Dress is thrifted | socks are from a market stall | shoes are c/o Yeswalker | sweater is thrifted | bag is from Asos
When I moved out of home, I left about two-thirds of my clothes at my parent's house. Whenever I go back to visit, I also get to rediscover all these old clothes! Going through my old wardrobe is like visiting my own personal (free) thrift shop, and lets me refresh my wardrobe every few months without having a buy a thing. This cropped sweater is a gem that I've had for years, originally thrifted. And I just got this dress for a couple of dollars at an op-shop the other day, too! I'm really enjoying getting into thrifting again, though it's helped that I've been finding the most awesome stuff lately.
Now that you all know how cells, DNA and chromosomes work (if not, read part 1 of this post first), let's talk about what genes are. Inherited your mum's thick hair or your dad's big nose? It's all got to do with your genes, baby.
The "gene" is the basic unit of inheritance - the stuff being passed down from generation to generation. And a gene is actually just a section of DNA, somewhere on one of your chromosomes, that gives your cells instructions to make a particular protein. Genes that make globin, for example (part of your blood) look like this, and the protein it makes (a stylized image, of course) looks like this.
(If you've forgotten what the letters stand for, read part 1 first.)
So your cells make proteins by reading genes.
Your cells are able to read the DNA sequence of your genes, which each have a little "promoter" - a specific DNA sequence - to let the cell know that it is there and ready to be made into protein. When the cell knows that the time is right (and there is a whole lot of complex signalling going on to tell the cell when the time is right, that I'm not going to go into here), it uses what is called an "RNA polymerase" to transcribe the DNA into a similar molecule called mRNA.
mRNA also uses "bases" and they are just the "opposite" of what is written on the DNA, with T being substituted for a very similar base called uracil ("U").
When mRNA is made, it pairs up with one strand of DNA, and places a U wherever there is an A, an A wherever there is a T, a C wherever there is a G and a G wherever there is a C.
The mRNA is just a code for making proteins - and each group of three bases makes a particular amino acid, which is the basic unit of proteins.
For example, the code "UUU" makes the amino acid "phenylalanine" in the protein.
If you can imagine that all the DNA in your cell is a whole book of instructions, making mRNA is essentially like copying out just one instruction from one page of the book. Then the mRNA sits around in your cell, a code waiting to be translated into the language of amino acids. When it is translated into a series of amino acids, this is called a protein. The protein can then go and do useful stuff - like making your hair a particular colour.
Example: Red hair genes
A gene that can determine whether or not you have red hair is a sequence with the name MC1R. It is located on chromosome 16, and one particular variant has this DNA sequence.
MC1R makes a protein that attaches to hormones in cells which make skin and hair pigment, and influences the rate and type of pigment being made. We all have the MC1R gene, but if you have a particular version of this gene (meaning that the letters in the DNA are slightly different from someone with brown or blonde hair), you will have red hair! I unfortunately do not have this gene myself, and have to dye my hair red instead.
This map shows where many of the genes are on your chromosomes that are responsible for determining the thickness, colour, growth rate and curliness of your hair.
We all share a lot of the same genes with one another - you are 99.9% identical at the DNA level to any other random human on the planet. But the differences inside many of the genes, and the insanely large number of combinations that you can make out of all of them, is what makes us all individuals.
Read biochemistry basics part one here.
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