Dictyostelium discoideum is an amoeba in the class Dictyostelia which is a group of cellular slime molds, also known as social amoebae. Their life cycle begins when they hatch from spores into myxamoebae. In this stage they are unicellular amoebae that reproduce by mitosis. Mainly found in soil these amoebae have a very short life cycle, only 24 hours long. Dictyostelium discoideum have 3 methods of reproduction; mitosis, sexual reproduction, and asexual reproduction. The first method is carried out while the cell is in its unicellular form. The second mode occurs when cells of opposite mating types fuse together creating a macrocyst that forms a zygote that engulfs surrounding bacteria and as it germinates, haploid myxamoebae are released. …show more content…
The amoebae feed on bacteria that secrete folic acid which attracts them. When the supply of bacteria runs out, the amoebae aggregate to form a multicellular fruiting body composed of a stalk and a spore containing sorus. This aggregation begins with the secretion of Cyclic AMP (cAMP) by a few cells which attracts other amoebae to them. They clump together and form what is called a Dictyostelium discoideum slug with anywhere from 100 to 2,000,000 amoebae in it that has motility due to a cellulose sheath secreted by the cells. It migrates towards light and heat, meaning the surface of the soil and once it is there the cells begin to differentiate into pre-stalk and pre-spore cells. The stalks grow upwards as high as they can to spread spores as far as possible to a more favorable environment, one with more bacteria. The farther the spores travel, the more likely they are to find a bacteria rich location. Genetically Dictyostelium discoideum has 6 chromosomes and is closely related to higher metazoans (a subkingdom of multicellular animals with differentiated cell types as well as usually a digestive tract and nervous system) which makes it a good candidate for genetic
In reproduction, the female produces clusters of eggs that she carries in one or two egg sacs that are attached to her abdomen. Once hatched, The T. Californium’ life cycle has quite a few stages. The first being six naupliar (young) stages lasting 4 – 10 days. Next come the 6-copepodite stages (7-14 days for the first 5 stages) ending in the last stage where T.californicus is a sexually mature adult. Adults then live from 40 – 90 days after the stages are complete (Rickets and Calvin 1985).
The life cycle of Naegleria fowleri includes three different stages: amoeboid trophozoites, flagellates, and cysts; due to the transitory nature of the microbe and the specific forms that it can take, it is frequently referred to as an amoeboflagellate. Despite its abilities to take on various forms, the amoeboid trophozoite is the only infective stage of the microbe and it requires favorable environmental ...
The Sacculina carsini, or parasitic barnacle, makes it’s host a green crab, also known as the Carcinus maenas. The parasite in this relationship changes the host’s behavior. It also enables itself to survive, spread and continue this cycle. As talked about in “The Parasitic Sacculina That Bends Its Host to Its Own Will”, when a female barnacle is still in its larval stage, it finds a crab host, and it locates a certain joint in the host’s shell. When there, the parasitic barnacle sheds her outer shell and puts herself inside the crab. Once she is inside, she is in a slug-like form. She creates a root system of tendrils, which extend throughout the abdomen of the crab. The root system takes over the crab’s intestine, diverticulae and surrounds the stomach. This
Sabellaria cementarium belongs to the phylum Annelids and is an invertebrate polychaete species. They are found in small clumps at the rocky bottoms of the sea floor where they use the rich source of natural phytoplankton as their primary diet (Qian and Chia, 1990). The tube-like worms can behave social and form extensive reefs or independently build hollow tubes in to the sandstone (pawlik and Chia, 1991). Embryos form a polar lobe that is absorbed in to the blastomeres at the end of division. Larval development and movement follows shortly after the 14-15 hour fertilization period where spiral cleaving of the fertilized oocytes appears (Render, 1983). Much is still not known about the invertebrate worm in their natural niche.
The gametophytes used in this experiment are of C-ferns. They tend to mature and produce spores at temperature of 28oC and conditions of high humidity. The spores that germinate first are hermaphrodites. Hermaphrodites tend to produce a pheromone called antheridiogen. It is this pheromone that causes later germinating spores to become male.
Treponema pallidum 2 Introduction Treponema pallidum is a Gram-negative bacterium that has a spiral shape (1). They are about 6 to 20um in length and 18-20um in diameter (1). Treponema pallidum can only survive within a host which makes them obligate internal parasites, meaning that outside a host this organism will die due to the absence of nutrients, exposure to oxygen and heat. Also, since this organism can’t be grown on a culture medium, animal models are used to study T. pallidum (1). Treponema pallidum bacteria consist of an inner and outer membrane with a thin peptidoglycan cell wall lacking liposaccharides (1).
