Nan's No-Tech Genetics
by: Nan
What are genes?
Genes are things that tell the body how to make a living being. Each gene only tells a little bit about how to make a living thing. Every living thing needs a lot of different genes.
Worms have genes. Humans have genes. Birds have genes. From here on, we'll be using birds as our example.
Since genes are tiny, we'll picture them as little dots. Where do the little dots live? On chromosomes. We'll picture them as lines. (The genes and chromosomes really do look like dots and lines.) What do chromosomes do? They hold the genes. Lots of gene-dots, in a row, make up the chromosome.
Do these things actually exist? You bet. Where? In cells. Cells are tiny bits of living matter. Genes and chromosomes are chemicals that live in the cells.
All chromosomes come in pairs. This is very important. Almost every gene has a partner, on the other chromosome. The gene and its partner each tell the same little bit about how to make a bird.
Both genes in a pair tell about the same little bit, such as how many heads or eyes the bird should have.
But both genes in a pair might not have the same ideas about how it should be. The genes in a pair might disagree.
What happens when gene pairs disagree? There are several different ways they can resolve their differences. Some genes win all the time. They are called dominant genes.
Some genes make a compromise. These are called semi-dominant genes.
Some genes just lose if there's any disagreement. They are called recessive genes. We might not be able to see any effect from a recessive gene, if it has a dominant partner. For instance, a bird would look green if it had one (dominant) gene saying it should be green and one (recessive) gene saying it should be blue. You might never know it had the blue gene.
Some genes win most arguements but lose a few. Green is a dominant gene, when it's disagreeing with blue. But grey is dominant over green. Kind of like saying the grey gene is "more dominant".
More! I want more no-tech genetics!
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