Dominant and Recessive Genes

1. Dominant and Recessive Genes

2. Patterns of Inheritance • Genes • Made up of DNA • Located on the Chromosomes • During Meiosis pairs of genes separate and each new cell gets one form of a gene for a specific trait. • Genes may have different forms and we call these Alleles. • Always come in pairs (two genes for each trait.)

3. Determining Inheritance • An organism recieves two genes for each trait, one from each parent. • One of these genes may be stronger or more Dominant , so it overpowers the other and shows up in the offspring. The gene not expressed is called the recessive gene. • Two forms of a gene(alleles) that are the same produce a homozygous organism. • Two forms of a gene (alleles) that are different produce a heterozygous organism.

4. Pure traits • Organisms that receive 2 of the same gene type – both dominant or both recessive will have pure traits • Ex. A cow has two genes for black color, which is dominant in some breeds. Any offspring of that animal will be black. This animal is considered homozygous with a pure dominant trait for color. • A cow that has genes for a red color is also considered pure, however because red is a recessive trait they would be considered homozygous pure with a pure recessive trait for color.

5. Hybrid trait • Organisms with two unlike genes for a certain trait are called Hybrid. • A cow with a dominant gene for black color and recessive gene for red color is considered a hybrid for that trait. • The offspring from a pure black bull bred to a pure red cow would be what?

6. Things to remember: • An organism may be Dominant in certain traits and recessive in others. • Dominant traits in one organism may be recessive traits in another organism.