mitosis roslyn in biotechnology

1. Mitosis
 Purpose: occurs in
somatic (body) cells
for growth and repair
of tissue (ex. Growing,
or healing an injury).
Occurs in both plants
and animals: asexual
reproduction, (starting
a new plant from a
stem/leaf of another
one)

2.  Method: mitosis involves
one duplication of nuclear
material, and one division of
the cell. Chromosome
number is maintained
(diploid  diploid (normal
chromosome #).
 Daughter cells are identical
to each other and to the
parent cell.

3. The cellular life cycle

4. Cell Cycle:
 Interphase – mostly the active growth and
metabolism of the cell, but at the end of
interphase, DNA (found in chromosomes)
duplicates (makes a copy of itself)
 During interphase, chromosomes are referred to as
chromatin – a loosely scattered arrangement of
chromosomes

5. Mitotic Phase
 Period of cell division
 Shortest stage in the cell
cycle

7. Chromosomes Vs. Chromatin
 DNA exists in Chromatin
form in the nucleus.
 The chromatin condenses
to form Chromosomes
during cell division

9.  INTERPHASE: The normal
growth and development stage
of cells
 During this stage cellular
activities proceed normally
 There is no DNA replication
 Cell produces proteins through
protein synthesis
 Cells usually increase in size
and mass
 Chromosomes are not readily
visible and are intertwined in
the nucleus

10.  This is known as the “G1 stage” of the cellular cycle. The cell
spends the majority of its life in this stage.
 The cell then enters the “S” or Synthesis stage. During this
stage of Interphase DNA replication occurs and the
chromosomes make identical copies of themselves.
 The “G2 stage” is a short period of growth and other
preparations necessary for mitosis.

11. Interphase in an animal cell

15.  PROPHASE: At the end of
Interphase the
chromosomes replicate
themselves. This signals
the start of prophase
 During prophase the
centrioles migrate to
opposite poles of the cell
 The nuclear membrane
breaks down and
dissolves
 The chromosomes
shorten & thicken

17. Prophase in a plant cell

18. Prophase in an animal cell

19.  At this point the two replicas of the parent chromosomes are called
chromatids
 The two chromatids are joined together in a region known as the
centromere
 As prophase continues some of the cells cytoskeleton (made up of
microfilaments) form the spindle fibers
 By the end of prophase an entire network of microfilaments has
formed and is attached to the chromatids at the centromere
 The cell now enters METAPHASE

20. Metaphase begins as
the chromatids begin
to move towards the
equator of the cell
When all the
chromatids have
reached the center of
the cell AND begin
to separate
ANAPHASE begins

23. Metaphase in an animal cell

24. Metaphase in a plant cell

25. What differences can you describe
between the 1st Meiotic metaphase
and the metaphase in mitosis?
What differences can you describe
between the 2nd Meiotic
metaphase and the metaphase in
mitosis?

26.  Anaphase begins with the
separation of chromatid pairs
 Once separated each
chromatid is called a
chromosomes
 By late anaphase an equal
number of chromosomes has
reached each pole
 The cell membrane begins to
change shape getting thinner
in the middle

28. Anaphase in an animal cell

29. Anaphase in a plant cell

30.  Telophase: during early
telophase the
chromosomes uncoil
 The fragments of the
nuclear membrane
begin to reassemble
around the
chromosomes
 The nucleolus reappears
 The cell membrane, and
cell plate in plant cells,
begins to form in the
space between the two
new nuclei.

33. Telophase in an animal cell

34. Telophase in a plant cell

38.  The two daughter cells separate by
a process called cytokinesis
 The cell membrane returns to
normal and the new daughter cells
enter Interphase
 And the cycle continues…..

41. Vocab Words