Introduction to Genetics Important words to know

Genetics Study of heredity Studies the way in which genetic/hereditary information is passed on from parents to offspring

Fertilization During sexual reproduction, when a sperm and egg meet Produces a new cell, with some DNA from the mom and some from the dad

Gametes Sex cells Sperm Egg

True-breeding Means self-pollinate Ex: some plants have “male” and “female” sex organs, so can produce offspring identical to themselves Ex: pea plant, apricot, avocado, grapes

Trait A specific characteristic Varies from one individual to another Ex: eye color, human height, seed color, plant height

Chromosomes Contain hereditary information (DNA)

Gene Specific unit of hereditary material located on a chromosomes Genes code for specific traits

Alleles Different forms of a gene Ex: The gene controlling hair color exists as an allele for blond hair or an allele for brown hair. Ex: in plants, the gene controlling height either exists as an allele for tallness or an allele for shortness.

Principle of Dominance Some alleles are dominant and some alleles are recessive.

Dominant vs. Recessive Alleles Dominant Alleles Recessive Alleles An organism with a dominant allele for trait will always exhibit that trait. Dominant expressed by capital letter An organism with a recessive allele for a trait will show that trait if the dominant allele is not present. Recessive expressed by lower case letter In pea plants, the alleles for height is either T or t. Which is the recessive allele? If we were looking at human eye color, pick a letter to represent eye color. Now show the difference between brown (dominant) and blue (recessive) alleles?

Hybrid Offspring from parents with different traits Ex: yellow corn and white corn offspring with both colors Offspring has the DNA from both parents