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