PROTOZOAN
I did not include the protozoa in the Animal Kingdom because they are included in a separate kingdom: the Kingdom Protista.
Protozoa are single-celled eukaryotic heterotrophic protists. Eukaryotic cells are possessing a nuclear membrane that contains the genetic material (DNA). Heterotrophic means you can not make their own food, should buy it already prepared.
Somewhat surprising is that the cell contains organelles protozoa with functions equivalent to those of the organs of the Metazoa (multicellular animals).
The kingdom Protista includes eukaryotes, unicellular or multicellular (forming colonies), heterotrophic (Protozoa ingest or absorbent as Mycetozoides), autotrophs (algae), or mixotrophic (which are both autotrophs and heterotrophs (eg, Euglena ). Most of them are mobile, but some sessile species.
As we can see, the meaning of "protist" is very complicated. For this reason, protists have been divided into five kingdoms "tentative" PROTOZOA
belong to the Kingdom Protista. They are eukaryotic, unicellular and heterotrophic. Many are motile. There are approximately 45,000 described species of protozoa. They can be found in water, where they play an important role in the food chain or in symbiosis with higher animals or other organisms.
can visit the following website to see photos and films on protozoa. Http://www.cellsalive.com/
Importance:
Contribute the fertility of the soil as organic matter decomposes.
operate in the natural control of microbial populations as they feed on various types of microorganisms.
Cause disease to humans and animals of domestic importance. Structure and function
possess organelles that are involved in the movement, nutrient uptake, excretion, osmoregulation, reproduction and protection. Locomotion
There are 3 types of organelles responsible for locomotion in protozoa:
pseudopodia are temporary extensions of cytoplasm, usually found in amoebas. These are also important to capture food.
flagella are elongated structures as drivers of body hair. These structures react to chemicals and touch. The internal structure of the flagellum is similar in all eukaryotes.
cilia are structures similar to flagella, but smaller. These organelles may cover the entire surface of the protozoan or be restricted to a particular region such as the oral region. In some agencies these cilia fuse into Cirris, which can function as legs. Food and digestion
autotrophic protozoa synthesize their own food through photosynthesis.
heterotrophic protozoa, on the other hand require organic substances pre formed the environment. Food holozoica
is ingestion of whole organisms or small particles of food. They have mechanisms for capturing food such as food and drinks cytosome ("mouth"). After ingestion of particles, they pass cavities called vacuoles degestivas food. The waste is removed by the citopigio. Excretion and osmoregulation
The organelle responsible for these functions in many protozoa in the contractile vacuole. Excretion of waste products can be carried out by the cell surface. In malaria can be seen that some of the symptoms are caused by waste products parasite that is excreted and accumulated in the infected human cell.
protective structures
Many of these structures prevent mechanical damage and protect the body from drying out, getting too much water and predators.
covers the surface are shells that consist of sand grains or other foreign particles. They may also consist of calcium carbonate or silica. Intracellular organelles
Tricocistos are used for prey capture and defense.
Movie ("pelicle") is a stronger cover the cell membrane which is stuck. This provides protection against chemicals, damage mechanical and water loss.
Lifecycle
This consists of protozoa trophozoites and cysts (cysts). The phase where protozoa carried out their main activity (nutrition and growth) is in the trophozoite stage. In this phase can not withstand the effects of different chemicals, food deficits, drastic changes in temperature, pH and other environmental factors. To counter these adverse factors are cysts or cysts.
The cystic stage is the life cycle of protozoa which is resistant to different environmental conditions. The cysts are metabolically dormant, or inactive. This phase is important for the dispersal of organisms. A protozoan pathogens such as dispersal is by means of cysts is Entamoeba histolytica, which causes amoebic dysentery. Forms of reproduction
ciliated protozoa are binucleate, have a macronucleus which regulates the metabolic functions and development and maintain the features visible. They also have a microkernel that regulates reproductive processes.
In asexual reproduction are:
1. Binary fission, which is the most common type of asexual reproduction.
2. Budding, where a new individual is formed, either on the surface or in the internal cavity.
3. Multiple fission, such reproduction involves the formation of multinucleated organisms that carry out the division.
In sexual reproduction are:
1. Syngamy, here you can see the union of 2 different sex cells resulting in a zygote.
2. Conjugation, which is characteristic of ciliated protozoa. The process involves the partial union of two ciliates, in which case the exchange of a pair of haploid micronuclei. Following the merger of these micronuclei are diploid micronuclei, which divide by mitosis giving rise to 2 identical diploid organelles.
