pulling the wool over mitosis... or, how you can help students understand the difference between...
TRANSCRIPT
![Page 1: Pulling the Wool Over Mitosis... or, how you can help students understand the difference between chromosomes and chromatin](https://reader031.vdocuments.mx/reader031/viewer/2022032703/56649cf95503460f949cabaa/html5/thumbnails/1.jpg)
Pulling the Wool Over Mitosis
. . . or, how you
can help students understand the difference between chromosomes and chromatin.
![Page 2: Pulling the Wool Over Mitosis... or, how you can help students understand the difference between chromosomes and chromatin](https://reader031.vdocuments.mx/reader031/viewer/2022032703/56649cf95503460f949cabaa/html5/thumbnails/2.jpg)
We have two ideas about DNA
Think DNA ...
… you see a double helix.
![Page 3: Pulling the Wool Over Mitosis... or, how you can help students understand the difference between chromosomes and chromatin](https://reader031.vdocuments.mx/reader031/viewer/2022032703/56649cf95503460f949cabaa/html5/thumbnails/3.jpg)
The other picture of DNA . . .
Think “chromosome” and you see X’s (and an occasional Y).
![Page 4: Pulling the Wool Over Mitosis... or, how you can help students understand the difference between chromosomes and chromatin](https://reader031.vdocuments.mx/reader031/viewer/2022032703/56649cf95503460f949cabaa/html5/thumbnails/4.jpg)
Chromosomes
• DNA is not neatly wrapped in chromosomes during most of the cell cycle
• Only during mitosis does DNA condense into “chromosomes.”
![Page 5: Pulling the Wool Over Mitosis... or, how you can help students understand the difference between chromosomes and chromatin](https://reader031.vdocuments.mx/reader031/viewer/2022032703/56649cf95503460f949cabaa/html5/thumbnails/5.jpg)
Chromatin
During the rest of the cell cycle, DNA is in the uncoiled or CHROMATIN form.
![Page 6: Pulling the Wool Over Mitosis... or, how you can help students understand the difference between chromosomes and chromatin](https://reader031.vdocuments.mx/reader031/viewer/2022032703/56649cf95503460f949cabaa/html5/thumbnails/6.jpg)
Chromatin Model
Teased sheep’s wool can model chromatin in a cell
This is the wool as purchased from a crafts store
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Wool-as-chromatin
Pull the wool loosely apart ...
… explain that during Interphase DNA must be loose in order to be transcribed into RNA.
![Page 8: Pulling the Wool Over Mitosis... or, how you can help students understand the difference between chromosomes and chromatin](https://reader031.vdocuments.mx/reader031/viewer/2022032703/56649cf95503460f949cabaa/html5/thumbnails/8.jpg)
Chromatin Condensing
In prophase, the chromatin must condense into chromosomes.
In this model, the “chromatin” is spun into a thread.
![Page 9: Pulling the Wool Over Mitosis... or, how you can help students understand the difference between chromosomes and chromatin](https://reader031.vdocuments.mx/reader031/viewer/2022032703/56649cf95503460f949cabaa/html5/thumbnails/9.jpg)
Chromosome Taking Shape
As you twirl the fibers between your fingers, the “chromosome” takes shape.
Limitation: Here many fibers form one “chromosome.” In a cell, one long DNA molecule condenses to form one single chromosome.
![Page 10: Pulling the Wool Over Mitosis... or, how you can help students understand the difference between chromosomes and chromatin](https://reader031.vdocuments.mx/reader031/viewer/2022032703/56649cf95503460f949cabaa/html5/thumbnails/10.jpg)
Chromosomes Coil
As you continue spinning, the “chromosome” will coil and supercoil on itself.
Limitation: This model leaves out histone proteins and the specific levels of coiling and supercoiling.
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chromatin
supercoiling
condensing
![Page 12: Pulling the Wool Over Mitosis... or, how you can help students understand the difference between chromosomes and chromatin](https://reader031.vdocuments.mx/reader031/viewer/2022032703/56649cf95503460f949cabaa/html5/thumbnails/12.jpg)
Credits and acknowledgements
http://www.biotec.or.th/Genome/chromosome.JPG
http://www.efa.org/images/research/chromosome.gif
http://www.gifs.net/animate/webl2.htm