BIO3310 – Chapter 11: Eukaryotic Microbes & Parasites

What protozoan parasite caused Mario’s cutaneous sores after his deployment to Iraq?

Leishmania donovani

How is Leishmania donovani transmitted to humans?

By the bite of infected desert sand flies

Which drug was prescribed to treat Mario’s leishmaniasis and what mineral does it contain?

Sodium stibogluconate (Pentostam), which contains antimony

Why are U.S. soldiers previously deployed to Iraq or Afghanistan restricted from future blood donation?

Because Leishmania parasites can persist latently and recrudesce years later, posing a transfusion risk

List the three clinical forms of leishmaniasis.

Cutaneous, mucocutaneous, and visceral (kala-azar)

Name four organelles or features found in eukaryotic cells but absent in prokaryotes.

Nucleus, linear chromosomes, endoplasmic reticulum, Golgi body (others: mitochondria, chloroplasts)

What is mitosis?

The process that evenly segregates duplicated chromosomes into two genetically identical daughter cells (asexual or vegetative reproduction)

What special modification of mitosis produces gametes in eukaryotes?

Meiosis

During meiosis, what event creates genetic recombination between homologous chromosomes?

Crossing-over while homologous chromosomes form tetrads

Define yeast.

A single-celled fungus capable of both asexual and sexual reproduction

Which yeast is widely used in food production and shows alternation of generations?

Saccharomyces cerevisiae

In S. cerevisiae, what triggers haploid cells to become gametes and fuse into a diploid zygote?

Stressful environmental conditions

Name two medically important Candida species and their significance.

Candida albicans – causes thrush & vaginitis; Candida auris – multidrug-resistant healthcare-associated infection

What is a dimorphic fungus? Give an example.

A fungus that can grow as both yeast and filamentous forms; example: Candida albicans

Which two fungal components are prime antifungal drug targets and what drug classes inhibit them?

Chitin (targeted by nikkomycin Z) and ergosterol (targeted by triazoles)

What tough polysaccharide strengthens fungal cell walls?

Chitin

Describe a mycelium.

The branching network of hyphae produced by filamentous fungi

What are microsporidia?

Spore-forming organisms closely related to fungi that reproduce sexually and asexually

Differentiate lobed vs filamentous amoebas.

Lobed amoebas possess large, bulky pseudopods; filamentous amoebas have thin, needle-like pseudopods

Which protozoan causes intestinal amebiasis and what are its two stages?

Entamoeba histolytica; stages: trophozoite (feeding) and cyst (dormant)

How do ciliates move and capture prey?

Via ATP-driven rhythmic beating of cilia that also sweep food into an oral groove

What sexual process do ciliates use to exchange genetic material?

Conjugation involving fusion of haploid micronuclei

What specialized structure allows apicomplexans to enter host cells?

The apical complex

Identify the definitive and intermediate hosts in malaria.

Definitive host: mosquito (sexual stage); Intermediate host: human (asexual stage)

Name two major human malaria species.

Plasmodium falciparum and Plasmodium vivax

Which apicomplexan is transmitted via cats and can cross the placenta?

Toxoplasma gondii

What organelle provides motility energy in trypanosomes?

Kinetoplast, a specialized mitochondrion

Give one disease caused by each: Trypanosoma brucei, Trypanosoma cruzi, Leishmania donovani.

T. brucei – sleeping sickness; T. cruzi – Chagas’ disease; L. donovani – leishmaniasis

Why are Giardia lamblia and Trichomonas vaginalis classified as metamonads?

They are flagellated parasites that lack mitochondria and use anaerobic metabolism

What marine algal group causes “red tide” and produces neurotoxins?

Dinoflagellates

Distinguish nematodes, trematodes, and cestodes by body plan.

Nematodes – cylindrical roundworms with complete digestive tube; Trematodes – flat flukes with blind gut; Cestodes – tapeworms lacking digestive tract, absorb nutrients through skin

Which nematode species causes the most prevalent helminth infection in the U.S.?

Enterobius vermicularis (pinworm)

Describe the lifecycle path of hookworms after skin penetration.

Enter blood → travel to lungs → penetrate alveoli → ascend to throat → swallowed → attach to small-intestinal lining and suck blood

What helminth causes trichinosis and how is it acquired?

Trichinella spiralis; ingesting raw or undercooked pork containing cysts

What feature identifies tapeworm segments (proglottids) in stool?

Rectangular segments each containing male and female reproductive organs packed with eggs

How can cestode larvae (cysticerci) reach human tissues other than the intestine?

Some eggs or larvae migrate via blood to muscle, brain, or liver forming cysts

Define arthropod ectoparasite and give two examples that act as disease vectors.

An external parasite with jointed appendages that feeds on hosts; examples: Ixodes ticks (Lyme disease) and body lice (epidemic typhus)

What arachnid burrows into skin causing scabies?

Sarcoptes scabiei mite

Which clicker question identified a eukaryote-specific organelle absent in prokaryotes, and what is the answer?

Golgi body

A segmented parasite with both sexes in each segment causing malnutrition is most likely a .

Tapeworm (cestode)

Single-celled fungi such as Candida albicans are classified as .

Yeasts