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Cellular division process
Cellular division process
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Cell division may happen by either mitosis or meiosis, depending on what type of cell is invovled. Mitosis is a process by which a cell divides to form two daughter cells. They each have the same exact number and kind of chromosomes as the parent cell. Meiosis occurs in the primary sex cells leading to the formation of viable egg and sperm cells. They reduce the number of chromosomes to half in each gamete so that when they are getting furtilized, the species chromosome number is kept even.
Mitosis happens in the reproduction of unicellular organisms and in the addition of cells to a tissue or organ in a multicellular organism.
There are four stages of mitosis. The first stage is the prophase. In this stage the chromosomes become shorter and thicker and they each consist of two chromatids. The nuclear membrane begins to disintegrate. The centrioles in animal cells, fungi, algae and some other ferns double and a pair move toward each pole and the chromosomes begin to move toward the equator of the cell.
The second stage is called the metaphase. In this stage the centrioles move to the poles. The chromosomes line up at the equator of the spindle and the spindle fibers are attached to the centromeres connecting them to the poles of the spindle.
The third stage is called the anaphase. By this time, the centromeres split apart. The chromatid pairs of each chromosome separate from each other and they move quickly in opposite directions, one toward each pole.
The last stage is cal...
During interphase, the cells in both animals and bacteria carry out their division general functions according to the type of their cells. Unlike in plants, a preprophase group of cytoskeletal proteins emerge at a future location of the cell plate. At prophase stage, duplicated chromosomes compress in a way that can be seen with the help of a microscope. On the other hand, the mitotic spindle is formed at one side of nucleus, whereas in plants, spindle is formed around the nucleus. During prometaphase in animals and bacteria, the nuclear membrane disappears, the chromosomes attach themselves to mictotubules and start to move. In plants, however, the preprophase group dissolves while at metaphase stage, the chromosomes get aligned at the core of the cell. At anaphase, there are fewer differences between animals and plants. The chromosomes shift apart towards the both par...
Trisomy 13 or Patau Syndrome” Trisomy 13 is a genetic disorder found in babies. It is also called Patau syndrome in honor of the physician who first described it, Krause Palau. Trisomy 13 is a genetic disorder in which there is three copies of chromosomes on Chromosome 13. Patau first described the syndrome and its involvement with trisomy in 1960. It is sometimes called Bartholin-Patau syndrome, named in part for Thomas Bartholin, a French physician who described an infant with the syndrome in 1656.
Each cell contains the same genetic code as the parent cell, it is able to do this because it has copied it’s own chromosomes prior to cell death. division. The. Meiosis consists of two divisions whilst mitosis is followed. in one division; both these processes involve the stages of interphase, prophase, metaphase, anaphase, and telophase.
Precise chromosomal DNA replication during S phase of the cell cycle is a crucial factor in the proper maintenance of the genome from generation to generation. The current “once-per-cell-cycle” model of eukaryotic chromosome duplication describes a highly coordinated process by which temporally regulated replicon clusters are sequentially activated and subsequently united to form two semi-conserved copies of the genome. Replicon clusters, or replication domains, are comprised of individual replication units that are synchronously activated at predetermined points during S phase. Bi-directional replication within each replicon is initiated at periodic AT-rich origins along each chromosome. Origins are not characterized by any specific nucleotide sequence, but rather the spatial arrangement of origin replication complexes (ORCs). Given the duration of the S phase and replication fork rate, adjacent origins must be appropriately spaced to ensure the complete replication of each replicon. Chromatin arrangement by the nuclear matrix may be the underpinning factor responsible for ORC positioning. The six subunit ORC binds to origins of replication in an ATP-dependent manner during late telophase and early G1. In yeast, each replication domain simply contains a single ORC binding site. However, more complex origins are characterized by an initiation zone where DNA synthesis may begin at numerous locations. A single round of DNA synthesis at each activated origin is achieved by “lic...
Gender stereotypes have existed since the beginning of modern man. We've all heard them before; male dominance and female weakness, a controlled male and a flustered female, aggression and passion, and many others that all basically boil down to the same thing. Emily Martin, in her essay entitled The Egg and the Sperm, takes this problem of gender stereotype to a new and much more serious level. As an anthropologist, Martin is concerned with the socio-cultural impacts on many different aspects of everyday life, including biology. In doing her research for this article, Martin was trying to uncover suspicions she had about socio-cultural gender stereotypes, and the affects they had on the diction used to describe egg and sperm interactions in numerous biology books and research reports.
