What’s the difference between an allele and a gene?

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Genes control the general traits with which an organism is born, such as blood type and the color of the eyes and hair. An allele is a type of gene which defines the possible variations of those traits in that specific organism.

Children inherit two sets of chromosomes, one from each parent. These chromosomes are found in DNA strands: the double-helix spiral molecules that contain all the genetic information. DNA serves as a unique blueprint, or code, for the child’s development.

Genes are found in certain sections of the DNA strand. There’s a section for hair color, another for eye color, another for blood type, and so on. Each of these sections contains two alleles (one from each parent’s chromosome), and here’s where the variations occur: the gene in the eye-color section may have one allele for blue eyes and another for brown eyes.

How do the genes decide which allele to choose? Alleles can be dominant or recessive. Brown eyes are a dominant trait, so if even one brown-eyed allele is present, the child will always have brown eyes. Blue eyes are a recessive trait, so a child will have blue eyes only if both parents’ alleles contain that code.

So, your genes determine that you’ll have hair and blood and eyes. The alleles are specialized genes that determine the unique qualities of these body parts.

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