CELL CYCLEBY NURJULAIHA ROSLAN

CELL CYCLE Sequence of stages between cell

division and the next. Time taken to complete one cell cycle

varies with tissues and among spesis. Enviromental factor such as changes in

temperature and pH and declining nutrients levels lead to declining cell division rates.

Cells cycle involve 3 continuous stages--Interphase-Mitosis-Cytokinesis

INTERPHASE Phase between mitotic

division and appears to be resting phase.

Can be divived to 3 phase

G1 phase S phase G2 phase

G1 PHASE RNA and protein produced. Cells grows rapidly. Chromosomes not yet visible. Organelle grows and increase in size. Nucleolus clearly visible.

S PHASE DNA replicates. Synthesis of Histone proteins. Chromosomes have 2 chromatids. Chromosomes not visible.

G2 PHASE Cells increase in mass. More Mitochondria and Chloroplast. Energy store increase. Chromosome start shorten and

condense. Replication of Centrioles

MITOSIS

mitosis Process of dividing a cell by replication and dividing the original chromosomes to obtain 2 new cells identical to one another.

Divided into 4 stages Prophase Metaphase Anaphase Telophase

PROPHASE Chromatin in nucleus begins to

condense. Nucleolus disappear. Mitotic Spindle begin to form. Centrosomes formed and move

apart,push by microtubules. Chromosomes migrate to centre of

nucleus. Disappearance of nuclear envelope.

METAPHASE Nuclear envelope breaks up completely. Centrioles have reaches opposite poles. Attaches to Spindle Fibre in the

Centromere. Chromosomes line up on metaphase

plate.

ANAPHASE Centromere divide and 2 chromatids of

each chromosomes seperates. Spindle Fibre pull the sister chromatids

appart towards opposite pole of cells. Each poles contain a complete set of

chromosomes.

TELOPHASE Spindle fibre disappear and centrioles

divide into two. Chromosomes uncoil and return to

chromatin form. Nuclear envelope reform. Nuclei begin to form.

CYTOKINESIS Splitting the cytoplasm that seperates daughters nuclei into two individual daughter cells.

Furrow forms then it will slowly reduces the diameter of cell until it eventually slices all the way into center of the cell.

Cells seperates completely and 2 complete cell form.

SIGNIFICANCE OF CELL DIVISION

For cell replacement For growth To maintain the genetic stability Reproductive development of organism Continual of life or survival of all

organisms.

WATCH THIS VIDEO!!! For more understanding ,watch this

video through this link.. YouTube - Mitosis.flv or http://www.youtube.com/watch?v=ATlU

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