Published on March 4, 2014
* Chromosomes form when the chromatin network in the nucleus of the cell, coil up, shortens and thickens. * Each organism has a specific amount of chromosomes. * All humans have 46 chromosomes. * These chromosomes are arranged in identical pairs called homologous chromosome pairs – * Therefore humans have 23 homologous pairs of chromosomes. * These chromosomes is only visible during cell division processes. * One chromosome consist of 2 chromatids and one centromere that attach the chromatids together. * Each chromatid consist of genes which in turn consist of DNA.
* X and Y chromosomes: gonosomes/sexchromosomes Colored bands represents different genes
The cell cycle includes the following phases: * Interphase * Mitosis * Cytokinesis * Growth The result is 2 identical cells.
* *Allow an organism to grow. *Repairs damaged cells/tissue. *Replace dead cells/tissue. *Reproduction in some simple organisms.
* * In all somatic cells (include all body cells and excludes the sex cells – sperm/egg cells)
* * CONSIST OF A FEW PHASES: * INTERPHASE * PROPHASE * METAPHASE * ANAPHASE * TELOPHASE
* * Cell builds up enough energy for division process. * DNA replication occurs * Cell look normal, like before division
* * Nuclear envelope and nucleolus disappear. * Chromatin become more tightly coiled, and condenses into individual chromosomes. Chromosomes arrange randomly in the cell. * Centrioli move to opposite poles, with spindle fibers stretching between them.
* * The centrioli reached the opposite poles with the spindle fibers in between. * The chromosomes arrange randomly on the equator, each single chromosome attaching to a separate spindle fiber by means of the centromere.
* * The spindle fibers pull tight. * The centromers attaching the chromatids of the chromosomes split in half. * Daughter chromosomes move to opposite poles.
* * Daughter chromosomes reach poles. * Nuclear envelope surrounds chromosomes. * Nucleolus reappear at each pole. * Chromosomes become less condense forming chromatin. * Two identical nuclei has been formed
* * Invagination of the cytoplasm and plasma membrane occurs. (Cleavage furrow forms in animal cells and a cytoplasmic plate forms in plant cells) * Continues until the cell in divided into 2 separate cells. (Identical to one another and to the original cell)
* Summary of the different phases in mitosis *
* * Cancer is caused by the loss of cell cycle controls in cancer cells. * Cancer cells usually continue to divide well beyond a single layer, forming a clump of overlapping cells called a tumor. * Malignant tumors invade surrounding tissues and can metastasize exporting cancer cells to other parts of the body, where they may form secondary tumors. * They do not exhibit anchorage dependence or density dependent inhibition.
* Ovarian cancer cells dividing
Cell division may or may not occur at this time depending on the organism. ... There are many cells where mitosis and cytokinesis occur separately, ...
In order to better understand the concept of cell division and genetics, some basic definitions are in order: gene - basic unit of heredity; codes for a ...
Mitosis is nuclear division plus cytokinesis, and produces two identical daughter cells during prophase, prometaphase, metaphase, anaphase, and telophase.
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The five phases of mitosis and cell division tightly coordinate the movements of hundreds of proteins. How did early biologists unravel this complex dance ...
This animation demonstrates the stages of mitosis in an animal cell. ... Download the Cell Division PowerPoint; Get a Free Mitosis Worksheet;
For organisms to grow, develop and maintain life, cells must divide. Cell division involves stages of interphase, nuclear division & cytokinesis.
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Meiosis uses many of the same mechanisms as mitosis, the type of cell division used by eukaryotes to ... of the chromosomes at the first meiosis division.
Mitosis is a process of nuclear division in eukaryotic cells that occurs when a parent cell divides to produce two identical daughter cells. During cell ...