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From Wikipedia

Fission (biology)

In biology, fission is the subdivision of a body, population, or species into parts and the regeneration of those parts into separate individuals. Binary fission, or prokaryotic fission, is a form of asexual reproduction and cell division used by all prokaryotes, some protozoa, and some organelles within eukaryotic organisms. This process results in the reproduction of a living prokaryotic cell by division into two parts that each have the potential to grow to the size of the original cell.

Mitosis and cytokinesis are not the same as binary fission. To be specific, binary fission cannot be divided into prophase, metaphase, anaphase, and telophase because prokaryotes have no nucleus and no centromeres. The ability of some multicellular animals, such as echinoderms and flatworms, to regenerate two whole organisms after having been cut in half, is also not the same as binary fission. Neither is vegetative reproduction of plants.

Process

Binary fission begins with DNA replication. DNA replication starts from an origin of replication, which opens up into a replication bubble (note: prokaryotic DNA replication usually has only 1 origin of replication, whereas eukaryotes have multiple origins of replication). The replication bubble separates the DNA double strand, with each strand acting as template for synthesis of a daughter strand by semiconservative replication, until the entire prokaryotic DNA is duplicated.

Each circular DNA strand then attaches to the cell membrane. The cell elongates, causing the DNA to separate.

Cell division in bacteria is controlled by the FtsZ, a collection of about a dozen proteins that collect around the site of division. There, they direct assembly of the division septum. The cell wall and plasma membrane starts growing transversely from near the middle of the dividing cell. This separates the parent cell into two nearly equal daughter cells, each having a nuclear body.

The cell membrane then invaginates (grows inward) and splits the cell into two daughter cells, separated by a newly grown cell plate.

Use by eukaryotic organelles

The use of binary fission by Eukaryoticorganelles such as mitochondria, chloroplasts, and peroxisomes is not yet clear.


Binary asteroid

A binary asteroid is a system of two asteroids orbiting their common center of mass, in analogy with binary stars. 243 Ida was the first binary asteroid to be identified when the Galileo spacecraft did a flyby in 1993. Since then numerous binary asteroids have been detected.

When both binary asteroids are similar in size, they are sometimes called "binary companions", "double asteroids" or "doublet asteroids". A good example of a true binary companion is the 90 Antiope system. Binary asteroids with a small satellite, called a "moonlet", have been more commonly observed (see 22 Kalliope, 45 Eugenia, 87 Sylvia, 107 Camilla, 121 Hermione, 130 Elektra, 243 Ida, 283 Emma, 379 Huenna, etc.). They are also called high-size ratio binary asteroid systems.

Paired impact craters, such as the Clearwater Lakes in Canada, may have been formed by binary asteroids.

Several theories have been posited to explain the formation of binary asteroid systems. Recent work suggests that most of them have a significant macro-porosity (a "rubble-pile" interior). The satellite orbiting around large main-belt asteroids such as 22 Kalliope, 45 Eugenia or 87 Sylvia could have formed by disruption of a parent body after impact or fission after an oblique impact. Transneptunian binary asteroids may have formed during the formation of the solar system by mutual capture or three-body interaction. Near-Earth asteroids which orbit in the inner part of our solar system may have split by tidal disruption after a close encounter with a terrestrial planet. A possible explanation for the relatively greater occurrence of binary asteroids near or inside of Earth's orbit was described in the journal Nature (10 June 2008): this theory states that when solar energy (see YORP effect) spins a “rubble pile� asteroid to a sufficiently fast rate, material is thrown from the asteroid’s equator. This process also exposes fresh material at the poles of the asteroid.


