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The process of meiosis 1 and 2 essay
Compare the contrast of meiosis and mitosis
The process of meiosis 1 and 2 essay
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The process of meiosis is different from many other forms of cell division. In meiosis the daughter cells only have half the number of chromosomes of the parent. What that means is that the cells produced in meiosis are not exact copies of the original cell. Meiosis is fragmented down into many stages. Every cell in the course of meiosis includes the cell growing, dividing, and spitting, and dividing again in order to create the four cells as the end product. Now I will start with the stages of meiosis. The first stage of meiosis is interphase. Just interphase alone is broken up into 3 different stages, G1 phase, S phase, and G2 phase. In G1 phase the cells grow to get ready for the cell division. In S phase the DNA gets synthesized which …show more content…
Each of the cells have precisely half the number of chromosomes from the original cell. There are many different processes go in this phase so the cell has time to prepare for the second part of meiosis. The only persistent thing is that genetic material does not copy, but in its place it continues to get divided. The next stage is prophase 2 during this phase the chromosomes start traveling to the metaphase plate again, which is at the midpoint of the cell. The next stage is metaphase 2 the chromosomes line up along the center of the cell before it breaks up into two. Then the chromatids point towards the opposite ends of the cell. The next stage is anaphase 2. This is the second to last phase in meiosis and it has many events that happen. The first event is when the sister chromatids separate and move towards the opposite ends of the pole. When this is happening the spindle fibers will lengthen and make the cell bigger. Then the paired chromatids will begin to detach from each other. Now every chromatid pair is considered to be a full chromosome. Now anaphase 2 will start getting ready for the final phase of meiosis. Both cell poles start to move even more apart and now it can be seen as splitting. By the end of this phase each pole
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.
Stem cells are undifferentiated cells that can differentiate themselves into specific cell type. There are two types of stem cells. The first one is the adult's stem cell. These stem cells can be found in various places in an adult human body, like the brain, the bone marrow or the liver. The other type of stem cells is the embryonic stem cells. These cells are found in embryos before its implantation in the mother's uterus. At this stage the embryo is divided in two types of cell. The first one is the outer cluster of cell that forms the embryo that will become part of the placenta once the embryo hatch. And the inner cluster is the source of embryonic stem cell since it consists of undifferentiated cell that will divide and differentiate to form all the organs and tissue needed in an adult organism. As stem cell are undifferentiated cell they can become whatever cell type is needed in an organism and could be the solution to diseases that are, at this date, incurable. (Medical News Today, 2013). Most of the ethic's problem of the stem cells researches come from the embryonic stem cell researches and how the cells are collected. Embryonic stem cells can be obtained in several ways. The first one is after a couple's fertility treatment, there might be some embryos left and the couple can decide to donate their embryos to research. The second option is to collect stem cells from a foetus after an abortion. And the last possibility is to use therapeutic cloning. Using an ovum from witch the nucleus was taken off and the nucleus of a somatic cell, the origin of this cell in the body doesn't matter, it can come from the skin for example, it is possible to create an embryo and get the stem cell from the created embryo. But in all of...
The process of mitosis can take place in either a haploid (23 chromosomes) or a diploid (46 chromosomes) cell. Before a cell can be ready for a mitotic division it must primarily undergo its interphase stage. Following the interphase stage several other stages come into play. These stages are prophase, prometaphase, metaphase, anaphase, and telophase. During each specific stage certain sequences of events take place that assist to the completion of the division.
There are a number of differences in meiosis; starting with the fact that meiosis only occurs in sex cells, producing a sperm and egg. We do have the same stages in meiosis which are prophase I, metaphase I, anaphase I and telophase I, but then again meiosis performs those phases twice to leave behind four cells with half the genetic material in each cell. In the first prophase I, the DNA is replicated and we again are left with chromatid pairs. Just as in mitosis, the mitotic spindles are preparing to pull the centrioles on opposite sides. There is middle to late prophase I which again is different from mitosis because at this time, the chromatids separate differently. Meaning they will not be identical genetically in the end result. Moving into metaphase I, similarly to mitosis the chromatid pairs line up in the center of the cell. The pulling begins again in anaphase I, where there is an arbitrary split-up of the pairs to either side of the cell. In telophase 1, the cell seperates and we are left with two cells containing only 23 chromosomes. Following we then start this process all over
The cell cycle is the process by which cells progress and divide. In normal cells, the cell cycle is controlled by a complex series of signaling pathways by which a cell grows, replicates it’s DNA and divides, these are called proto-oncogenes. A proto-oncogene is a normal gene that could become an oncogene due to mutations. This process has mechanisms to ensure that errors are corrected, if they are not, the cells commit suicide (apoptosis). This process is tightly regulated by the genes within a cell’s nucleus. In cancer, as a result of genetic mutations, this process malfunctions, resulting in uncontrolled cell proliferation. Mutations in proto-oncogene or in a tumour suppressor gene allow a cancerous cell to grow and divide without the normal control imposed by the cell cycle. A change in the DNA sequence of the proto-oncogene gives rise to an oncogene, which
