Cell Division
Cell plate Carcinogen Oncogenes Haploid cell Diploid cell Chromosome Gene Interphase Anaphase Metaphase Telophase Keywords Mitosis Meiosis Centromere Cleavage furrow Middle lamella
What is cell continuity? It is when cells develop from other existing cells. It can occur by mitosis or meiosis.
What is a chromosome? A chromosome is a section of DNA and protein. Chromosomes are found in the nucleus of a cell. What is chromatin? It is a mass of chromosomes which occurs when the cell is not dividing.
Chromatin
Human Chromosomes
Haploid cells A haploid cell has one set of chromosomes. Sperm and eggs are haploid cells (n = 23) n = 3 Chromosome
Diploid cells A diploid cell has two sets of chromosomes. Chromosomes occur in pairs in a diploid cells. Diploid cell in humans: 2n = 46 2n = 6
The cell cycle The cell cycle includes the period interphase and mitosis.
90% of the cell cycle Interphase Cell is not dividing in this phase. Chromosomes are elongated to form a mass of chromosomes (chromatin) During the interphase the cell is getting ready for mitosis so it is producing identical copies of everything
Interphase Chromosome duplication occurs late in the interphase.
What is mitosis? Mitosis is a form of nucleus division in which one nucleus divides into two nuclei. Both nuclei are identical.
Steps involved in mitosis I Party Monday And Tuesday Mitosis Prophase Metaphase Anaphase Telophase
Prophase Chromatin start to contract and become visible double stranded structures. The nucleolus disappears. Spindle fibres appear in the cytoplasm. Nuclear membrane begins to break down.
Spindle fibre Prophase Nuclear membrane breaks down Double stranded chromosome X X X X
Metaphase Nuclear membrane completely breaks down Spindle fibre attaches to each centromere at each end of cell. The chromosomes line up across the middle or along the equator of the cell.
Metaphase
Anaphase Spindle fibres contract. Pulls one strand of each double stranded chromosome to each end of cell. Chromosomes pulled to the end of cell Fibre contracts
Telophase Spindle fibre breaks down. The chromosomes at each pole begin to length and form chromatin. A nuclear membrane forms around each mass of chromatin at each end of cell. The two nuclei are now identical.
Telophase Nuclear membrane forms Chromosomes elongate to form chromatin
Mitosis - YouTube Videos on mitosis
Cell division in animal cells Cell division occurs in animals by a process called a cleavage furrow. Cleavage furrow becomes deeper and divides the cytoplasm and the cell spilts.
Cell division in plant cells Vesicles gather between the two nuclei. Vesicles form a structure called the cell plate. A middle lamella forms in the middle of the cell plate.
Cancer When a cell loses the ability to control the rate of mitosis and the number of times it occurs. This forms a mass of cells called a tumour which can be benign or malignant. 3D Medical Animation - What is Cancer? YouTube http://www.youtube.com/watch?v=8lhqllh46yi
Benign tumour In benign tumours the cells stop dividing after some time. Not life threatening. They do not invade other tissues.
Malignant tumours Uncontrolled division of tumours. They invade other cells (metastasis). CLD Inc - Benign Versus Malignant - YouTube
Causes of cancers: Normal genes are altered to form cancer causing genes called oncogenes. Cancer causing agents are called carcinogens. Examples of carcinogens: cigarette smoke, asbestos, ultraviolet radiation.
Meiosis It is a form of nuclear division in which the daughter nuclei contain half the chromosome number of the parent nucleus. Male cell 46 Female cell 46 Sperm 23 Egg 23 Fertilisation 46
Function of meiosis Allows for sexual reproduction to occur. Allows for greater variation within a species.
Differences between mitosis and meiosis Mitosis Meiosis Same number of chromosomes in parent and daughter cell. Half the number of chromosomes in daughter cells compared to parent cell One cell divides into two new cells. One cell divides into four new cells. Genes in new cells are identical to parent cell Genes in new cells are different to parent cell
Video Meiosis YouTube When the egg meets sperm - YouTube
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