Apicomplexan Parasites Flashcards
Giardia belongs to which phylum?
Metamonida
Characteristics of Apicomplexa?
- Pellicle which determines the crescent shape
- Apicoplast= a non-photosynthetic plastid
- Apical complex
- Gliding motility
- Sexual and asexual reproduction
What is the pellicle made up of?
The plasma membrane, the inner membrane complex, subpellicular microtubles and alveolin network
What is the IMC made up of?
Inner and outer membrane
What links the IMC to the subpellicular microtubules?
Network of alveolins
What is the apical complex?
A group of cytoskeletal structures (conoid, apical ring, pre-conoidal ring) and membrane bounded organelles which include: rhoptries (club shaped), micronemes…
What are the two secretory organelles found in the apical complex?
Rhoptries and micronemes
Which stage of the Plasmodium parasite lacks rhoptries?
Ookinete
Apical complex is involved in?
Gliding motility, cell attachment, cell invasion
What genomes are there in Apicomplexa?
Nuclear genome
Mitochondrial gene
Apicoplast genome
The apicoplast genome is how large?
35kb
Shape of the apicoplast genome?
Circular
What are the 4 major species of Plasmodium that can infect humans?
Malariae, ovale, vivax and falciparum
What are the motile stages of Plasmodium infection?
Ookinete
Sporozoite
What is the non-motile stage of Plasmodium infection?
Merozoite
What is the motile stage of Toxoplasma infection?
Tachyzoite
Male microgametocyte must undergo?
3 rounds of division to produce 8 microgametes which are released from the RBC in a process known as exflagellation
How many of the human population are infected with Toxoplasma?
An estimated 1/3 of the global population
Toxoplasma definitive host?
Members of felidae
Sporulation of Toxoplasma occurs?
In the environment
Only the sporulated cysts are?
Infectious
Tachyzoites are involved in what type of infection?
Acute infection
Bradyzoites are involved in what type of infection?
Chronic infection
Toxoplasma infection of cats is?
Gut limited
What is the main cause of death in HIV patients?
Toxoplasmosis
Micronemes are involved in?
Gliding motility and cell entry
Rhoptries are involved in?
Cell entry
Subpellicular microtubules determine the trajectory of the Apicomplexan parasites which is?
The left handed spiral arrangement of the subpellicular microtubules results in a clockwise corkscrew trajectory
What is the apicoplast?
A plastid which is present in the majority of Apicomplexan members
It is a non-photosynthetic plastid
What is the function of the apicoplast?
Involved in many anabolic pathways including biosynthesis of fatty acids, isoprenoids, iron-sulfur clusters and heme
Apicoplast is surrounded by how many membranes?
4 membranes
What do proteins that are transported to the apicoplast possess?
Bipartite targeting sequence
N terminus
Signal peptide
Transit peptide
What does the signal peptide do?
Targets the protein for the secretory pathway
The signal peptide is cleaved in the ER to reveal the transit peptide
What does the transit peptide do?
Causes transportation of the protein through the multiple membranes of the apicoplast where it is then cleaved to reveal the mature protein
What phenomenon is witnessed upon apicoplast destruction?
Delayed death phenomenon. Upon destruction of the apicoplast the parasite does not die straight away, it is unable to infect cells subsequently
Transcription and translation machinery in the apicoplast is of what origin?
Prokaryotic origin
Fluoroquinolone action?
Prevent DNA replication by inhibiting DNA gyrase or topoisomerase IV
Rifampin action?
Prevents transcription by inhibiting DNA dependent RNA polymerase
Fatty acids are assembled how many carbon atoms at a time?
Two carbon atoms at a time
What synthesises fatty acids?
Fatty acid synthase
How many fatty acid synthesis pathways are there?
Two
What is the fatty acid synthesis pathway in vertebrates?
Type I pathway
What is the fatty acid synthesis pathway in prokaryotes?
Type II pathway
Fatty acid synthase of the type I pathway?
A large multifunctional polypeptide
Fatty acid synthase of the type II pathway?
Made up of individual enzymes- distinct individual proteins. Each protein catalyses a single step in the reaction pathway.
Isoprenoid biosynthesis in vertebrates is?
Mevalonate dependent
Isoprenoid biosynthesis in parasites is?
Mavalonate independent… DOXP pathway
Artemisinin is derived from?
Sweet wormwood
Artemisinin was discovered by?
Tu YouYou a Chinese scientist