Hats off to bacteria! This article summarizes that bacteria are good for our body and help us function a lot better. Bacteria live in our guts, in our mouths, and on our skin. Overuse of antibiotics has disturbed the bacterial ecosystem, possibly so much that it is irreversible. In 1999 Lawrence Brandt a professor of medicine and surgery at the Albert Einstein College of medicine had success when trying to help a patient combat diarrhea induced by clostridium difficile. A patient developed diarrhea after taking a course of antibiotics for sinusitis; nothing could shake her C.difficile infection. Brandt reasoned the initial antibiotic treatment had killed gut bacteria that promote digestive health; not knowing which strain to replace, he transplanted stool form her husband. That night she reported marked improvement- for the first time in six months. This procedure has helped patients, but hopefully in the future doctors will be able to administer the particular strain of bacteria that is needed. 99% of the bacteria we harbor are resistant to culture in the lab. It was this impossible to study bacteria until the last decade or so, when DNA sequencing techniques allowed researchers to obtain gene sequences from as little as one bacterial cell. With this researchers found that bacteria cells in our bodies outnumber our human cells. Bacterial exposure throughout our lifetime is needed for our wellbeing, thinking, and functioning, contributing to conditions such as diabetes, obesity, allergies, asthma, and atherosclerosis, as well as to anxiety and mood and cognition disorders. These conditions have become more prominent because of our obsession with sanitation has eliminated the exposure to bacteria humans used to routinely get throu...
A tort is wrongful interference against a person or property, other than breaches of contract, for which the courts can rectify through legal action. The reform effort is aimed at reducing the number of unnecessary lawsuits that burden the court system while still allowing injured parties compensation when they’ve been wronged. This latest effort at tort reform has given rise to the same spirited rhetoric that might be found in a courtroom.
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.
A chromosome is made up of two identical structures called chromatids. The process of nuclear division is called interphase; each DNA molecule in a nucleus makes an identical copy of itself. Each copy is contained in the chromatid and a characteristic narrow region called the centromere holds the two chromatids together. The centromere can be found anywhere along a chromosome but the position is the characteristic for a particular chromosome. Each Chromatid contains one DNA molecule. DNA is the molecule of inheritance and is made up of a series of genes. The fact that the two DNA molecules in the sister chromatids, and hence their genes, are identical is the key to precise nuclear division.
The process of cell division plays a very important role in the everyday life of human beings as well as all living organisms. If we did not have cell division, all living organisms would cease to reproduce and eventually perish because of it. Within cell division, there are some key roles that are known as nuclear division and cytokinesis. There are two types within nuclear division. Those two types being mitosis and meiosis. Mitosis and meiosis play a very important role in the everyday life as well. Mitosis is the asexual reproduction in which two cells divide in two in order to make duplicate cells. The cells have an equal number of chromosomes which will result in diploid cells. Mitosis is genetically identical and occurs in all living
Microbes are microscopic life forms, usually too small to be seen by the naked eye. Although many microbes are single-celled, there are also numerous multi-cellular organisms. The human body has 10-100 trillion microbes living on it, making it one giant super-organism. Since the first link between microbes and diseases was made, people have been advised to wash their hands. Scientists, however, have recently started to investigate more closely how the microbes that call the human body home affect our health. While some microbes cause disease, others are more beneficial, working with our bodies in many subtle ways.
Meiosis is a special type of cell division that occurs during formation of sperm and egg cells and gives them the correct number of chromosomes. Since a sperm and egg unite during fertilization, each must have only half the number of chromosomes other body cells have. Otherwise, the fertilized cell would have too many.
Compensation involves monetary awards and can be difficult to decide the proper amount of compensation to make the plaintiff whole. In some instance the compensatory damages may seem too far exceed the actual loss of the plaintiff. In addition to over compensation to the plaintiff, another concern is how lawyers are paid for their services. The perception is that lawyers make to much money compared to the plaintiff. Many people, politicians, and companies believe that tort system is defective and requires reform to bring the system more in line with the original intent of tort
Once the sperm fuses with the ovum both chromosomes will pair up and begin the first stages of cell division.
This paper will take a closer look at this phenomenon through an introduction to the field of study regarding the link between birth order and personality. To set the stage, theories of birth order will first be briefly reviewed. The progress of studies from this initial theoretical stage has cause...