BIOL 203 - Final Study Flashcards
What are micronemes?
Organelles found in Apicomplexans
Responsible for releasing proteins (adhesins) and other components that allow the parasite to invade host cells.
Initiate host-cell recognition and and anchoring.
What are four types of locomotion in protists?
Flagellar swimming, Amoeboid locomotion, Cilliates walking with cirri, Gliding
Where are raphe found and what does it do?
Raphe are slits found in the frustule of pennate diatoms.
It is a slit that allows them to connect to a substrate by secreting a sticky saccharide called mucilage.
Myosin and gliding in diatoms
Myosin is a motor protein that moves along microfilaments.
Adhesive mucilage attaches to transmembrane protein complexes which are subsequently attached to myosin.
Myosin moves towards the posterior of the cell pulling the diatom along the surface.
When myosin reaches the end of the actin road, the mucilage is cleaved and the myosin is recycled to the anterior of the cell to repeat the process.
Flagellar gliding in Chlamydomonas
Dyeins act on modified IFT trains while the glycoproteins attach to the substrate for traction.
The movement of the dyeins towards the base of the flagellum pulls the cell in the opposite direction.
Intraflagellar transport (IFT) trains
Complexes used to transport proteins up and down the flagellum.
Carried along the axoneme by Kinesin and Dyein.
Fused to glycoproteins (sticky) in plasma membrane.
Apicomplexan gliding
Myosin is attached to a protein complex that transverses the alveoli and is attached to the cells cytoskeleton.
Transmembrane proteins bind to short transient actin filaments via more proteins and host cell receptor.
When actin is pushed by the motor protein the apicomplexan moves.
Cell moves in same direction as myosin.
What constitutes gliding?
Happens on substrate
Utilizes cytoskeleton, motor and transmembrane proteins
Steps of apicomplexan parasitism
Micronemes release adhesins
Create parasitophorous vacuole
Rhoptries discharge lipids and proteins that modifies the membrane of the vacuole to avoid it being destroyed.
Dense granules release lipids and proteins that change the content of the P.V. to create optimal conditions for survival and replication.
Dense granules function
Discharge content in last step of apicomplexan parasitism to change the content of the lumen of the P.V. to create optimal conditions.
Rhoptries function
Discharge lipids and proteins to modify the membrane of the parasitophorous vacuole to keep it from being targeted and destroyed.
Very basically, what happens when a new parasite is introduced to the human immune system?
Something on the parasite’s surface (protein, sugar, etc..) is identified as a target. This molecule is an antigen.
The immune system synthesizes a novel protein that can bind to the antigen: an antibody.
Antibodies are mass produced, targeting the parasite and/or by guiding white blood cells to destroy it.
After the infection is cleared, some antibodies are stored for future purposes.
How do trypanosomes avoid the immune system?
Trypanosomes cover themselves in Variant Surface Glycoproteins (VSG).
When the immune system starts producing antibodies targeted at VSG it sheds the VSG and produces a brand new coat of proteins VSG2.
Pseudogenes
A gene not used over multiple generations accumulates deleterious mutations and becomes non-functional.
What are the three ways Trypanosoma brucei increases variability?
Switching which chromosome has its VSG gene expressed.
Moving a VSG gene from an inactive upstream pool into the expressed site via recombination (few hundred options).
Recombining pieces of genes and pseudogenes to create a new chimeric or mosaic of VSG genes.
Steps of microsporidian infection
Water is absorbed by vacuole increasing intracellular pressure.
Chitin wall breaks at weak point and the polar filament everts
Everted polar filament (Polar tube) pierces the host membrane.
Organelles are pushed through the polar tube where new cells form inside the host. (extra membrane material comes from the polaroplast)
Polar tube breaks with most organelles are now in a newly formed cell inside host.
Unusual genes in the nuclear genome of trypanosomes.
Arranged in long linear clusters.
Don’t have typical promoters.
Transcribed in long polycistronic mRNA’s
Spliced leader is
Three main features of ciliates?
Cilia
Nuclear dimorphism
Conjugation