3. Autogamy in this process, the micronucleus divides into 2 parts and then assembled to form a zygote. The protozoan divides to give rise to 2 cells, each with complete nuclear structures. Growing
Protozoa need moderate light, temperature 15 to 21 degrees C and pH neutral to slightly alkaline. If using an artificial medium, it may include rice, wheat grains, skim milk and lettuce. If a specific medium, containing glucose, protein, minerals and yeast extract. Some need as food organisms. On the other hand, the parasites are grown in tissue culture preparations. Classification
for classification takes into consideration: the method of obtaining food, the method reproduction, cellular organization, structure, biochemical analysis of nucleic acids and proteins and organelles of locomotion.
Kingdom Protista Phylum Ciliophora (ciliates Paramecium is an example) is characterized by the presence of thousands of cilia on its surface. These have the function of the movement and obtaining food. The ciliates are the most specialized, as they have organelles that perform vital functions. These are found in salt water to fresh. Some are free living while others are parasitic or commensal. Phylum
Sarcomastigophora
1. The subphylum Opalinata found in the intestines of toads. Possess cilia shaped organelles arranged in rows on the surface of your body. Some have two or more cores, but are not differentiated in micro-and macronucleus. This group is played by syngamy.
2. The subphylum Sarcodina these have pseudopodia used to move and capture food. This group is simple in structure when compared with ciliates and flagellates. They have few organelles and have no definite shape of the body. Found in all bodies of water. This phylum includes the foraminiferal group (with 18,000 species). Also here we find Entamoeba histolytica causes amoebic dysentery, the disease is spread through cysts in contaminated food and water.
3. The subphylum Mastigophora are protozoan flagellates in some stage of his life and mostly unicellular, they are free living, commensal, mutualistic or parasitic. Phylum Apicomplexa
Between group includes intra-and intercellular parasites of animals. It is distinguished by its unique arrangement microtubules, vacuoles and other organelles located at one end of the cell. This group does not have organelles of locomotion.
phylum Sporozoa are parasites and absorb nutrients from their hosts, some are intracellular. Others live in the body fluid or other organs. The adults do not have sporozoas organelles of locomotion. Examples are the causative agents of malaria and toxoplasmosis causing the latter cause la muerte patients with AIDS. El protozoan that causes toxoplasmosis is la encuentro en la excreta of them cats.
PLAYING BY PROTOZOA
SOLANGE Fishy
INTRODUCTION In the living room is the reproduction of an organism pre-existing bodies brothers. In the simplest cases of protozoa each cell through its division, can be used in the creation of new individuals who remain without parental organism.
Moreover, the essential aspect of the sexual activities of protozoa is the production of haploid gametes nuclei and subsequent merging to form a haploid zygotic nucleus.
Sexual reproduction in almost all metazoans is somewhat different. In such separation occurs in a germ line, whose eggs and sperm to ensure continuity of life, and a lineage whose somatic cells are mortal and do not participate in the reproductive process. Each type of gamete usually comes from two individuals (male and female), which often remain alive and produce gametes for other additional fertilizations.
Gametes are produced by two successive divisions of immature germ cells in which the number of chromosomes is reduced by half (haploid), seen in the nuclei of germ cells in adult diploid number. The result of the merger for syngamy or fertilization of haploid gametes or diploid zygote is an egg that will make a long series of cell divisions, accompanied by several changes in order to produce a young individual.
Although the union of haploid gametes occurs in at least some protozoa, the resulting diploid stage (zygotes) divide carries while playing. However, in metazoans the divisions of the zygote is an essential part of developing a new individual.
Many forms of reproduction in protozoa comprise a agamogonia or asexual reproduction, which is the fragmentation of the individual comprising one or more mitoses. The mitosis in protozoa is distinct from that in metazoans, because there is permanence of the nuclear membrane, no zone or else the existence of an intranuclear spindle.
