Transcript Chapter 3.2 Cell Division

Chapter 3.2
Cell Division
Life Science
What causes organisms
to grow??

Many organisms start as one
cell…what happens to these cells?
– Cells divide!! One becomes two, two
becomes four…

Multi-cellular organisms grow because
of CELL DIVISION!
Cell Division

Cell Division- increases the total
number of cells and causes multicellular organisms to grow and
develop.
3 Functions:
1. Growth
2. Development
3. Repair
The Cell Cycle

Cells contain periods of formation,
growth and development, and death
called a life cycle.
– Forms, Grows/Develops, Dies.

The length of the cycle depends on the
type of cell.
CELL CYCLE:
Page 81
cell grows and carries out normal
activities; organelles duplicate
DNA replicates and
chromosomesduplicate
cell grows and
prepares for mitosis
Mitosis

Mitosis (mi TOH sus) – process in
which the nucleus divides to form two
identical copies of cell.

Do YOU remember the steps or
phases of Mitosis?
BEFORE MITOSIS
Interphase

Interphase - phase where Eukaryotic
cells spend most of their “life”
– A period of growth and development.
– Cell duplicates its chromatin and
prepares for cell division.

Cell is not dividing***

Chromatin, Chromatid, Chromosome …
MITOSIS BEGINS
Prophase

Prophase
“P” for Pairs
– Nucleus disappears
– Centrioles - two small structures that
move to opposite ends
– Spindle fibers - (threadlike) begin to
stretch across the cell.
Metaphase

Metaphase-
“M” for Middle
– Chromosomes line up across the center
of the cell
– Spindle Fibers attach to the centromere.
Anaphase

Anaphase-
“a” for aPart
– Centromere divides
– Chromatid Pairs separate and moves to
opposite ends of the cell
– Spindle Fibers pull similar to a fishing rod
Telophase
 Telophase-
“t” for two
– Spindle Fibers disappear
– New Nucleus is formed (nuclear
membrane)
– Two Cells form.
AFTER MITOSIS
Cytokinesis- the division of the parent
cell’s cytoplasm.
(Page 85)

 In
animal cells, the cell is pinched
into two identical daughter cells.
http://www.cellsalive.com/mitosis.htm
Results of Mitosis
 Each
cell in your body (except sex
cells) has the same number of 46
chromosomes (23 pairs)
 Allows
growth and replaces
damaged cells