Yeast

Yeasts are eukaryotic micro-organism s classified in the kingdom Fungi, with the 1,500 species currently described estimated to be only 1% of all yeast species. Most reproduce asexual ly by budding, although a few do so by binary fission. Yeasts are unicellular, although some species


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Question:

Answers:Advantage 1. Reproductive cycle is small 2. its a simple process without the involvement of 2 parents Disadvantage 1. no evolution occurs 2. the daughter is exact copies of the parent

Question:Whats the advantages and inconveniences of : Binary fission, Budding, Spore formation,Fragmentation, Vegetative reproduction

Answers:(1) Binary fission is the process by which prokaryotes divide into two identical daughter cells, which can eventually grow to the same size as the original parent cell. Such reproduction is characterized by exponential growth phases. A disadvantage is that there is little or no genetic variation, so habitat adaptation is not as rapid as would be expected with eukaryotic sexual reproduction. (2) Budding (also called burgeoning) is the formation of a new organism by the protrusion of part of another organism. This is very common in plants and fungi, but may be found in some animals as well, such as the Hydra. Usually, the protrusion stays attached to the primary organism for a while, before becoming free. The new organism is naturally genetically identical to the primary one (a clone), so, as with binary fission, there is not as much genetic variation in offspring as occurs with sexual reproduction. (3) Spore formation. A spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many plants, algae, fungi and some protozoans. Spores are usually haploid and unicellular and are produced by meiosis in the sporophyte. Once conditions are favorable, the spore can develop into a new organism using mitotic division, producing a multicellular gametophyte, which eventually goes on to produce gametes. Two gametes fuse to create a new sporophyte. This cycle is known as alternation of generations, but a better term is "biological life cycle", as there may be more than one phase and so it cannot be a direct alternation. Haploid spores produced by mitosis (known as mitospores) are used by many fungi for asexual reproduction. A chief difference between spores and seeds as dispersal units is that spores have very little stored food resources compared with seeds. Because spores contain so few nutrition stores, they are not as nurturing to a developing individual as a seed, egg, or placenta. (4) Fragmentation or Clonal Fragmentation is a form of asexual reproduction or cloning where an organism is split into fragments. The splitting may or may not be intentional. Each of these fragments develop into mature, fully grown individuals that are a clone of the original organism. If the organism is split any further the process is repeated. Fragmentation is caused by mitosis. Meiosis is not involved in fragmentation. Fragmentation is seen in many organisms such as molds, some annelid worms, and starfish. Binary fission of single-celled organisms such bacteria, protozoa and many algae is a type of fragmentation. Molds, yeast, and mushrooms, all of which are part of the Fungi kingdom, produce tiny filaments called hyphae. These hyphae obtain food and nutrients from the body of other organisms to grow and fertilize. Then a piece of hyphae breaks off and grows into a new individual and the cycle continues. As with other types of asexual reproduction, fragmentation does not provide any genetic variation in offspring, and does not allow for any hybridization or heterosis. Thus, as with all forms of asexual reproduction, adaptation to new environemental conditions is not as rapid as with sexual reproduction. (5) Vegetative reproduction is a type of asexual reproduction found in plants, and is also called vegetative propagation or vegetative multiplication. It is a process by which new plant "individuals" arise or are obtained without production of seeds or spores. It is both a natural process in many plant species (as well as non-plant organisms such as bacteria and fungi) and one used or encouraged by horticulturists to obtain quantities of economically valuable plants. As with other types of asexual reproduction, vegetative reproduction does not provide any genetic variation in offspring, and does not allow for any hybridization or heterosis. Thus, as with all forms of asexual reproduction, adaptation to new environemental conditions is not as rapid as with sexual reproduction.

Question:1]how is half life used to determine the amount of a radioisotope remaining at a given time? 2]give two examples of equations for the synthesis of transuranium elements by transmutation? 3]explain the process of transmutation. write at least tree nuclear equations to illustrate your answer 4]The mass of cobalt-60 in a sample is found to have decreased from 0.800g to .200g in a period of 10.5 yrs. From this informaiton, calculate the half-life of cobalt-60. 5]describe how a nuclear fission power plant operates. 6]explain what happens in a nuclear chain reaction. 7] identify 2 types of nuclear waste produced by nuclear power plants. 8]assuming technical problems could be overcome, what are some advantages to producing electricity in a fusion reactor?

Answers:Do you plan to do any of this work yourself, or should we do your homework for you?

