protista Flashcards
what are protista?
eukaryotes that are neither plants, animals or fungi
4 supergroups of eukarya
Excavata, SAR, Archaeplastida, Unikonta
features of protista
eukaryotic, lack highly specialised tissues, mostly unicellular, diverse, paraphyletic
what are protozoa?
unicellular heterotrophic protists
Protist roles
keystone organisms of soil ecosystems, and regulate essential processes of soil fertility such as nutrient cycling and plant growth
Excavata
excavated groove on one side in some
Unikonta
have single emergent flagellum or are amoeba with no flagella
related to fungi and animals
SAR
3 large, diverse clades with DNA similarities
- Stramenoplia
- Alveolata
- Rhizaria
Archaeplastida
red and green algae
arose through primary endosymbiosis
related to plants
3 Excavata groups
Diplomonads
Parabasilids
Euglenozoans
What are Diplomonads? Give an example
Phylum in Excavata supergroup with modified mitochondria and 2 equal-sized nuclei.
Small cells (~10 µm) with characteristic
doubled organisation and multiple flagella
Many are parasitic
eg. Giardia
What are Parabasilids? Give an example
Phylum in Excavata supergroup with modified mitochondria and an undulating membrane for locomotion.
anaerobic
all are endosymbionts with animals
eg. trichomonas
Euglenozoans
phylum in Excavata supergroup with spiral or crystalline rod inside flagella
SAR clade, 3 end-tree groups and feature
Clade = Alveoaltes
groups = Dinoflagellates, Apicomplexans, Ciliates
Feature= Have membrane-enclosed sacs (alveoli) beneath plasma membrane
Unikonta clade, 3 end-groups and feature
Clade = Amoebazoans
groups = Tubulinids, slime molds and Entamoebas
Feature = Amoebas with lobe-shaped or tube-shaped pseudopodia
What are Kinetoplastids? Give 2 examples
Group of flagellated protists in Euglenozoa phylum (Excavata) containing a single, large mitochondrion, and a kinetoplast, a granule containing an organised mass of DNA
eg. - Trypanosoma, Leishmania
What are Apicomplexans? Give 2 examples
Organisms in Alveolata phylum (SAR), mostly parasitic
eg. Plasmodium, Cryptosporidium
What are Entamoebas? Give 2 examples
genus of Amoebazoa phylum (Unikonta)
eg. Entamoeba, Naegleria
common features of Diplomonads and Parabasilids
Highly reduced mitochondria that lack DNA, e- transport chain and enzymes of citric acid cycle –> adapted for anaerobic metabolism and environments
Giardia Intestinalis/Duodenalis - what is it? what are the symptoms?
common intestinal parasite
Symptoms: diarrhoea, dehydration and intestinal pain
Giardia Intestinalis/Duodenalis - Mechanism of infection (What route?
Is a vector organism involved?)
Contamination of water, food or hands by infective cysts, ingested by human. No vector organism, just host.
Giardia Intestinalis/Duodenalis - Mechanism of the disease (What
part of the human body is affected?
How?)
Coat intestinal wall and feed on mucous secretions, affecting absorption of fatty acids
Giardia Intestinalis/Duodenalis - How can it be diagnosed?
Diagnosis is by identification of cysts or trophozoites in the faeces
Giardia Intestinalis/Duodenalis - Infective life stages
Only cysts are infective – the trophozoites do not survive in the environment, whereas cysts can remain viable for week to months.
Trophozoite
A stage in the life cycle of some protist parasites when they absorb nutrients from the host.
Cyst
A life cycle stage of a protist parasite with a protective membrane or thickened wall.
Trichomonas vaginalis - what is it?
parasite of Parabasilid phylum (Excavata) inhabiting reproductive and urinary tract of men and women
Trichomonas vaginalis - Mechanism of infection
sexual intercourse
Trichomonas vaginalis - Mechanism of the Disease & Symptoms
Causes infection when acidity of the vagina is disturbed (trichomoniasis): capillary
haemorrhage
- asymptomatic in males
- burning during urination for females
Trichomonas vaginalis - Diagnosis
cervical smear
Trichomonas vaginalis - Infective and diagnostic life stages
*Trophozoite is the only life-stage form, it cannot encyst (poor survival outside of the host)
- Diagnosable but not infective as trophozoite in vaginal and prostatic secretions and urine.
- Multiplies by binary fission
- Becomes infective trophozoite in vagina or urethra
Trypsanoma cruzi - what is it?
parasitic protozoan in Euglenozoan phylum (Excavata), causes ‘Sleeping Sickness’
Trypsanoma cruzi - Mechanism of infection
Trypsanoma cruzi - Diagnosis
Diagnosed microscopically in blood and other body fluids.
Trypsanoma cruzi - Mechanism of Disease & Symptoms
Symptoms depend on the species of Trypanosome – in humans, a vascular and
lymphatic infection is followed by an invasion of the central nervous system that gives rise to ‘sleeping’ symptoms, followed by death.
Trypsanoma cruzi - Infective and diagnostic life stages
epimastigote
replicative stage in the invertebrate host
trypomastigote
replicative stage in the mammalian host, main infective stage
metacyclic
Infective stage
outside the host body
what does ‘mastigote’ mean?
bearing flagella
