Protozoa Flashcards
a eukaryotic cell consists of:
nucleus, cell membrane, golgi bodies, endoplasmic reticulum, mitochondria
What features are unique to protozoa?
pellicle (modified cell membrane)
cytostme/cytoproct
contractile vacuoles
trichocysts
What does the pellicle do?
it is made up of numerous layers of cell membrane making the cell membrane rigid
How do protozoans take in food?
some by diffusion
phagocytosis (intracellular digestion)
What is phagocytosis?
membrane bound food vacuole
digestive enzymes secreted into vacuole
wastes discharged when vacuole fused to cell membrane
What is a cytostome?
oral region - food intake
What is a cytoproct?
wastes discharged
How is food moved to the cytostome?
Food is transported by currant created by cilia
What is the structure of a flagellum? & how does it move?
9 + 2 microtubules (tubulin rods - actin)
ATP req for movement
movement by contraction of Dynein arms on 1 side of flagellum
What does the water evacuation vacuole do?
stores water in cytoplasm until full then expells it
too much H2O will make the cell too dilute or rupture the cell
What is a trichocyst?
Held just within the cell it is disharged from the cell vesicle to attach to substrate or food
What is a toxicyst?
a modified trichocyst for attacking prey, secretes toxin
Why do protozoa not get larger than the 30mm deep sea amoeba?
lacks a circulatory system to move nutrients, wastes & gases
must have enough surface area to support volume through diffusion
cell membrane : cytoplasm ratio
What are the 4 major groups in the kingdom Protista?
Flagellates
Amoebas
Ciliates
Spore Formers
What are the Flagellate Phyla?
Trichozoa
Euglenozoa
Dinozoa
What are the characteristics of Flagellates?
- 1+ flagellum
- monomorphic nucleus
- pellicle or test
- asexual reproduction: longitudinal fissure
sexual reproduction: autogamous or flagellated gametes - autotrophic or heterotrophic
What is autogamy?
a type of sexual reproduction
an individual makes 2 gametes that fuse into a diploid cell
Why do flagellates switch between sexual and asexual reproduction?
In sexual reproduction, there are many offspring but some killed due to natural selection, the trade of DNA makes it possible to find a better combination
Asexual reproduction is good for when reproducing under low population & for building population faster.
What is the medical importance of flagellates?
Leishmaniasis - blocks spleen or capillaries causing 2ndary infection (gangreen)
What is the mortality rate of Sleeping Sickness?
80% if untreated
What is chagas disease?
latin american diease, vectored by cone-nosed bug (its digestive system) when its feces is rubbed into the bite of this blood-drinking bug
symptoms: anemia, enlarged heart
What are the characteristics of Amoebas?
- Pseudopods
- monomorphic nucleus
- naked, test
- asexual reproduction: binary fission
sexual reproduction: autogamous, flagellated gametes
What Amoeboid Phyla, are naked?
have a CaCO3 test?
have a silicaceous test?
naked: Amoebozoa
CaCO3 test: Granuloreticulosa
silicaceous test: Radiozoa, Heliozoa
How do amoebas feed?
trapping what they run into
What are the Pyramids & the White Cliffs of Dover made of?
Foraminifera (Phylum Granuloreticulosa) tests
How do Amoebas feed?
through phagocytosis with pseudopods (no pellicle), filter with net-like or spinelike actinopods
What is the medical importance of amoebas?
many endosymbiotic or parasitic species
What phylum do ciliates belong?
Ciliophora
What are the characteristics of Ciliates?
- Cilia
- Infraciliature
- pellicle, test
- heteromorphic nucleus
- Asexual reproduction: transverse fissure
sexual reproduction: autogamous or conjugation
How is the pellicle in ciliates?
thick, giving a fixed shape
How is the pellicle in amoebas?
no pellicle, thus non-fixed shape
What is the purpose of the infraciliature?
it is composed of microtubules and anchor cilia
found even if it lacks cilia
What is the movement that carries food to cytostome called?
metachronal waves
coordinated w/o nervous system
create water currents
What is a heteromorphic nucleus?
it is composed of 2 nuclei
the macronucleus & micronucleus
What is the function of the macronucleus in ciliates?
day-to-day processes
What is the function of the micronucleus in ciliates?
total genetic information, used during reproduction
What is conjugation (reproduction)?
a form of sexual reproduction,where 2 ciliates trade their micronucleus & then later replicate asexually
What phylum dp sporeformers belong to?
Sporozoa
What are the characteristics of sporozoa?
- endoparasites
- pellicle
- lack flagellum, pseudopods, cilia, have apical complex
- monomorphic nucleus
- asexual reproduction (multiple fission)
sexual reproduction (flagellated gametes)
How do sporozoa move?
undulating their body
What is the purpose of the apical complex?
its only present during the infective stage & is used for host penetration
What is the medical importance of sporozoa?
all are parasites (Malaria)
What does it mean for a sporozoa to have a complex lifecycle?
it has more than 1 host
What are the lifecycle stages for malaria?
- gametocytes - haploid in human/mosquito
- zygote - diploid in mosquito
- sporozoites - haploid, in mosquito/human
- merozoites - haploid in human
What lifecycles of malaria are found in the mosquito?
Gametocytes are picked up from RBC
fuse in gut wall to become zygotes
asexually divide into sporozoites
What lifecycles of malaria are found in the human?
sporozoites are injected into human
divide into merozoites
change into gametocyte in RBC
What is the direct filiation theory?
primitive eukaryotes arose from bacteria w/chloroplast (cyanobacteria)
other organelles evolved gradually as internal membrane bounded structures
later protozoa lost chloroplast
What is the serial endosymbiont theory?
endosymbiotic prokaryotes become membrane bound organelles in eukaryotes
