In this week’s newsletter, we’re going to talk about chromosomes. While they seem somewhat abstract, these wound up pieces of DNA are very real. It’s just that they’re small so it’s hard to visualize them in every cell. The coolest thing about chromosomes is that if you learn to read them, you could (in theory), make a human. Or a dog. Or a horse. Or any other living thing. They are the instruction manuals that tell enzymes how to make a living organism.
So, What Exactly Are Chromosomes?
You often see chromosomes drawn as X’s and Y’s, but that’s just an easy way to denote them in writing and kind of matches up to their shape. In actuality, the best way to picture a chromosome is to first think of DNA. Zoom out and that twisted ladder becomes a strand. We don’t want it to tangle, so let’s wrap it around some proteins (called histones) until it looks like a string of pearls. Keep winding and condensing the DNA down (with the help condensin) and you end up with a chromosome.
During the normal life cycle of a cell, the DNA is unwound so that sections of it can be copied to make proteins; but cell replication requires the cell to do some packing. If you think it’s difficult to move without putting all your stuff into boxes, imagine how the cell must feel if it had to divide and make a copy of itself, all the while dealing with long strands of nucleic acids. What a mess!
Mix N’ Match
While all organisms share conserved sequences of genes, these pieces are mostly used to do basic cell processes. There’s a wide range of chromosome combinations throughout the evolutionary tree. Plants for example, are polyploidy, in that they have more than 2 sets of complete chromosomes. Humans are diploid, our chromosomes come in pairs. Mismatched chromosome pairs result in non-viable fetuses or in the case of the mule (63 chromosomes that come from a combination of 64 horse chromosomes and 62 donkey chromosomes), infertile offspring.
Get Yourself Some Chromosomes
The only time you can mix and match chromosomes and end up looking great is at our atelier. We’ve got chromosome earrings to match with necklaces and even a ring! Purchase these pieces for yourself or for a friend. They also make a great gift for chromosomal disorder researchers, mule lovers, geneticists, and starry-eyed pre-med students.
written by Science with Evie