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Prokaryote or eukaryote?
This organism consists of a single cell with several flagella. It’s scientific name is Giardia lamblia. As a human parasite, it can make us sick.
Figure 1: This scanning electron micrograph revealed some of the external ultrastructural details displayed by a flagellated Giardia lamblia protozoan parasite, which is the organism responsible for causing the diarrheal disease "giardiasis". (Public Domain; US Center for Disease Control).
Protists are a group of all the eukaryotes that are not fungi, animals, or plants. As a result, it is a very diverse group of organisms. The eukaryotes that make up this kingdom, Kingdom Protista, do not have much in common besides a relatively simple organization. Protists can look very different from each other. Some are tiny and unicellular, like an amoeba, and some are large and multicellular, like seaweed. However, multicellular protists do not have highly specialized tissues or organs. This simple cellular-level organization distinguishes protists from other eukaryotes, such as fungi, animals, and plants. There are thought to be between 60,000 and 200,000 protist species, and many have yet to be identified. Protists live in almost any environment that contains liquid water. Many protists, such as the algae, are photosynthetic and are vital primary producers in ecosystems. Other protists are responsible for a range of serious human diseases, such as malaria and sleeping sickness.
The term protista was first used by Ernst Haeckel in 1866. Protists were traditionally placed into one of several groups based on similarities to a plant, animal, or fungus: the animal-likeprotozoa, the plant-like protophyta (mostly algae), and the fungus-like slime molds and water molds. These traditional subdivisions, which were largely based on non-scientific characteristics, have been replaced by classifications based on phylogenetics (evolutionary relatedness among organisms). However, the older terms are still used as informal names to describe the general characteristics of various protists.
Protists range from single-celled amoebas to multicellular seaweed. Protists may be similar to animals, plants, or fungi.
- Kingdom Protista includes all eukaryotes that are not animals, plants, or fungi.
- Kingdom Protista is very diverse. It consists of both single-celled and multicellular organisms.
- What are protists?
- How are unicellular protists and multicellular protists similar?
- How are protists classified? What are the main categories of protists?
1. PELLICLE&mdashstiff outer membrane of euglena and paramecium
6. WATER&mdashwhere ameba and paramecium live
7. PORE&mdashindentation in paramecium whree food is taken in mouth ___
9. FISSION&mdashtype of asexual reproduction, binary _____
11. CONJUGATION&mdashsexual reproduction in paremecium
13. CILIA&mdashstructures that help paramecium move
15. HETEROTROPH&mdashan organism that must consume food
16. MOVE&mdashProtozoan are classified by how they _____
17. AMEBA&mdashthe name of this protist means "change"
19. PSEUDOPODIA&mdashname means "false foot"
21. PROTOZOA&mdashname means "first animal"
22. DYSENTERY&mdashcan be caused by amebas in drinking water
24. ALGAE&mdashautotrophic, plant-like protists
25. CYST&mdashformed by ameba during unfavorable conditions
26. CHLOROPLAST&mdashorganelle that carries out photosynthesis
27. VACUOLE&mdashwhere food is digested food _______
28. ENDOPLASM&mdashcytoplasm located in the interior of the cell
2. CONTRACTILE&mdashremoves excess water in ameba and paramecium ___ vacuole
3. NUCLEUS&mdashcontrol center of the cell
4. EYESPOT&mdashin euglena, used to detect light
5. SPIROGYRA&mdashhas a spiral shaped chloroplast
8. PROTISTA&mdashKingdom that includes ameba and paramecium
10. FLAGELLA&mdashtail-like structure that functions in movement
12. UNICELLULAR&mdashorganism that has only one cell
14. VOLVOX&mdasha colonial algae
18. EUKARYOTE&mdashany organism that has a nucleus
19. PAREMECIUM&mdashprotist that is shaped like a shoe and uses cilia to move
20. AUTOTROPH&mdashorganism that can make its own food
21. PLASMODIUM&mdashthe name of the protist that causes malaria
23. MALARIA&mdashdisease carried by mosquitoes
Newly-Discovered Protists Add New Branch to Tree of Eukaryotic Life
A team of researchers from Dalhousie University, Canada, has identified two previously undescribed species of hemimastigotes — members of the extremely rare protist group Hemimastigophora. Through phylogenetic analysis, they found that hemimastigotes represent a previously unrecognized supergroup of eukaryotes. The findings are published in the journal Nature.
Hemimastix kukwesjijk. Image credit: Lax et al, doi: 10.1038/s41586-018-0708-8.
“This discovery literally redraws our branch of the Tree of Life at one of its deepest points,” said Dalhousie University’s Professor Alastair Simpson, lead author of the study.
“It opens a new door to understanding the evolution of complex cells — and their ancient origins — back well before animals and plants emerged on Earth.”
First observed in the 19th century, hemimastigotes are free-living eukaryotic protists with two rows of flagella and a unique cell architecture.
“Eukaryotic means the species have complex cells like humans and protist means the species are not animals, plants or fungi,” Professor Simpson and co-authors said.
“Like most protists, they are unicellular. Their flagella are long hair-like structures that allow these organisms to move, and also help them to capture other microbes, which they consume as prey.”
Hemimastix kukwesjijk: general view of cell. Scale bar – 5 μm. Image credit: Lax et al, doi: 10.1038/s41586-018-0708-8.
The team isolated to two new species of hemimastigotes — Hemimastix kukwesjijk and a yet-to-be-named species of the genus Spironema — from a soil sample collected from a region near Halifax, Nova Scotia, Canada.
“It was clear from our analyses that hemimastigotes didn’t belong to any known kingdom-level group, or even to a known ‘super-group’ of several kingdoms together, like the one that includes both animals and fungi,” Professor Simpson said.
