Download The Cell Cycle and Mitosis:

1.2 The Cell Cycle
& Mitosis
“You Complete Me”
A process where one parent cell
gives rise to two daughter cellsexact replicas of the original cell.
The Cell Cycle
Importance of cell division:
1. Helps organisms grow.
2. Helps organisms repair.
3. Helps organisms reproduce.
Stages of Cell Cycle
There are 3 stages to the cell cycle:
1.Interphase: growth and preparation
2.Mitosis: the process of duplicating the
nucleus, (PMAT)
3.Cytokinesis:
division of cytoplasm and organelles
Stage 1: Interphase
Onion root tip (on left side),
whitefish (on right side)
• The longest of all 3 stages of the cell cycle
• The cell grows and prepares to divide by
duplicating its DNA and organelles so that it can
be shared between the 2 new cells.
• The DNA strands, chromosomes copy
themselves, they are now identical strands of DNA
• This now allows for the new cell to have the same
genetic information as the parent cell.
Chromosomes duplicate
Each strand is called a chromatid
centromere
Stage 2: Mitosis
• Mitosis is the stage where
the nucleus divides.
• TWO copies of the DNA
separate to opposite ends
of the cell to make TWO
new daughter cells.
• There are 4 main
phases:
1) Prophase, P
2) Metaphase, M
3) Anaphase, A
4) Telophase, T
Phase 1 of Mitosis: Prophase
Major processes during
this phase:
• Chromosomes thicken and become
more visible bodies, each pair is
made up of identical strands.
• Nucleolus disappears
• Nuclear membrane around the
nucleus begins to dissolve.
• 2 centrioles move to opposite ends
of the cell
• Mesh-like spindle fibres form
between centioles
• Chromosomes begin to attach to
spindle fibres.
Phase 2 of Mitosis: Metaphase
• Chromosomes
attached to spindle
fibers line up in the
middle (the equator)
of the cell
• Spindle fibers attach
to the centromeres of
the chromosomes.
Phase 3 of Mitosis: Anaphase
• The sister chromatids
separate and are pulled to
opposite poles of the cell.
• Each separate chromatid is
called a daughter
chromosome.
• One complete set of
chromosomes moves to
each end of the cell.
Phase 4 of Mitosis: Telophase
• Spindle fibres begin to
disappear
• Daughter chromosomes
stretch out, and become
thin and invisible again.
• A new nuclear membrane
begins to form around the
nucleus at each end of the
cell.
• There are now 2 separate
nuclei and the cell is ready
to split into 2
Stage 3 of Cell Cycle:
Cytokinesis
• In this last stage of the cell cycle, the
cytoplasm and other organelles are
distributed to the two ends of the cell.
• In an animal cell the cell membrane
pinches in called the cleavage furrow.
• This separates the dividing cell into 2
new daughter cells.
• Each daughter cell has a nucleus with a
complete copy of the parents cell’s DNA
and its own organelles.
cleavage furrow
This cycle this repeats
itself again!
Body Cell Chromosome Numbers
During Mitosis
46
46
Parent Cell
46
2 Identical
Daughter
Cells
Answers:
A. Telophase
B. Prophase
C. Cytokinesis
D. Metaphase
C
D
B
A
Can you identify these stages?
Mitosis - Video
• http://www.bing.com/videos/search?q=mit
osis&FORM=HDRSC3#view=detail&mid=
4EB754393EBFF004C8EC4EB754393EB
FF004C8EC
Homework
1. Read Pages
2. Complete:
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