Genetic Analysis is the Key to Curing Cancer – Part #2
I’m not a doctor, nor do I play one on TV. I don’t have a medical background but I have done a lot of reading in an effort to better understand how medicine and disease work, mostly with a view to better understanding cancer.
At this point I understand only the basics. I still don’t know what I don’t know, but I have more of an understanding than when I started and that’s enough to go on. This post is more for my own benefit to test if I understand this stuff so it may read a little like a biology lesson. Here’s what I’ve pieced together.
Humans are made of cells *duh*. Roughly 10^14 or 100 trillion cells. There are different types of cells but they generally share the same traits in that they all have a membrane, a nucleus, ribosomes, chromosomes and DNA. Here’s a visual:
The DNA’s in the nucleus, but what is it? And what are genes? chromosomes? how’s it all work?
DNA is made up of 2 strands of what are called "bases" or nucleotides (A, C, G, T) arranged in a row. These bases form base pairs (A-T or G-C for example) with their opposing base in the opposite strand. Remember the movie GATTACA? Each base pair is an instruction, you’ll see why in a minute.
If you took all the instructions needed to make a human, you’d have the human genome. The human genome has about 3 billion base pairs of DNA arranged into 46 chromosomes. All of this in a tiny nucleus of each and every cell and ALL in your body replicated 100 trillion times. What’s 3 billion times 100 trillion? 10^23? Amazing so far right?
Back to the strands. Every 3 nucleotides in a strand is called a "codon" e.g. ATT or GGT etc. and there’s also a few combinations that are called "start codons" and "stop codons".
Ok so (A,C,G,T) are the possible base values and 3 positions in a codon so 4 x 4 x 4 = 64 possible codons. Each combination represents an Amino Acid but some are duplicates so instead of 64 amino acids it turns out there are only 20. Here’s a table of amino acids with the corresponding codons.
| Ala/A | GCU, GCC, GCA, GCG | Leu/L | UUA, UUG, CUU, CUC, CUA, CUG |
|---|---|---|---|
| Arg/R | CGU, CGC, CGA, CGG, AGA, AGG | Lys/K | AAA, AAG |
| Asn/N | AAU, AAC | Met/M | AUG |
| Asp/D | GAU, GAC | Phe/F | UUU, UUC |
| Cys/C | UGU, UGC | Pro/P | CCU, CCC, CCA, CCG |
| Gln/Q | CAA, CAG | Ser/S | UCU, UCC, UCA, UCG, AGU, AGC |
| Glu/E | GAA, GAG | Thr/T | ACU, ACC, ACA, ACG |
| Gly/G | GGU, GGC, GGA, GGG | Trp/W | UGG |
| His/H | CAU, CAC | Tyr/Y | UAU, UAC |
| Ile/I | AUU, AUC, AUA | Val/V | GUU, GUC, GUA, GUG |
| START | AUG | STOP | UAG, UGA, UAA |
If you took a bunch of amino acids in a string you’d have a Gene. I originally though you’d have a protein but I think it’s only the information needed to CODE for the protein. So a Gene is essentially the series of codons between the start and stop codons (I think). Hence by manipulating the genes you get different proteins and essentially a different evolution of the host.
Next up: Genes, RNA and how it DNA splits apart.