“This one little collection of organisms is a whole new group at that level, all on its own. It’s a branch of the Tree of Life that has been separate for a very long time, perhaps more than a billion years, and we had no information on it whatsoever.”
The team’s results are vital for evolutionary biologists striving to piece together how the complex cells of animals, plants, fungi, algae and protozoa have evolved over the last 1-2 billion years.
Further, ecologists around the world studying the hugely important roles of microbes on the planet will now be able to identify hemimastigotes in their genetic datasets this biodiversity would have passed as unidentified until now.
“Researchers that study the microbial ecology of the ocean, lakes and soils will now be able to detect hemimastigotes in genetic samples pulled from these environments, giving a better understanding of what is actually there, and, potentially, how different microbes are interacting,” Professor Simpson said.
“That such a distinct form of life could be hiding literally under our feet is a sharp reminder about how little we still know about the diversity of life on Earth.”
Gordon Lax et al. Hemimastigophora is a novel supra-kingdom-level lineage of eukaryotes. Nature, published online November 14, 2018 doi: 10.1038/s41586-018-0708-8
Biology - A Panorama of Life
God is ordered, and His Creation reflects this order. Man has always sought to understand this order, and one of the ways we understand it is to classify it. In seeking to find some order in the living world, scientists looked to classify all living things into KINGDOMS. When man first began to classify living things, only two Kingdoms were used - PLANTS and ANIMALS. (** HISTORY NOTE ** Aristotle classified animal species, Carol Linnaeus is responsible for our modern nomenclature, and classified living things into two kingdoms - plant and animal)
Read Chapter 4 in Biology: Inquiry Into Life as a background, recognizing that at the time of this writing (1961) scientists recognized only two kingdoms, plant and animal.
As man began to understand living things with more detail, further nuances and distinctions began to be understood, and thus the need for more Kingdoms became apparent so that living things could be more accurately classified. There are now SIX KINGDOMS:
- - read and narrate (great overview of the six kingdoms). - print the chart provided and complete the task as written. - read and narrate. Be prepared to list the different taxa from Kingdom to Species IN ORDER - read and narrate.
And note to self. the "Kingdoms of Life- A Webquest for High School Biology" doesn't work for some reason.
Eubacteria are also single-celled bacterial organisms. This kingdom makes up most of the bacteria in the world. Eubacteria are very common and well-known to us as parasites like Streptococci which causes strep throat. However, these bacteria also help produce many antibiotics, vitamins and yogurt.
The Fungi kingdom is recognizable to us as mushrooms, molds, mildews and yeasts. Unlike the organisms in the Archaebacteria and Eubacteria kingdoms, Fungi are multi-celled organisms. Early scientists classified mushrooms and other fungi in the Plant kingdom but they do not produce their own food as plants do.
Characteristics of Monerans
Some monerans are autotrophic, making their own food through either chemosynthesis, like nitrifying bacteria in the nitrogen cycle, or through photosynthesis, like purple sulfur bacteria. Others are heterotrophic, either existing as saprophytic decomposers that feed on dead organic matter found in the soil, or as parasitic bacteria that acquire food from a living host, usually causing it harm in the process.
Organisms in the Monera kingdom can have different means of mobility, such as movement by using the flagella, as in the diagram above, to propel themselves through liquids, axial filaments to rotate, or by secreting slime to glide.
Most organisms in the Monera kingdom reproduce asexually through binary fission, which does not allow for much genetic diversity, since each daughter cell produced receives genetic information that is identical to the parent’s.
Certain organisms in the Monera kingdom can surround themselves by a capsule as a means of defense from adverse conditions and threats, such as phagocytosis by white blood cells, and desiccation. The cell becomes coated and partially dehydrated, turning into an endospore, which a dormant phase. When conditions become favorable again, the endospore then returns to being an active cell.
Methods of Reproduction in Protists (With Diagram)
It involves only one parent. All the young ones produced asexually have the same genetic constitution as that of the parent and are called clones.
Asexual reproduction can occur in the following ways:
It is the division of the parent body into two equal daughter individuals by mitosis. Examples: Amoeba, Euglena and Paramecium.
It is the division of the parent organism into several daughter individuals. Examples: Amoeba and Plasmodium.
It is the division of the multinucleate protist into two or more multinucleate offspring by the division of cytoplasm without nuclear division. It occurs in Opalina.
In some protists spores are formed for asexual reproduction. Spores have some sort of covering to withstand un-favourable conditions. On germination, each spore gives rise to a new individual. Example: Slime moulds.
In budding a small outgrowth develops from the parent body which separates and develops into a new individual. Example: Arcella (a sarcodine)
Method # 2. Sexual Reproduction:
It originated in protists. Sexual reproduction involves two fundamental processes meiosis that reduces the number of chromosomes from 2n to in and fertilization or fusion of two in gametes to form a 2n zygote (fertilized egg).
Meiosis is essential in sexual reproduction since it reduces the chromosome number to half in gametes so that after fertiliza­tion the number of chromosomes is kept constant in a species.
There are two methods of sexual reproduction:
It is complete fusion of two gametes to produce diploid zygotes.
Syngamy is of three types:
(i) Isogamy (two fusing gametes are similar e.g., Monocystis),
(ii) Anisogamy (two fusing gametes are dissimilar, e.g., Ceratium) and
(iii) Oogamy (large non-motile ga­metes are fertilized by smaller motile gametes, e.g., Plasmodium).
It is tempo­rary union of two individuals to exchange their haploid pronuclear to from a zygote nucleus. Each individual with zygote nucleus produces daugh­ter invidious by binary fission. It occurs in Paramecium.