What are the characteristics of Excavata protists?
Many of the protist species classified into the supergroup Excavata are asymmetrical, single-celled organisms with a feeding groove “excavated” from one side. This supergroup includes heterotrophic predators, photosynthetic species, and parasites.
What is the supergroup of Excavata?
Many of the protist species classified into the supergroup Excavata are asymmetrical, single-celled organisms with a feeding groove “excavated” from one side. This supergroup includes heterotrophic predators, photosynthetic species, and parasites. Its subgroups are the diplomonads, parabasalids, and euglenozoans.
Are excavates photosynthetic or non-photosynthetic?
Except for Euglenozoa, they are all non-photosynthetic. Most excavates are unicellular, heterotrophic flagellates. Only the Euglenozoa are photosynthetic. In some (particularly anaerobic intestinal parasites), the mitochondria have been greatly reduced.
What are the characteristics of Excavata?
Bottom: Metamonada, 1-anterior flagella, 2-parabasal body, 3-undulating membrane, 4-posterior flagellum, 5-nucleus, 6- axostyle. Excavata is a major supergroup of unicellular organisms belonging to the domain Eukaryota. It was first suggested by Simpson and Patterson in 1999 and introduced by Thomas Cavalier-Smith in 2002 as a formal taxon.
Are Excavata autotrophic or heterotrophic?
Many of the protist species classified into the supergroup Excavata are asymmetrical, single-celled organisms with a feeding groove “excavated” from one side. This supergroup includes heterotrophic predators, photosynthetic species, and parasites. Its subgroups are the diplomonads, parabasalids, and euglenozoans.
Do Excavata have mitochondria?
A second Excavata subgroup, the parabasalids, also exhibits semi-functional mitochondria. In parabasalids, these structures function anaerobically and are called hydrogenosomes because they produce hydrogen gas as a byproduct. Parabasalids move with flagella and membrane rippling.
Is Excavata anaerobic?
Excavata mostly consists of flagellated protozoa, many of which are anaerobic and/or parasitic.
Which group of excavates includes photosynthetic members?
Diatoms are part of a larger group known as the stramenopiles. a member of a protist group that includes photosynthetic forms in which two flagella project through armor-like plates; abundant in oceans; can reproduce rapidly, causing "red tides." Dinoflagellates are part of a larger group known as the alveolates.
How does Excavata eat?
They pull the food into the groove with a water current generated by beating flagella at the back of the groove. Excavata have two, four or more flagella. They can have discoid mitochondria, tubular mitochondria, or no mitochondria at all. Some lack the feeding groove.
Is Excavata aerobic?
Excavata exhibits a continuum in mitochondrial forms, ranging from classical aerobic, cristae-bearing mitochondria to mitochondria-related organelles, such as hydrogenosomes and mitosomes, to the extreme case of a complete absence of the organelle.
Are Archaeplastida photosynthetic?
Archaeplastida ('ancient plastids') are the group containing essentially all of the primary algae (i.e., with plastids of primary endosymbiotic origin – see above), and the great majority of living species in this assemblage are photosynthetic.
Do Heterolobosea have chloroplasts?
The uncharacterized members of the dynamin family (grouped in purple in Fig. 1) are widespread in eukaryotes, including plants and algae, and three other eukaryotic groups which do not have chloroplasts (Amoebozoa, Heterolobosea, and Jakobidae).
Is spirogyra photosynthetic or heterotrophic?
Some protists are autotrophic, others are heterotrophic. Recall that autotrophs make their own food through photosynthesis or chemosynthesis (see the Photosynthesis concepts). Photoautotrophs include protists that have chloroplasts, such as Spirogyra. Heterotrophs get their energy by consuming other organisms.
Are Kinetoplastids autotrophic or heterotrophic?
Kinetoplastids (e.g., Trypanosoma and other parasites) are heterotrophic flagellates and were once thought to be related to other zooflagellates.
Do Amoebozoa have mitochondria?
The Amoebozoa includes some organisms that are known to have mitosomes but also organisms that have aerobic mitochondria.
Are Rhizaria heterotrophic?
Two major subclassifications of Rhizaria include Forams and Radiolarians. Forams are characterized as unicellular heterotrophic protists that have porous shells, referred to as tests, which can contain photosynthetic algae that the foram can use as a nutrient source.
Do Amoebozoa have mitochondria?
The Amoebozoa includes some organisms that are known to have mitosomes but also organisms that have aerobic mitochondria.
Do Alveolata have mitochondria?
