Text only version
Lots of things
in our homes and schools and workplaces -- and in wild and natural places -- can cause harm sometimes. Why "sometimes"? The harm may depend on who you are as well as what you do, what you are exposed to, and when.
|Big, muscular people look as if they can
resist anything. But they can have allergies or asthma, or be injured by chemicals, too. And the bigger they come, the more skin the sun can burn!|
Most of us, for example, can get sunburned on a bright day. Your reaction will be greater if you are outside, without much on, for a long time. Your reaction will be less if you cover your exposed skin with lots of sun screen. How badly you burn can depend on your age and previous exposure. (Babies and toddlers need a lot more protection.) Finally, if one or both of your parents burn very easily, they may have passed that sensitivity to you in your genes.
Designer Genes -- They're the Boss!
Genes are the instructions -- the marching orders -- that direct our growth, what we look like, and how we react to things in our world, or environment.
Each human - whether infant, child, teen or adult - has 70,000 pairs of these orders, or genes. They tell our bodies' cells what to be and how to behave.
Do you remember transformer toys? You twisted them one way and they were space ships. You twisted them another way and they became robot warriors. Well, under the genes' orders, the cells become the ultimate in
transformer robots. The genes instruct our original dab of cells, as
they divide, to become different - muscle, bone, lung, or brain
cells, or part of a toe. As a result of what the cells become and do, we grow. And we stand and run and catch footballs
and dance - more or less with grace and skill.
We breathe. We think!
Our genes, or instructions, are coded on short segments of a long chemical chain called DNA. It is in the center of each cell of our bodies. Think of genes as information bits paired along two spiraling strands of this chemical - like snap-together beads in two long, connected strings of DNA.
Every human has the same number and set of genes, so you might think we would all be exactly the same. But the genes themselves vary a lot or a little, just as people do - and as animals do. That's why we do. For example, everyone has a
pair of genes for eye color but one variation instructs the eyes to be blue while other variations order green or brown.
|The complete package of genes for an animal - what makes a dog a dog - is called its genome. These packages or genomes are why people give birth to babies, dogs to puppies, and cats to kittens.|
Many of the genes in other animals
are similar to those in humans. After
all, people and animals, like our
dogs, all have to do certain things, like digesting food, so we need a similar gene for that. When we are loyal, frisky and bright-eyed - and tip over garbage cans - maybe it's those shared genes?
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