The meiosis is a variation of their occurrence in the life cycles of different groups of protozoa in the number of chromosomes. Some have diploid nuclei and somatic cells of metazoa, others are haploid, as in the gametes of higher plants and animals, there are still those with polyploid nuclei, ie, they have three or more haploid sets of chromosomes, as is the case of most ciliate macronucleus. In metazoan chromosome reduction always precedes fertilization.
reproduction of protozoa, the subject of this text, but always involves the division of an organization holds several methods, which are described below. But before we do a brief presentation on the points of occurrence of meiosis in the life cycles of the same.
1. MEDIA AND CYCLES
the protozoa as well as many lower plants, meiosis can occur soon after fertilization, zygotic meiosis is that exists in various gregarines Coccidia (phylum Apicomplexa, class Sporozoa, genus Plasmodium), few Sarcodina, some intestinal flagellates and in certain protist affinities with vegetables, such as Volvox . This
meiosis usually occurs during the first two divisions of the zygote. In these cases the active phase of the life cycle, or a portion thereof, has the haploid number of chromosomes and such bodies are so called haplobiontes.
NÞFertilização 2NÞMeiose (formation of spores) N ˚
In many other protozoa the diploid number of chromosomes is most of the cycle, where meiosis is gametic. Are therefore comparable to the cycle of metazoans. In protozoa that meiosis results in gametes and nuclei occurs in opalinídeos and ciliates. The cycle is called diplobionte.
2NÞ Meiosis (N) fertilization 2NÞ
There is also a cycle called haplodiplobionte known in some formníferos. In it the haploid and diploid phases correspond to different generations are likely to present phenomena of asexual multiplication. Meiosis is executed during the last mitotic cycle of haploid pairings. N ˚
Meiosis Fertilization 2NÞ
2. METHODS OF REPRODUCTION
The protozoa multiply asexually more frequently, but regularly uses certain groups or under certain environmental conditions for mating, while others have complex cycles in which alternating stages of asexual multiplication and sexual reproduction. The ability to perform a sexual phase is restricted to ciliates, and apicomplexan taxa of flagellates and some Sarcodina.
The reproductive cycle of protozoa involves a period of growth followed by reproduction, growth of organisms resulting from its own and eventually reproduction. The period of individual growth ranges from several hours to several days or even several months, as occurs in the life cycles of certain foramníferos.
2.1. ASEXUAL REPRODUCTION
is the simpler process of multiplication, since starting from a single body that mitosis has formed another with the same genetic characteristics of the parental organism. If no mutations occur all the offspring will be comparable, thus constituting, clones.
There are the following methods: simple binary division
This type of reproduction is based bipartition in the cell body. Naked amoebae in there division plan, they simply assume a rounded shape and divide into two halves basically identical daughter cells receive directly the structure of the parent, just one of these individuals will be formed again, a contractile vacuole. Already in the testate amoebae there is considerable variability and its division often resembles the budding process (Fig. 1), as in Arcella. In these the protoplasm gradually spreads outward through the opening of the shell as a large pseudopodia, separating after mitosis. The body retains the generator shell and half the cytoplasm, while the other member of a secret new shell.
Figure 1. Binary division of Arcella.
the flagella body becomes constricted lengthwise and each individual has to differentiate a new flagellar apparatus.
Figure 2. Binary division of flagellates ciliates
In both types of nucleus (micronucleus and macro) are divided and the body is usually choked plasma (Fig. 3) across, each individual receives a pair of cores. Are needed as new distinctions: every half a second contractile vacuole and the daughter cell "later" a new cytostome, including specialized areas of cilia as the old cytostome moves to the body "before." The differentiation of new organelles begins within the first nuclear divisions and precedes the division of the cytoplasm. Some ciliates, eg, Colpoda, fall within cysts, initially in two brothers who form the new division after four ciliates, which are released when there is rupture of the cyst wall.
An exception to the transverse plane of division in ciliate Vorticella occurs, and this longitudinal study.
Figure 3. Binary division of Paramecium.
Plasmotomia: A variant of binary fission occurs in some protozoa, multicellular organisms that normally fall into more than two new, smaller bodies, and where the division regardless of cytoplasmic nuclear division. As occurs in certain Sarcodina Pelomyxa in opalinates, among others. Bodies siblings may differ in both size and number of cores they receive.
