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Genetics

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The members of this family tree are related and so they share certain similar characteristics. So why dont all family members look exactly alike?

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People are similar, but not identical, to their parents or each other. The differences in a species are called variation. Variation can come about for two reasons. What are they?

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People inherit characteristics from both of their parents These are called inherited variations. Other characteristics are affected a person surroundings. These are called environmental variations.

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Can you think of other environmental and inherited variations? EnvironmentalInherited

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How does a builder know what kind of building to build? How does grandma know how to work the DVD player?

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How do our eyes know to be blue? How do our heart cells know to keep beating?

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Genetic material (DNA) contains the instructions used by living things. Genetic material is found in the nucleus of cells.

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If we look closer into the nucleus we can actually see the genetic material as chromosomes. Although chromosomes appear short and fat, they are actually very long strands that are tightly coiled.

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When we look closer still, we find that chromosomes are complex structures made of molecules of deoxyribonucleic acid (DNA ).

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DNA contains all the information required to build a living organism. Each chromosome is made up of two long DNA molecules. The two molecules are twisted around each other forming a double helix.

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Within the long strands of DNA we find genes. A gene is a section of the DNA that contains the code for a specific inherited trait. Every person is unique because they have different combinations of genes.

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An allele is an alternative form of a gene. Person #1 may have the Brown allele of the eye colour gene. Person #2 may have the Blue allele of the eye colour gene.

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Karls DNA Hollys DNA Eye Colour Gene

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