DNA 101 – Lecture for Kids!
Lesson 1: What are genes?
Your body is made up of 50 trillion cells. Cells come in many different varieties, with many different functions. But inside almost every cell is a nucleus containing 99.9% of your genes, and mitochondria containing a few more genes. All told, you have nearly 20,000 genes.
Your gene is a small part of a long molecule called DNA or deoxyribonucleic acid. If you line up all of the DNA containing of all your genes, it will measure 6 feet long! But it’s coiled so tightly that it fits in just 1 cell nucleus.
DNA is a double stranded molecule composed of sugar, phosphate and four different bases: Adenine, Thymine, Cytosine, and Guanine. These bases spell out the language known as the genetic code.
The number and order of these 4 bases determine for example, whether you are a chimp, a cow, a banana, or a human. Most genes are recipes for making specific proteins. These recipes are passed out from parents to children, from generation to generation.
When someone says, “You have your father’s hair”, what they mean is, “You appear to have inherited a gene or genes from you father that makes a protein that instructs your hair follicle cells to produce hair that curls like your father’s”. But they usually opt for the shorter version.
Genes tell the cell how to function and what traits to express. Most specifically, gene regulate to turn different genes to turn and off in different cell to control cell function.
The long molecules of DNA containing you genes are organized into pieces called chromosomes. Different species have different numbers of chromosomes.
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Humans usually have 46 chromosomes. Two sets of 23, more simply, 23 pairs of chromosomes.
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Chimpanzees has two sets of 24 or 24 pairs of chromosomes.
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Rhesus monkeys have 21 pairs of chromosomes.
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Cows have 30 pairs of chromosomes.
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Chicken have 39 pairs.
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Fruit flies have 4 pairs and
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bananas have 11 pairs.
So, what percentage of the DNA in your chromosome do you share with other species?
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You share 93% of your DNA with a Rhesus monkey.
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And 98.5% with our friend, chimpanzee.
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How about with other humans? 99.5%
So, what makes us different from one another?
Well, for one thing, SNPs!