Division Multiple or fission (schizogony =)
Division Multiple follows the repeated mitoses, in some groups of protozoa, the nuclear division is followed immediately by citodierese. Then follows the accumulation many nuclei, perhaps thousands, before they start differentiating daughter cells. When this process begins to form almost simultaneously many organisms children. Then the cytoplasm divides into as much territory as the daughter nuclei, isolating elements or unicellular esquizozoítos. Occurs in protozoan parasites (Apicomplexa, Microspora, and Ascetospora Mixozoa) and some free-living species (and foramníferos "radiolaria").
Among the free-living protozoa, the foramníferos are distinct, because the sexual phase is a regular part of life cycle, alternating with a sexual phase
Figure 4 represents the complex life cycle of Plasmodium, where there are two phases - sexual and asexual, the schizogony occurs in liver cells and blood of humans.
Figure 4. Life cycle of Plasmodium.
Budding is a form of fission in the course of which the cell can only be affected by maternal reproductive process. In a simple bud suctório the ciliated father, sedentary, saves your feeder device, while performing nuclear division and is produced a terminal or lateral bud that will develop into larva becoming ciliated. In other cases, the bud and there are multiple simultaneous production from 4 to 12 larvae (In Ephelota), although in other suctórios, Acineta for example, the larva can arise by sprouting from the bottom of a matrix cavity formed by invagination of the body surface. In some ciliates, ie the order Apostomatida there are cases of formation of linear chains formed by budding ciliates.
ciliated organisms resulting from budding, swim freely until they settled on a substrate, they lose the cilia and tentacles develop fixator and peduncle feeders.
2.2. Sexual
free living protozoa usually resort to sexual reproduction when environmental conditions become adverse, because when environmental factors and food availability are favorable, asexual reproduction is.
Based on surface features are recognized some varieties of sexual activities in protozoa:
- - syngamy OR copulation, ie, the complete union of two haploid cells (gametes). In primitive forms, there is isogamy morphological, ie similarity of the two gametes. From it comes the anisogamy in which microgametes mobile (the male sex cells) join with macrogametas (female sex cells) properties, in most cases.
- - CONJUGATION: ie transient partial union of two individuals, in which haploid nuclei are exchanged each other so that, following completion of the separation, the nuclei of ex-conjugants have a new chromosomal trim combination. The combination is found only in ciliate protozoa more highly differentiated and richer in cytoplasmic differentiation. The cycle is diplobionte.
Two ciliates, in most cases with the same form, is to each other by the oral region, there is formed a cytoplasmic bridge.
Figure 5. Diagram of conjugation in ciliates
After marriage the cytostome, the macronucleus each became disorganized and disappears, while the micronucleus undergoes two successive divisions, namely meiosis.
- Of the four resulting nuclei, and the last three degenerate splits once again, the final two
nuclei are called Pronuclear: male and female.
- The male pronuclei migrate toward each other cell of your partner and
pronuclei unite with the female who had remained in place. The core
resulting merged in each cell is a zygote (syncarion) where the diploid number of chromosomes is restored
.
- The cells separate and each divides three times, producing eight nuclei
children.
- The first two divisions are meiotic
- From 8 cores, 4 increase in size until it turned into so many
macronucleus
- One is being the micronucleus and the other disappear.
- Here are two normal divisions of the micronucleus and the entire cell (but without
multiplication of the macronucleus), resulting in the production end of the 4 ciliates
from one of two ex-conjugants, with a macronucleus and a micronucleus each.
partners together are hermaphrodites, they provide gametic nuclei of two types, which behave differently. Paramecia, but only when they belong to combine different but compatible types of pairing (Matingtypes). Before the conjunction is no emission of chemical signals by some ciliates, but in others, such as Paramecium, the chemical remains on the cell surface which expresses the response when the ciliates make physical contact.
These genes relate to the biochemical qualities of the lashes. In this case, the different types of pairing are determined from two alternatives for action loci of genes, so that a single individual only one locus is active.
In some species of Paramecium there is, in certain environmental conditions, or autogamous selfing: an unrelated partner pairing, meiosis takes place, and all subsequent changes, such as a combination "normal." The migratory and stationary nuclei of an individual flock then straight back in the zygotic micronucleus from which derive the new macro and micronuclei. Through this process of autogamy formed isozigóticos individuals and clones that are homozygous for all pairs de alelos. Este processo ocorre também em certos flagelados intestinais de insetos que se nutrem de madeira.
