Cell Cycle
IPMATC
How do people grow??
How does a human start as one cell
and end up a baby in 9 months?
By increasing the number of cells in their
body.
Need three steps to make this happen!
Interphase
Mitosis
Cytokinesis
3 stages of the Cell Cycle
(the cell’s life)
Interphase
Mitosis
Cytokinesis
Between each stage, the cell “checks” to
see if it is OK to proceed to the next stage.
Cell Cycle Stage 1:
Interphase
 Longest stage of the cell
cycle
 Includes G1, S, and G2
phases
 Distinct chromosomes are
NOT visible
 Period of major cell growth
 Ends with the duplicating of
the chromosomes
 Humans: 46  92
G1
Growth phase
Develops a mature functioning cell
Cells prepare for DNA replication
S Phase
Synthesis phase
Cell makes a copy of its DNA.
Humans: 46  92
G2
2nd Growth Phase
Cell prepares to divide nucleus
http://www.youtube.com/watch?v=zGVBAHAsj
JM
Cell Cycle Stage 2: Mitosis
Cell’s nucleus and nuclear material divides
 4 stages  P M A T
P – Prophase
M – Metaphase
A – Anaphase
T - Telophase
Cell Cycle Stage 3: Cytokinesis
Cyto – cell. Kinesis – movement.
Cytoplasm divides to form 2 new cells.
Cytoplasm: filler material in cell.
Your turn:
 On your own piece of paper: Draw your own representation of the cell
cycle C phase.
 Then, write a brief explanation of what is going on in each phase.
 Don’t worry about 4-8, we will cover that at a later time.
2. ___
3. ___
1. ___
9. ___
8. ___
7. ___ 6. ___
4. ___
5. ___
Cell Division: Mitosis
PMAT
 1 cell
(parent cell)
2 cells
(daughter cells – identical to
each other & parent)
8
16
8
8
6
12
6
6
46
92
46
46
Mitosis
 Mitosis happens because cells can only grow so large . . .
then they need to divide.
 Exception: Muscle & nerve cells don’t divide once mature.
Important in the growth and repair of multicellular
organisms.
Each cell is genetically identical to the other and to the
parent cell from which it was formed.
Before Prophase
 Duplicated chromosomes are hooked together by a
centromere and now called sister chromatids
 Chromosomes condense and become fatter and shorter
 Nuclear membrane disappears
 Centrioles move to opposite ends of the cell
 Spindle fibers begin to form at the poles
(thin)
(Short/fat)
Chromatin = Chromatid=Chromasome
Prophase
Metaphase (meta – middle)
Chromosomes line up in the MIDDLE of
the cell at the equator
Spindle fibers that started forming in
prophase become attacked to the
centromere of the chromosomes
Metaphase
Anaphase
Centromere split
Sister chromatids are pulled APART and
dragged to opposite poles
Full set of chromosomes is now present at
each pole
Anaphase - Apart
Telophase
 Chromosomes reach their respective poles.
 Chromatin uncoil & become thin and long again.
 Spindle fibers break down & disappear.
 Nuclear membrane reappears.
 Cleavage furrow forms.
Stage 3 of the Cell Cycle: Cytokinesis
Cell’s cytoplasm divides.
2 new cells are created.
2 smaller Daughter Cells are formed.
Mitosis
Happens in body cells. (Somatic Cells)
1 cell  2 identical cells
https://www.youtube.com/watch?v=pOsAbTi9tHw
MEIOSIS
MITOSIS
Happens in ___________ cells.
____ cell  ____ cells.
Goes through ____ division
and includes I–P M A T–C.
 Happens in ___________ organs.
 ____ cell  ____ cells.
 Goes through ____ divisions.
 Division 1: I – P M A T–C
 Division 2: P M A T-C
 Skips which phase? ______________
REASONS cells go through this?