Alveolates have mitochondria with tubular cristae (invaginations), and cells often have pore-like intrusions through the cell surface. The group contains free-living and parasitic organisms, predatory flagellates, and photosynthetic organisms.
Do diplomonads have mitochondria?
The diplomonads have anaerobic metabolism and lack conventional mitochondria, so they were thought to be pre-mitochondriate organisms.
Do parabasalids have mitochondria?
The parabasalids lack mitochondria and are anaerobic; they all have a unique cellular organelle, the hydrogenosome, which is a relic of the mitochondrion and serves as the site of anaerobic pyruvate metabolism.
What is the supergroup of excavata?
Many of the protist species classified into the supergroup Excavata are asymmetrical, single-celled organisms with a feeding groove “excavated” from one side. This supergroup includes heterotrophic predators, photosynthetic species, and parasites. Its subgroups are the diplomonads, parabasalids, and euglenozoans.
What is the name of the second subgroup of excavata?
Parabasalids. A second Excavata subgroup, the parabasalids, are named for the parabasal apparatus, which consists of a Golgi complex associated with cytoskeletal fibers. Other cytoskeletal features include an axostyle, a bundle of fibers that runs the length of the cell and may even extend beyond it. Parabasalids move with flagella and membrane ...
Excavata Definition
Excavata is a supergroup of protists that includes unicellular asymmetrical organisms. These organisms can be photosynthetic, heterotrophic, or parasite.
Overview of Excavata
Protista is a unicellular eukaryotic organism and is closely related to plants, animals, and fungi. The structure of protists varies from species to species. They live in a colony. Most organelles in Protista are the same as plants, animals, and fungi. Excavata are one of the supergroups of Protista.
Introduction
Protista is a unicellular eukaryotic microorganism. Protists form a colony. They are found in water and damp terrestrial habitats, or they may be a parasite. They are considered as the first eukaryote form of life on earth. Protista includes slime mold, diatoms, water molds, etc. They are all microscopic organisms.
Characteristics of Excavata
Excavates have many characteristic features that help them be identified and distinguished from other organisms. Excavates are free-living as well as symbiotic in forms. Some of the other general characteristic features of Exacavates are as follows:
What is excavata taxa?
The Excavata includes taxa that are photosynthetic, parasitic, symbiotic and heterotrophic. Many of the taxa lack mitochondria, and, therefore, seemed to conform to the requirements of an archaic premitochondrial ancestor of all eukaryotes. This theory, called the Archezoa Hypothesis, was created by Cavalier-Smith (1983). [Go to Domain Eukarya for an elaboration on the Archezoa Hypothesis.]
What is the feeding groove of an archezoa?
Patterson (1999) and Simpson and Patterson (2001) defined a striking structural similarity that many of the former archezoan taxa possessed, a feeding groove called an excavate. The excavate was a groove that ran longitudinally on the cell surface and was associated with at least one recurrent flagellum, which set up currents in the groove that served to concentrate suspended particles and move them to a cytostome. Simpson (2003) identified seven such groups that had such an excavate apparatus: the Core Jakobids, Malawimonas, Trimastix, Carpediemonas, Retortomonads, Diplomonads, and the Heterolobosids (amoeboflagellates). Many of the excavate taxa were mitochondriate and had clear affinities with taxa that did not bear an excavate . So, by 2003 (Simpson 2003 and Cavalier-Smith 2003b) at least 10 groups (we interpret it as 11 groups) had been identified as excava te taxa (see Table 1). Burki et al. (2008) and Hampl et al. (2009) confirmed the monophyly of the excavates by phylogenomic analyses relative to members of the other supergroups. Furthermore, the excavates appear to be a very deep-rooting group, equivalent to the unikonts (Opisthokonta), and the bikonts (Chromalveolata + Rhizaria + Archaeplastida).
What is the name of the organism with a depression or feeding groove located on the cell surface?
1. We derived the name, Euexcavatae, meaning the "true excavates", to describe those organisms with a depression or feeding groove located on the cell surface and associated with one or more flagella.
What is the main photosynthesis pigment in cyanobacteria?
All members of this clade use chlorophyll a (chl a) as their main photosynthetic pigment ( just like cyanobacteria)
Which organisms do not function in respiration?
Mitosomes: do not function in respiration at all, and no longer contain any DNA. -many parasitic, including Giardia, which causes Diarrhea (don't drink natural water) Parabasalids. Hydrogeneosomes: function anaerobic respiration, some still contain DNA.