The first sub phase of this is prophase 1 and this is split up into 5 stages. The first one is leptotene and this is where the chromosomes supercoil. The second one is zygotene and this is where the homologous chromosomes form pairs and these are called bivalents. Pachytene is where crossing over occurs between the homologous chromosomes and chiasmata form. Diplotene is where they start to separate but remain attached to each other by the chiasmata. Diakinesis is the last stage and this is where they keep separating and the chiasmata moves to the ends of the chromosome (GENIE, 2010). The second phase is prometaphase and this is where the spindle fibres assemble and the chromosomes become anchored to them by their kinetochores. Metaphase 1 is where the bivalents assort randomly on the metaphase plate. This helps to create genetic diversity. Anaphase 1 is where the bivalents separate and the homologous chromosomes move to opposite poles of the cell. Telophase 1 is where the nuclear envelope reforms after disintegrating in prophase 1. Then cytokinesis is where the cell divides to create two new cells which are haploid (GENIE, 2010). The next main stage is meiosis 2 and this is where each chromosome is split into 2 sister chromatids. Prophase 2 is the first stage and this is where the chromosomes supercoil, the mitotic spindle forms and the nuclear envelope disintegrates. Metaphase 2 is where the chromosomes become attached to the
One chromosome has been donated from each parent cell in order to create a homologous chromosome pair. These chromosomes have identical lengths and gene placement but can contain different alleles. When homologous chromosomes attach at the centromere they create a tetrad, which is defined as a pair of sister chromatids. Once the sister chromatids are attached, the non-sister chromatids participate in crossing over. Crossing over is the transfer of genetic information in order to create greater genetic variability. In metaphase I, the centromere of each tetrad attaches to spindle fibers. These spindle fibers slowly shift the tetrads position to the center of the cell until they are side by side. Immediately after they line up, homologous chromosomes are separated by microtubules called kinetochore fibers that are used to pull sister chromatids to opposite poles of the cell. Once the sister chromatids are on opposite poles of the cell, anaphase I is complete and the cytoplasm of the cell begins to separate. This is known as cytokinesis and occurs during telophase. Once meiosis I is complete, meiosis II begins and repeats each step, however, instead of two haploid cells there will be a total of
The centromere of each chromatid pairs splits and the chromatids separate. The daughter chromosomes are pulled toward opposite ends of the cell along the chromosomal microtubules. Anaphase ends when the daughter chromosomes arrive near the centrioles at opposite ends of the cell.
The differences between the two phases of meiosis are that in meiosis I, while the cell undergoes the phases, prophase I, metaphase I, anaphase I, and telophase I, it causes the cell to divide into two with each of the cells having a double stranded chromosome. But in meiosis II, it is just the division of the the cells from meiosis I. The ending result being that four haploid daughter
Mitosis is broken down into four stages: prophase, metaphase, anaphase and telophase. When living organism needs new cells to repair damage, grow or maintain its condition, cells undergo the cell cycle.
In Meiosis 1, chromosomes in a diploid cell resegregate, producing four haploid daughter cells. It is this step in Meiosis that generates genetic diversity.Meiosis 2 is similar to mitosis. However, there is no "S" phase. The chromatids of each chromosome are no longer identical because of recombination. Meiosis II separates the chromatids producing two daughter cells each with 23 chromosomes (haploid), and each chromosome has only one chromatid.
To start this off, conception is the action of conceiving a child, and pregnancy is the period from conception to birth. They both share the same meaning: the process of getting pregnant. Conception happens when a sperm penetrates on one of the female’s eggs. Then, at around day 14 of a 28 day cycle, the egg leaves the ovary, and it is surrounded by a protective layer of cells. The fallopian tube is lined with cilia, which helps move the egg towards the womb. This is called ovulation. In the next 12-24 hours, the egg waits to be fertilized by a single sperm. The sperm then swims through the womb to meet the egg in the fallopian tube. And the sperm secretes enzymes to help penetrate the outer layer of the egg. Once the
All cells are the product of multiple rounds of cell growth and division, new cells are formed from existing cells, as has been the processes since the beginning of life on Earth. The reproduction of new cells is a very organized sequence of events called the cell cycle. This cycle is the essential mechanism by which all living cells reproduce whether unicellalur or mutlicelluar the basic mechanism is universal. However, variations in the details do occur from organism to organism and the cycle can start at different times in the organism’s life. The Eukaryotic cell cycle usually consist of four phases.
Mitosis is a more advanced binary fission where all the organelles, DNA, RNA and chromosomes are replicated to form two identical cells. Meiosis is cell division for gametes like sperm cells or egg cells that require only half the number of chromosomes than other cells such as skin cells. In meiosis, the chromosomes first condense and sort into pairs which match and ‘relate’ (Homologous pairs). The chromosomes then ‘exchange’ data and information, this varies the outcome of the cell meaning unlike skin cells, and each cell isn’t identical. The cells then part into two groups before the cells start to split like mitosis; however, the process is then repeated in a similar manner, however, the chromatids that separate instead of the whole chromosomes, the result of mitosis is four unique cells rather than two identical
There are certain things that must happen first before the cell can actually split. There is a six step process required during Mitosis. The first five steps of mitosis are called prophase, prometaphase, metaphase, anaphase, and telophase. This is where all the training and preparation is done for cell division. The sixth step is Cytokinesis, and that is when the cell literally splits into two. Like I said, there are certain things in order to happen before it can enter the M phase. first, it must meet the requirements of the certain size and environment. Since in the S phase the cell duplicated it’s amount of chromosomes it be represented as 2N, where N equals the number of chromosomes in the cell. Cells about to enter M phase, which have passed through S phase and replicated their DNA, have 4N chromosomes. Because of this they are now allowed to enter within the M phase to prophase. Here is where the cell thickens up its chromosomes and begin to sprout microtubules from clone centrosomes. Microtubules tub-like are protein filaments and where the chromosomes migrate but are still within the nuclear envelope in the nucleus. There are centromeres, that are inside the chromosomes and during the later process of this phase, specialized microtubules called kinetochores, assemble on the centromere then later attach to these sites. They act like magnets and go