Question:1.How and what did Dr. Mayer discover specifically in 1883? 2.What did Ivanowsky conclude that built on Mayer s work? 3.What logic did Beijerinck use to lead to the idea of a virus? 4.How was the existence of a virus finally confirmed and by whom? 5.How small are viruses? 6.What kind of nucleic acids are the viral genomes made of? 7.What is the name for a protein shell enclosing the viral genome? 8.What are the subunits of capsids? 9.What are viral envelopes and what is their function? 10. Where are the most complex capsids found? 11. Define host range. 12. List the full steps of the simplified viral reproductive cycle. 13. What is the phage reproductive cycle that culminates in the death of the host cell? 14. What kind of phage only reproduces by a lytic cycle? 15. How do bacteria defend themselves against phages? 16. What are the steps of the lytic cycle of a T4 phage? 17. What is the phage reproductive cycle that replicates the phage genome without destroying the host? 18. What are phages called that care capable of using both modes of reproduction? 19. What is a prophage? 20. What is an example of the interaction between a prophage and a bacterium? 21. What is the use of a viral envelope in animal viruses? 22. Does this reproductive cycle kill the host cell? 23. What are retroviruses and how do they use reverse transcriptase? 24. Describe the reproductive cycle of an enveloped RNA virus. 25. Describe the reproductive cycle of HIV, a retrovirus. 26. Is it believed that viruses evolved before or after the first cells appeared and what evidence is used to support the idea? 27. What are vaccines? 28.What are the three processes that contribute to the emergence of viral diseases? 29. List and explain the two major routes that plant viruses are spread. 30. What are viroids? 31. Define prions. 32. What is the main component of most bacterial genomes? 33. How is the DNA arranged in the nucleoid region of the bacterial genome? 34. What is a plasmid? 35. Describe the process of binary fission. 36. Why do mutations make such a large contribution to bacterial genetic variation as compared to humans? 37. Explain the experiment and the results that demonstrated evidence of genetic recombination in bacteria. 38. What is the process of alteration of a bacterial cell s genotype by the uptake of naked, foreign DNA from the surrounding environment? 39. What famous experiment in the previous unit described this process? 40. Define transduction. 41. List the generalized steps of transduction. 42. What is the process of direct transfer of genetic material between two bacterial cells that are temporarily joined? 43. What structure joins them? 44. What generally must be present for the sex pili to donate DNA during conjugation? 45. What is special about the F plasmid? 46. What is an episome? 47. What are R plasmids and why are these a problem to humans? 48. How does this relate to natural selection? 49. Define transposable elements. 50. Do transposable elements exist independently? 51. What is a common name for transposable elements? 52. What is the name for the simplest transposable elements? 53. What is the name for transposable elements that are longer and more complex than insertion sequences? 54. What is an example of the benefit to bacteria of these transposable elements? 55. What are the two ways that metabolic control can occur within bacteria? 56. What is the key advantage of grouping genes of related function in to one transcription unit? 57. What is this switch called? 58. Where is an operator positioned? 59. What does the operator control? 60. What is the name for the operator, promoter, and the genes they control? 61. What can happen if the trp operan is turned on ? 62. What turns the switch off? 63. How does a repressor work? 64. What gene controls the making of the trp repressor protein? 65. What are the two states that the operator vacillates (switches between)? 66. How is the trp repressor protein and allosteric protein? 67. Define corepressor. 68. What are the two methods of negative gene regulation? 69. Why is the trp operan considered repressible? 70. What is the definition of an inducible operan? 71. What does the inducer do? 72.Why are repressible enzymes generally associated with anabolic pathways and how is this an advantage to the organism? 73. How does positive gene regulation work? 74. We stated in the beginning of the year that negative feedback has an on/off switch and positive feedback can only amplify the response how does this statement connect wit

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From Youtube

Protozoa Ciliate Division by Equal Binary Fission in HD :This video shows a protozoan ciliate in the process of dividing. This ciliate protozoan was found in amongst a floating algal mass floating on the surface of a fresh water pond in the Bitterroot Valley of western Montana. Note the cilia beating at the edge of the organism. I am not an expert in identifying protozoa, so if anyone can pin down the Genus and species, it would be nice to know. Comments on the video are welcome.