The document outlines the key stages of the cell cycle, including interphase (G1, S, G2 phases), mitosis, and cytokinesis. It describes that interphase involves DNA replication and protein synthesis. The four stages of mitosis are then described: prophase, metaphase, anaphase, and telophase. It is explained that mitosis produces two genetically identical daughter cells through the duplication and separation of chromosomes. Cell division through mitosis is described as essential for growth, development, tissue repair, and asexual reproduction.

1. IB Biology
2 Cells
2.5 Cell Division
All syllabus statements ©IBO 2007
All images CC or public domain or link to original material.
Jason de Nys
http://commons.wikimedia.org/wiki/File:Scotchquaileggs.jpg

2. 2.5.1 Outline the stages of the cell cycle, including interphase (G1, S, G2), mitosis and cytokinesis
Interphase is the longest
portion of a cell’s life and
has three subdivisions:
First Gap
G1
http://commons.wikimedia.org/wiki/File:First_gap_cell_lifecycle.svg

3. Synthesis
S
http://commons.wikimedia.org/wiki/File:Synthesis_cell_lifecycle.svg

4. Second Gap
G2
http://commons.wikimedia.org/wiki/File:Second_gap_cell_lifecycle.svg

5. Mitosis:
4 Main stages
http://commons.wikimedia.org/wiki/File:Prophase_procariotic_mitosis.svg
ttp://commons.wikimedia.org/wiki/File:Metaphase_procariotic_mitosis.svg
media.org/wiki/File:Anaphase_procariotic_mitosis.svghttp://commons.wiki
The cell divides it’s chromosomes into 2 identical sets
media.org/wiki/File:Telophase_procariotic_mitosis.svg
Detail in 2.5.4

6. Cytokinesis
http://commons.wikimedia.org/wiki/File:Cytokinesis_eukaryotic_mitosis.svg

7. Stage Events
Gap 1 (G1) • Protein Synthesis
• Organelles produced
• Cytoplasm increases in size
Synthesis (S) DNA is duplicated
Gap 2 (G2) • Organelles produced
• Cytoplasm increases in size
Mitosis The cell divides it’s chromosomes into two
identical sets
4 Stages
• Prophase
• Metaphase
• Anaphase
• Telophase
Cytokinesis The parent cell divides into two daughter cells

8. 2.5.2 State that tumours (cancers) are the result of uncontrolled cell division and that these can
occur in any organ or tissue.
In cancerous cells, control of mitosis has been lost
and they divide… and divide… and divide.
This leads to tumours (cancer tissue) that displaces
healthy tissue and interferes with proper function.
Cancer can arise from any cells capable of mitosis
Background: A Brenner tumour in
an ovary. These are usually
benign, but can be malignant
http://commons.wikimedia.org/wiki/File:Brenner_tumour_intermed_mag.jpg

9. 2.5.3 State that interphase is an active period in the life of the cell when many metabolic
reactions occur, including protein synthesis, DNA replication, and an increase in the number of
mitochondria and chloroplasts.
State: give a specific name, value or other brief answer without explanation or calculation
The name ‘interphase’ implies a period of time
between stages and that nothing much is going on.
This is not the case!
This is when the cell is going about it’s day-to-day
‘business’ i.e. carrying out it’s programmed
functions and growing.
Imagine if cells did not have a growth phase. What
would happen to the size of daughter cells with
progressive rounds of mitosis?

10. Think: What else
would have to
stop when the
chromatin is
tightly coiled and
condensed into
chromosomes for
mitosis?
http://commons.wikimedia.org/wiki/File:Chromosome.svg

11. That’s right,
transcription can’t be
done when the DNA is
tightly coiled.
So Interphase is when
all of the cell’s genetic
instructions are
processed.
http://commons.wikimedia.org/wiki/File:Chromosome.svg

12. Extension:
http://www.flickr.com/photos/seyyed_mostafa_zamani/4266283238/

13. 2.5.4 Describe the events that occur in the four stages of mitosis
^C

17. Prophase
Metaphase
Anaphase First 3D video of mitosis.
Source forgotten, let me know if you know!
Telophase

18. Pea
MAT
http://www.flickr.com/photos/cmatsuoka/3732303102/
http://www.flickr.com/photos/zaser/2524931166/

19. People
Meet
And
Talk
http://www.flickr.com/photos/chuckp/252924532/

20. 2.5.5 Explain how mitosis produces two genetically identical nuclei
Think back to slide 3…
What happens during the
synthesis part of
interphase?

21. Synthesis
S
http://commons.wikimedia.org/wiki/File:Synthesis_cell_lifecycle.svg

22. So, the chromosomes in the nucleus have been exactly copied
See: Replication Core 3.4, AHL 7.2
During Prophase the Chromatin condenses
into the familiar X shaped chromosome,
which is actually two identical chromatids
joined at the centromere.
And then when the chromosomes
split in half during anaphase, the
identical chromatids are dragged
to opposite ends of the cell
Cytokinesis cuts the cell in half, with one set of
duplicate DNA in one daughter cell and the
other identical set in the other daughter cell
∴ Both nuclei are ∴ Both nuclei are
identical identical
http://www.flickr.com/photos/wellcomeimages/5987498303/http://w
ww.flickr.com/photos/thejcb/4117622551/

23. 2.5.6 State that growth, embryonic development, tissue repair and asexual reproduction involve
mitosis
Any time new cells are required,
mitosis is required:
• Growth: An 18 year old has many more cells than an 18
month old!
• Embryonic development: You start as a zygote, one cell!
• Tissue repair: Burnt, bashed, cut or eaten; dead or lost
cells need to be replaced.
• Asexual reproduction: In eukaryotes only
remember: what do prokaryotes do?

24. Make your own Play Doh™
or Plasticine™ mitosis model
to further your understanding
make your own
playdough!
http://www.flickr.com/search/?l=cc&mt=all&adv=1&w=all&q=mitosis&m=text

25. Further information:
Three of the best sites for
IB-specific Biology
information. The top link
takes you to the PPT by
Stephen Taylor