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Cell DivisionPrepared by:
Joel P. Ogoc, Ed. D.
Master Teacher II
Science Department
ZNNHS
Refers to the process that results in the increase in the number of cells
This happens so the body produce new cells that replace damaged ones
Cell division that takes place on body cells results to increase in size
Two processes occur during cell division namely:
Division of the nucleus (Mitosis)
Division of the cytoplasm (Cytokinesis)
Cell Cycle
Refers to the life cycle of the cell
It is divided into two (2) stagesInterphase
Mitotic phase
Interphase refers to the period after 1 cell division and before another cell division
It is divided into 3 substages
G1 or First GapThe period during which the new cells initially growsThis occurs from the formation of new cells until the DNA starts to replicateOccurs about 4 hours
S or Synthesis
The middle stage where the chromosomes duplicate in preparation for the next cell divisionThis occurs about 10 hours
G2 or Second Gap
This falls between S and the next cell divisionIt represents the time of growth in preparation for cell divisionIt occurs about 4 hours
During interphase, the nucleus is surrounded by its nuclear membrane
One or more nucleoli are visible inside the nucleus
The chromatin are very thin and tangled; appears as an irregular mass
The DNA is stretched out thin in the nucleus to make duplication possible
All proteins that the cell needs for its activities during its whole life is made during this time
Thus the chromatin and DNA are doubled during interphase
Mitosis is a way of dividing the nucleus with its replicated DNA
Resulting daughter cells have Same number of chromosomes
Similar characteristics
It occurs for about 2 hours
Cytokinesis refers to the division of the cytoplasm
Comparing Plant and Animal Cell Mitosis
Plant cell
Do not have centriole
Do not form asters
Spindle fiber still form
Daughter cells are formed by cell plate
Cell walls form from inside going out
Animal cell
Centrioles also travel and replicate
It forms asters for the spindle fiber
Daughter cells are formed by a cleavage in the cell membrane
Furrows are formed from outside goping in
That’s all for today
Study for the check up quiz
tomorrow