Life depends on cell division or the reproduction of cells. Mitosis and meiosis are both used to help the cell divide. Mitosis and Meiosis both consists of 5 different stages that help it divide. These 5 stages are: prophase, prometaphase, metaphase, anaphase and telophase. Mitosis results in two diploid cells. In prophase, it is the first and longest stage, the nucleoli begins to disappear and the chromosomes begin to condense as well. Also in this stage the mitotic spindle begins to form in the cell. The second stage prometaphase, the kinetochore begins to appear on the two sister chromatids of the chromosomes and the proteins attach to them causing movement like a tug of war motion . The nuclear envelope begins to fragment in the cell as …show more content…
At the end of this stage the cell has a full and set collection of chromosomes. In the last phase of mitosis, telophase, the daughter nuclei form. Nuclear envelopes also begin to develop again and any microtubules left over are no longer present in the cell. At the end of mitosis there are two genetically identical cells are complete. Meiosis unlike mitosis has two cell divisions, Meiosis I and Meiosis II. In prophase I of meiosis I, the chromosomes begin by pairing with its homolog and this is also where crossing over occurs. In this stage just like prophase in mitosis the nuclear envelope breaks down and the mitotic spindle begins to develop as well. In Metaphase I the homologue chromosomes line up at the metaphase plate and the kinetochore microtubules attach to both ends of the chromosome. In anaphase I the homologs move to opposite ends of the poles and the homologs also begin to separate as well. In telophase I the sister chromatids appear and each have a full set of duplicated chromosomes. Then following telophase I, prophase II occurs which is when the spindle apparatus begins to appear and the two chromatids begin to the metaphase II
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.
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.
Sexual reproduction is that the union of male and feminine gametes to create a fertilised egg or zygote. The ensuing offspring inherit one-half their traits from every parent. Consequently, they 're not genetically similar to either parent or siblings, except within the case of identical twins. As theorised by Mendel, adults are diploid, meaning as 2N, having 2 alleles offered to code for one attribute. The gametes should be haploid, signified by N, containing just one allele in order that once 2 haploid gametes mix, they manufacture a traditional diploid individual. The method where haploid sex cells are created from diploid parents is known as meiosis, and it happens solely within the reproductive organs.
Cell division is extremely important; cells must divide in order to maintain an efficient volume to surface area ratio, allow organisms to grow and develop, and repair any damaged tissue. Cells are able to do all this through two processes: meiosis and mitosis. Without these processes, humans would not be able to do many of the basic functions we are so accustomed to, including growing, healing even the smallest cuts, and even reproducing! However, meiosis and mitosis, although both procedures for cell division, are very different.
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...
The nucleus is one of the most important organelles in a eukaryotic cell. The shape of the nucleus is generally spherical, it should be oval, disc formed reckoning on the sort of cell. The nucleus was found by Robert Brown in 1831 while he was looking at orchids under a microscope. He discovered a blurred area in the cells of the flowers and called it the areola or the nucleus.
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.
The differences between the phases of mitosis and meiosis are that in mitosis, it has 1 cell division, duplicates the DNA, occurs in somatic cells, and no crossing over happens. In meiosis, it has 2 cell divisions, reduces the DNA, occurs in gametes or sperm and egg cells, while crossing over happens. They are both similar in which they both create daughter cells, headed by at least one round of DNA replication, and have similar stages for cell division.
Cells, cells make up every living organism which makes up this world, and those cells each have a function. The functions and purposes of each cell are intended to help the organism which the cells make up to survive in their environment. Cells have a life cycle which causes them to live and die, replicate and repeat the cycle. There are different parts to the cell's life cycle. Stages in which the cell grows, replicates, and go into their functional stage which is where they carry out with their normal processes. There are cell checkpoints in part of the cell cycle in which the cell decides whether or not to move forward into cell division. The cell division is a very important part of the cell cycle since that is how humans grow, recover and survive in the world.
There are two main types of cells in the world. The simplest cells such as bacteria are known as Prokaryotic cells, and human cells are known as Eukaryotic cells. The main difference between each of these cells is that a eukaryotic cell has a nucleus and a membrane bound section in which the cell holds the main DNA which are building blocks of life.
The biological approach emphasizes physical and biological bases of behaviour. It looks at how brain functions influence different behaviours and personality. The study of nervous system has played a major role in the development of biological approach to psychology. On the other hand, the psychoanalytic approach explains personality, motivation and psychological disorders by focusing on the influence of early childhood experiences, unconscious motives and conflicts. This essay attempts to explain biological and psychoanalytic approaches to psychology with focus on their core assumptions, key features, similarities and differences.
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.
Once the sperm fuses with the ovum both chromosomes will pair up and begin the first stages of cell division.