Genetics

 The members of this family tree are related and so they share certain similar characteristics. So why don’t all family members look exactly alike?

 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?

 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.

 Can you think of other environmental and inherited variations? EnvironmentalInherited

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

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

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

 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.

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

 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.

 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.

 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.

 Karl’s DNA  Holly’s DNA Eye Colour Gene

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