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Introduction to Genetics. Genetics. The scientific study of heredity . Example: Geneticist, Genetic counselor, Genetics researcher. Heredity. The passing of traits from parent to offspring Example: Both of your parents have brown hair and so do you
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Genetics • The scientific study of heredity. • Example: Geneticist, Genetic counselor, Genetics researcher
Heredity • The passing of traits from parent to offspring • Example: Both of your parents have brown hair and so do you • * Heredity is not always this simple. You might have blue eyes even though both of your parents have brown eyes
Traits • Distinguishing qualities that can be passed from one generation to the next • Examples: hair color, eye color
Genes • The set of instructions that determine what traits an offspring has. • There are at least two genes for every trait • Example: Some people inherit the genes (instructions) for making dimples.Genes are found in the base sequence of the DNA (the letters)!
Alleles • Different versions of the same gene • Each person only has two alleles, even if there are more possible • Example: alleles for eye color would include brown, blue, green, grey, hazel
Dominant Trait • A dominant trait is observed when at least one dominant allele is inherited • BB or Bb • A dominant allele is written as a CAPITAL letter • Example: Brown eye color (B) is dominant over blue eye color (b).
Recessive Trait • When a trait is recessive it is only visible when two recessive alleles are inherited (bb) • A recessive allele is written as a lower case letter • Example: Blonde hair color (b) is recessive.
Thedominant trait is stronger, more powerful than the recessive trait. • Therecessive trait is weaker than the dominant trait. • The dominant trait overpowers the weaker recessive trait when the two are together.
Genotype • The inherited combination of alleles (Represented by letters) • Example: DD or Dd or dd • Can you see an organism’s genotype?
Phenotype • The organisms inherited appearance • Example: straight, wavy, or curly hair • Can you see an organism’s phenotype?
Applying what you learned! • If T=tall and t=short, what will be the organism’s phenotype? • TT • Tt • tt
Homozygous • Having two alleles that are the same for a gene • “Purebred” or “true-breeding” • Examples: BB or bb
Heterozygous • Having two alleles that are different for a gene • “hybrid” • Example: Bb or Pp
Homozygous or Heterozygous? • 1.SS • 2.Bb • 3.pp • 4.Tt • 5.RR • 6.ff • 1.homozygous • 2.heterozygous • 3.homozygous • 4.heterozygous • 5.homozygous • 6. homozygous