CITOGAMIA : é um caso misto, semelhante à conjugação, pelo fato de dois indivíduos se ligarem, mas onde não há ponte citoplasmática e nem troca de micronúcleo. O processo é AUTOGÂMICO.
Os ciliados denominados suctórios praticam um processo que é uma modificação da conjugação, pois os conjugantes têm aparência distinta. Quando um microconjugante localiza um macroconjugante eles se fundem. Isto é um tanto diferente do que ocorre na associação temporária de muitos ciliados.
Qual o real significado da conjugação and their transformation between intracellular protozoa? According Woodreff, 1925 (in Manwell, 1968 p.211) the "combination has a direct value for survival, and produce a profound stimulation of metabolic activities of the cell, which is expressed in the play." Phenomena such as sexual conjugation
play another key role, ensuring the continued existence of species. Like other forms of sexual reproduction, it results in a genetically diverse population better able to survive the inevitable changes in any environment.
sporogony
is a special case of reproduction Sexual: After syngamy, the zygote undergoes repeated nuclear divisions, and only after they are finalized, you start playing the daughter cells. In this second phase of the multiplicative process, the sporogony resembles schizogony. In
Apicomplexa where sporogony alternates with each schizogony in the life cycle of the parasite sporogony often lead to the formation of elements protected by a sturdy wrap - Spozoites - designed to withstand the unfavorable external environment during transmission parasitic infection. CONCLUSION
then we saw that in many protozoa, sex appears occasionally, often caused by external actions and each individual is able to effect fertilization or go through changes (maturation) that lead to fertilization capacity. But in many species, certain individuals may only multiply asexually, while others are designed in the form of gametes, the sexual union. In a kind toggles, often in a given cycle, generations of individuals with each other that are different from their mode of reproduction are often also in their morphology. Thus, a development cycle that Gerace abrange uma série, de novo ao mesmo conduz state. Denote this by alternating processo Gerace; em parasites, prune to be linked to uma Mudanças of Hospedeiras, we mainly Apicomplexa, par example, we give agents malaria.
Osmotic pressure is that which would be necessary to stop the flow of water through the semipermeable membrane. When considered as semi-permeable to the plasma membrane, cells in multicellular organisms must remain in osmotic equilibrium with tissue fluids that bathe.
Meiosis I (first division of meiosis) is the most important because it occurs during chromosome synapsis, recombination and disjunction or segregation.
or prophase I: the chromatin condensation is followed by very close matching of homologous chromosomes with the synaptonemal complex formation and the formation of chiasmata (cross). These chiasmata are light microscopy and persist until metaphase I. Involve cross between two homologous chromatids (each from a homologous chromosome, while the other two do not work). Indicate that there has been a reciprocal recombination and there is at least one chiasma between each pair counterparts. You need a proper synaptonemal complex formation and presence of at least one chiasma between the counterparts to ensure normal disjunction.
or Metaphase I, homologous chromosomes are arranged aligned in the equatorial plane.
or Anaphase I: Homologous pairs separate, the sister chromatids remain together.
or Telophase I: have formed two daughter cells, each containing only one chromosome of homologous pair.
Meiosis II (second division of meiosis): formation of gametes.
or prophase II: DNA is not replicated, and the transition between the two divisions is very fast, similar to an isolated G2 period.
or Metaphase II: the chromosomes are arranged in aligning the equatorial plane.
or anaphase II, centromeres divide and sister chromatids migrate separately to each pole.
or telophase II: cell division is complete. They have won four haploid daughter cells.
GENETIC CONSEQUENCES OF MEIOSIS
or reduction in the number of chromosomes from diploid to haploid.
or segregation of alleles in meiosis I or meiosis II.
or mixture of genetic material by random distribution of homologous (Mendel's second law).
or recombination that provides additional mixing of genetic material.
ciliates found in the conjugation process - sexual reproduction in which only the nuclei fuse. Movies and join the macrocores disintegrate. Micronuclei undergo meyoticas divisions and produce haploid pronuclei. A migratory pronucleus of each cell goes to the other and merge with the corresponding stationary pronucleus to form new diploid nuclei.
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