Transcript Mitosis Powerpoint

Phases of Cell Division
 Interphase
(stage between cell division)
Prophase
 Metaphase
 Anaphase
 Telophase

By: Ms. Reis
Review
 Each
body cell
has 2 sets of 23
chromosomes
 Therefore
a
normal human
cell has 46
chromosomes
Cell Division
Cells divide for several reasons:
 To repair and heal tissues
 To exchange materials efficiently with their
environment. Food comes in and wastes
go out.
 To send messages to the nucleus
efficiently.
Mitosis
 Mitosis
is a process of cell division
producing two daughter cells from a single
parent cell.
 The
daughter cells are identical to one
another and to the original parent cell.
 Note:
Parent cell - the cell that divides
Daughter cell – the cells that result
from cell division
Down Syndrome

Karyotype
A
photograph showing the number,
shapes and sizes of chromosomes in a
cell.
 All pairs of chromosomes are homologus
(identical in size and shape) except the
sex chromosomes (23rd pair)
 One chromosome comes from the father
(paternal) one chromosome comes from
the mother (maternal
The Cell Cycle
Interphase
 The
cell prepares
for mitosis by
growing rapidly
 Chromosomes
duplicate in the
nucleus
 Longest stage of
the cell cycle
Chromatin


DNA molecules & proteins in a tangled fibrous mass
during interphase. Chromatin is composed of 60%
protein, 35 % DNA, and 5 % RNA.
Centromeres

The original
chromosome and its
duplicate are attached
at the centromere.
 Sister chromatids –
the original
chromosome and its
duplicate while
attached at the
centromere.
Prophase
 Chromosomes
shorten and thicken
 Nuclear membrane
dissolves
 Centrioles move to
opposite poles of cell
in animal cells
 Formation of spindle
fibers
Metaphase
 46
sister
chromatids line
up at the
equatorial plate.
Anaphase
 Spindle
fibers pull
sister chromatids
(duplicated
chromosomes)
apart to the
opposite end of
the cell.
 Centromeres
divide.
Telophase
 Cell
begins to
pinch in two
 New nuclear
membrane starts to
form
 Cytokinesis division of the
cytoplasm and
organelles
between both
daughter cells
Conclusion
 Each
new cell ends up with the same
amount of genetic material as the
original cell.
 Both
daughter cells are identical to
the parent cells.
Cytokinesis
 In
animal cells the cell membrane pinches
inward at the equator of the cell, producing
a furrow.
 In
plant cells a cell plate is formed across
the equator of the cell. Cellulose is added
to the cell plate to form a new cell wall.
Discussion Question
 How
many chromosomes would you
expect to find in each daughter cell
after mitosis?
 Predict what might happen to each
daughter cell if all the chromosomes
moved to only one side of the cell
during anaphase.
 Why is it necessary to duplicate the
nuclear material?