Post on 30-Jan-2016
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IZAT EZATTE BINTI MUSA4 UTM
THE NECESSITY FOR THE REPRODUCTION OF NEW CELLS ORGANISMS.Mitosis is the process of cell division that produces
two daughter cells which are genetically to each other and to their parent cell.
The significance of mitosis in living things: Repair and replace the damaged or dead cells Increases the number of unicellular organisms. Ensures that new cell are genetically identical to the
parent Preserve the diploid number of chromosomes
Increases the number of cells in individuals(single-celled
organisms) Aids in growth process(multi-celled organisms)
The phases in the cell cycleCell cycle-the life of a cell from the time it is
produced until it completely divides into two new daughter cells.
Activity of the cell during mitotic division:Preparing for the divisionProduce cytoplasm and organelles-formation of
daughter cells.Two major phases:
InterphaseMitotic cell division(M Phase)
Phase in Cell cycle
InterphasePHASE DESCRIPTIONS
G1(FIRST GAP) •The size of cells increases •RNA is produced•Synthesise protein and new organelles•Chromosome cannot be observed clearly and known as chromatin
S(SYNTHESIS) •DNA synthesis•The DNA replication takes place•The copied chromosomes contain two sister chromatids which are identical
G2(SECOND GAP) •Cell preparing for division(mitosis)•The cell grows,produces organelles,protein and membrane•Nucleus is well-defined•Chromosome duplication completed•DNA loosely packed in long chromatin fibres
1. Interphase This is the resting or
non-mitotic of the cell cycle
It comprise G1,S and G2 stage of the cell cycle
DNA is replicated during the S phase of interphase
The M phase(mitosis and cytokinesis) PROPHASE
If the first stage of mitosis The chromosomes
condense and become visible
The centrioles form and move toward opposite ends of the cell(the pole)
The nuclear membrane dissoves and the mitotic spindle thread is formed(from the centrioles)
Spindle fibers from each centriole attach to each sister chromatid at the kinetochore
Chromatids are connected at the centromere
METAPHASEThe chromosomes
lined up on the cell equator which is the metaphase plate
The spindle fibres are formed completely
ANAPHASESpindle attached to
kinetochores begin to shorten
This exerts a force on the sister chromatids and pulls them apart
Spindle fibres continue to shorten,pulling chromatids to opposite poles of the cell
Early anaphase
Late anaphase
TELOPHASE
Both chromosomes have reached the opposite poles
The chromosomes decondensed
The nuclear enveloped is formed
Nucleus reformedThe spindle fibres
dissappearOnce separate,the
chromatds are again called chromosomes
Two daughter nuclei are formed with identical set of chromosomes
CytokinesisCytokinesis is the process of the cytoplasm division
after the separation of chromosomes
CYTOKINESIS IN PLANT CELL
•The vesicles move to the equator between the two nuclei and fuse to form two membranes that become cell plate
•The cell plate grows upwards•The new cell wall is laid down between membranes and fuses with the existing cell wall
CYTOKINESIS IN ANIMAL CELLS
The vesicles move to the equator between the two nuclei and fuse to form two membranes that become cell plateThe cell plate grows upwardsThe news cell wall is laid down between membranes and fuses with the existing cell wall
The importance controling mitosisTo ensure that organism can function
properlyTo ensure that organisms can grow and
develop normallyTo help in repairing damage cells and
tissues for the survival of life
The effects of uncontrolled mitosis in living things
It due to the changes of gene which control the cell cycle e,g:The growth of cancerous cell
Cancerous cells could lead to the death of the organism if it is not prevented from invanding and destroying neighbouring cells
This condition can be caused by certain virus,toxic chemical susbtances
The cells divide very fast and unregulated.(Tumour) Benign tumour-Abnormal cells that remain at the original site
and be removed by surgery Malignant tumour-becomes invasive and spreads to
neighbouring tissues and cells (cancer)
The application of knowledge on mitosis in cloning Production of genetically identical individuals
Cloning of sheep
Producing genetically identical organisms which carry a useful gene
A piece of DNA carrying a gene of interest and a gene for antibiotic resistance
The cells is grown on a medium containing the antibiotic so that only the cells with the inserted DNA will survive
The nuclei from surviving cells is inserted into unnucleated egg cells
The egg cells is implanted into the surrogate mother Clone which carry the useful gene are born
Application of cloning technology is important to:
Produce genetically identical organs for transplantation
Produce human tissuesRepopulate endangered species
The advantages and disadvantages of cloning
Advantages Ensure the continuity of hereditary traits from the parent to the clonesIncrease the rate of production and the quality of the productsGood qualities of the plants and animals can be selected and maintained in the clonesMany clones are produced in a short timeCan be carried out any time of the year
DisadvantagesRaise ethical issues on human The resistance of the clones towards diseases and pests is the same.If a clone is infected with a disease or attacked and die
Raise ethical issues on human cloning