N fowleri has three stages of their cycle. In the amoeboid trophozoite stage, they are infectious and measure 10-35 µm long. The trophozoite transforms to a non-feeding flagellate when food sources are limited. Flagellates are motile and measure 10-20 µm in length. The amoeba or flagellate will form a cyst, the dormant stage, if the environment is too cold and not conducive to continued feeding and growth. When the organism is in the cyst stage, it has a single layered wall and only one nucleus. The cyst measures 7-1...
These DIBELS screening assessments were developed to help educators identify struggling, at-risk readers, so that appropriate types and levels of support can be implemented within the school system. They were designed to support efforts at the primary grade levels (K-6th) to prevent reading struggles as the learn progress through the school system. Furthermore, this test was to aid in the elimination in remediation lessons inside of the classroom.
Sordaria fimicola is a species of microscopic fungus that is an Ascomycete and are used to test for genetic variation in the lab setting (Sordaria fimicola: A Fungus used in Genetics, Volk). These organisms are what are called model organisms, or species that has been widely studied usually because it is easy to maintain and breed in a laboratory setting and has particular experimental advantages (Sordaria fimicola, Volk). S. fimicola, because it is in the Ascomycota phylum, have a distinguishing reproductive structure called the ascus, which is surrounded by the perithecium. This cylindrical sac-like structure houses 8 haploid spores; created through meiosis to produce 4 haploid spores and then mitosis to make 8 (Lab Manual, pg. 59-68). Based on the genotype they will vary in order and color. There are 3 different ratios that can arise from the 8 ascospores: 4:4, 2:2:2:2, and 2:4:2 (black/wild type and tan coloration). The 4:4 ratio suggests that no crossing over had occurred because there is no difference in order of the color parents that were mated. The two other ratios suggest genetic recombination, or crossing over, because of the
Meiosis, also called reduction division, is a distinct type of cell division that is essential for sexual reproduction to occur. It is one in which two successive divisions of diploid cell occur thereby producing four genetically different haploid daughter cells, also called gametes, each with half the number of chromosomes and thus, half the total amount of genetic material as compared to the amount before meiosis began. Interphase precedes meiosis and thus, paves the way for meiosis to eventuate as the cell’s DNA replicates in the S phase yielding corresponding, identical chromosomes. Interphase sparks the marvelous process of meiosis that allows variation to transpire within the organisms it occurs, hence, giving rise to millions of organisms with unique aspects unlike any other on Earth. Because meiosis is a form of sexual reproduction itself, it is the means through which gametes are produced, each with a reduced number of chromosomes, so that when two gametes fuse during fertilization, not only do they form a diploid zygote with 46 chromosomes, but also have manifested differing features due to the rearrangement (crossing-over) of chromosomes.
Arthropods are animals belonging to the phylum Arthropoda, which is the largest of all phyla in the Animal Kingdom, with more than one million species, making them almost 80% of the whole kingdom. These include insects, arachnids, crustaceans and many more, most of which are quite small, the biggest being the Japanese Spider Crab with a leg span of 3.5 meters and the smallest being the microscopic Plankton.
Bacteria are single celled microbes. Bacteria reproduce by binary fission. In this process, the bacterium, which is a single cell, divides into two identical daughter cells. Binary
Another would be that some species of the pennate diatoms are motile, meaning they are able to propel themselves in the water column. This helps them maintain a planktonic existence because they are able to stay at the top of the water column there there is more sunlight. Then there is the siliceous frustule, it is thought to have developed because it could help protect the diatom from grazers. Another thought for the siliceous frustule is that it could help capture light energy for photosynthesis, which would help them diatom because it needs photosynthesis to live. Those are some of the morphological adaptations that diatoms have evolved to help them maintain a planktonic existence.
Porifera is the most simplistic phylum under the kingdom Animalia. The sponges have no tissue layers, but instead an interior and exterior layer with a gelatinous middle layer that separates the two. They are the only phylum with asymmetrical symmetry. Throughout the advancing phyla it will be shown this trait is lost. Porifera lacks a proper digestive system, but a canal system allows the sponges to filter feed. Along the inside of a sponge, flagella pump water through the sponge’s body. This process brings in oxygen and other small organisms and then flows out the top of the sponge, the osculum, removing waste by diffusion. Sponges lack a circulatory system, as does many of the first couple of phyla. A coinciding factor could be their small size. A nervous system is also missing, but very basic nerve cells within the pores sense the water currents. Gas exchange occurs through these pores. Reproduction in sponges can be asexual by budding, gammation, or fragmentation. Some sponges can also have sexual reproduction occur as an egg gets released and fertilized in the open water by free floating sperm. After this stage they cling onto rock and begin their sessile, basic, life....