How and why we get cancer as explained to 8 year old Sascha by Darren Saunders, Associate professor, UNSW and secretary of Science and Technology Australia. Note Darren's final sentence - "Importantly, we can almost never say for sure why an individual person has cancer." : theconversation.com/curious...
Check out the amazing 3 minute video containing two animations, illustrating how our uncoiled DNA (about 2 metres/6 feet long) is packed so it can fit within our cells and how our 3 billion base pairs of DNA are copied - which takes just one hour! youtube.com/watch?time_cont...
Copying all that genetic information so rapidly, copy errors creep in all the time - hence the importance of TP53 'the guardian of the genome': ghr.nlm.nih.gov/gene/TP53 and other error detection and correction mechanisms.
Interestingly, the animations were made at the Walter and Eliza Hall Institute of Medical Research - where landmark research discovery eventually led to the development of Venetoclax!wehi.edu.au/research-resear...
Our lymphocytes (and hence our CLL cells) are among the smallest of our cells at about 7 microns in diameter (about one tenth of a hair's thickness). The largest cell - a human egg cell, is barely visible to the unaided human eye and about 15 times wider, just about the width of a strand of our hair.
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The video however contains one statement that is incorrect and could lead to confusion. The incorrect statement is "Chromosomes are not always present. They form around the time cells divide when the two copies of the cells DNA need to be separated." That is incorrect! Within a given human cell (except for mature erythrocytes and a few other cell types) chromosomes are always present, they are just not condensed, and therefore not visible in the light microscope. The chromosomes condense and become visible in the light microscope during the prophase stage of the cell cycle and then unwind during telophase after cell division, but they are still chromosomes, all 46 of them, well, in my case with Trisomy12, all 47 of them in my CLL B cells. 😉
Thanks for clarifying about chromosomes. They could have better stated the situation as "chromosomes are not always visually obvious. They become obvious around the time cells divide..."
This link includes a brilliant illustration of how DNA is folded into one chromosome:
It also provides a much easier to visualise example of how effective this packaging is - "akin to taking a rope as long as a football field and compacting it down to less than half an inch."
WEHI is a gift to humanity! I feel bad even wishing they'd do more, they've done so much already.
Unfortunately for those of us with Trisomy 12 (or other trisomies), I have not seen a good video explanation of trisomy for the average person. On the internet, there's a ton about Trisomy 21 (Down Syndrome).
But the gist is that when the cell divides and doubles the number of chromosomes, for some reason, 1 chromosome fails to find it's counterpart. Typically, one cell will then have 3 copies of that chromosome, and the other cell will have only 1 copy of it. The one with 1 copy usually dies. Heck, cells with 3 copies of most chromosomes die - that's the weird thing. In B-Cells, 3 copies of 12 seem to survive for some reason. I'm sure there's a reason.
The closest thing WEHI has on it is this short video about mitosis - a combination of real video of a real cell dividing, and animation of some parts that don't show up under a microscope:
Something goes wrong in metaphase, I believe, and one cell gets an extra copy, and the other gets one less. The animation shows microtubules pulling the pairs apart. I imagine that a microtuble loses its grip or something.
There's this Biology Crash Course from back in 2012 that talks about normal metaphase in mitosos with some with low quality animation. Metaphase starts at about 5:30 in the video:
I learned to touch type in my final high school year in lunch time courses, put on by a very future minded teacher.
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