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Chapter 2 . Lesson 2 Traits and Heredity. What is heredity?. Heredity : the passing down of traits from parents to offspring. Inherited trait: a trait that an offspring receives from its parents. (dimples, hair and eye color, facial features, even a laugh.
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Chapter 2 Lesson 2 Traits and Heredity
What is heredity? • Heredity : the passing down of traits from parents to offspring. • Inherited trait: a trait that an offspring receives from its parents. (dimples, hair and eye color, facial features, even a laugh. • Instinct: a way of acting or behaving that an animal is born with and does not have to learn. (a spider spinning a web)
Dominant Trait: A strong trait passed along by a parent to an offspring. (Both parents have brown eyes, the child is likely to have brown eyes.) Recessive Trait: If both parents of a child carry the dominant and recessive genes, there is a 25% chance that the child will develop the recessive trait. How are traits inherited?
Genes: Chromosomes, contain the DNA codes for all the traits an organism inherits. How are traits inherited?
How do we trace inherited traits? • Gregor Mendel: monk who studied and discovered the basic principles of heredity. Mendel discovered that for every trait there is a dominant form and a recessive form.
How do we trace inherited traits? • A pedigree is a chart used to trace the history of traits in a family.
How do we trace inherited traits? • Carrier: the individual who has inherited the gene for a trait, but does not physically show the trait.
Decoding the Human BodyTime for Kids Article • Have you ever wondered how a chicken egg manages to grow into a chicken and not a frog? Or how a frog egg produces a frog and not a python? The answers lie in their genes, tiny sets of chemical instructions in every cell of every creature that contain its recipe. The recipe for a human being is contained in the 80,000 genes we inherit from our parents. These genes have the instructions that not only make us human but also determine things like skin color and the shape of our nose.
Decoding the Human Body • Last week Craig Venter, the lead scientist at Celera Corporation in Maryland, announced that his team had cracked the chemical code for every human gene. • This breakthrough is likely to lead to great medical advances. Knowing detailed information about human genes could help millions of people who suffer from illnesses caused by mistakes in their gene code. They could someday undergo genetic treatments to correct the problems. Doctors may also be able to detect and prevent illnesses like cancer and heart disease, which are linked to certain genes.
Decoding the Human Body • Scientists have years to go before they can pinpoint the function of every gene. "We're assembling one of the biggest jigsaw puzzles ever imaginable," said Venter. • The Code of LifeGenes are made of a special chemical called DNA. It is shaped like a very tiny, twisted ladder. The rungs of the ladder are made of four chemicals. These chemicals can appear in an almost endless variety of patterns. Each pattern forms the instruction, or code, for a specific component of the human body.
What to do:Tracking Traits! 1. Begin by drawing a family tree with your child. Start with your child's great-grandparents, or even great-great-grandparents, if possible. Fill in as much of the tree as you can. 2. Decide on which traits to track. Hair color and eye color are obvious choices, but you could also try to trace abilities such as singing or sports, or even diseases like diabetes. What kinds of traits are not inherited? 3. On the tree, mark which family members had the traits you selected. 4. Help your child record the frequency of the trait on a graph. Try different kinds of graphing techniques, such as bar graphs or pie charts.