class are lice, fleas, mosquitoes in?
Insecta (6 legs)
What class are mites and ticks in?
Arachnida (8 legs)
What is the best method of decreasing vector borne diseases?
Elimination of vectorborne diseases best via control or eradication of vectors.
How do arthropods spread disease?
Mechanical transmission
Biological transmission
Microbe multiplies in vector
What is the causative agent of scabies?
Caused by human itch mite Sarcoptes scabiei var. hominis
How does scabies mites cause disease?
They burrow into the skin and lay eggs.
What are the symptoms of a scabies infection?
Intense itching and a pimple-like skin rash
How is scabies acquired?
Spread by direct, prolonged, skin-to-skin contact with infected person
To who and where is scabies most likely to be a problem?
Occurs worldwide and affects people of all races and social classes
Nursing homes, extended-care facilities, and prisons are often sites of scabies outbreaks
How is scabies diagnosed?
Diagnosis: skin scraping, visible mites
Is scabies a vector?
Scabies is NOT a vector – it is the causative agent of disease! It is a member of the animal kingdom (like all arthropods), but does not transmit microbes.
Guinea worm
Nearly eradicated – “It will be the first parasitic disease to be eradicated and the first disease to be eradicated without the use of a vaccine or medicine.”
“It is contracted when people consume water from stagnant sources contaminated with Guinea worm larvae.
Inside a human’s abdomen, Guinea worm larvae mate and female worms mature and grow. After about a year of incubation, the female Guinea worm,one meter long, creates an agonizingly painful lesion on the skin and slowly emerges from the body. Guinea worm sufferers may try to seek relief from the burning sensation caused by the emerging worm and immerse their limbs in water sources, but this contact with water stimulates the emerging worm to release its larvae into the water and begin the cycle of infection all over again.”
Community-based intervention: teach infected people to avoid drinking water sources, teach people to prevent infected persons from entering water sources, and education and supplies for proper water filtration.
