Genetics

What is Genetics? The scientific study of heredity.

WHAT IS HEREDITY? Heredity is the passing of traits* from parent to offspring. *A trait is a characteristic that an organism can pass on to its offspring through its genes – such as eye color or fur color.

Who do we thank for studying genetics?

GREGOR MENDEL In the mid nineteenth century, a priest named Gregor Mendel tended a garden in a European monastery. His experiments in the garden would one day revolutionize the study of heredity. Known as the father of Genetics.

Mendel studied thousands of pea plants. He noticed that there were many different traits among the plants: some plants were tall some were short some had purple flowers some had white flowers some had yellow peas some had green peas Etc...

Gregor Mendel He noticed that these traits were passed down from the parent plant. He decided to cross-breed certain pea plants to see what the new plant would look like (meaning, what traits the new plant would have).

Genes Genes are the set of information that controls a trait. Genes are part of your DNA. Your DNA is found in your cells. Located on a “twisted ladder” inside each cell.

Alleles Alleles are different forms of genes. –For Example: When Mendel was studying pea plants, he found that there were two alleles for every gene. Stem Height: one allele was tall stem; one allele was short stem. Every living organism inherits two alleles for each gene: one from the father and one from the mother.

Dominant and Recessive Traits Dominant Trait: An allele whose trait always shows up in the organism. Recessive Trait: An allele whose trait is masked or hidden when a dominant allele is present.

Symbols for Alleles Letters are used to represent alleles. A dominant allele is represented by a CAPITAL letter, A recessive allele is represented by a lowercase letter. Trait: color of fur F: (black fur) dominant allele f: (white fur) recessive allele

Predicting Heredity To determine the chances of inheriting a given trait, scientists use Punnett squares and symbols to represent the genes. is aThis Punnett Square

Punnett Squares TtTtTt The genes from one parent go here. The genes from the other parent go here.

Example – Dilute Gene Chestnut Palomino Cremello Bay Buckskin Perlino dd Dd DD

dd D d DdDd dddd Dd = Palomino or Buckskin dd = Bay or Chestnut 50/50 Chance of getting a dilute- colored horse

Dd D d DDDd Dddd Dd = Palomino or Buckskin dd = Bay or Chestnut 75% Chance of getting a dilute- colored horse DD = Cremello or Perlino

Dd D D DDDd DDdD 100% Chance of getting a dilute- colored horse DD = Palomino or Buckskin But what was my REAL goal?

dd D D DdDd DddD Dd = Palomino or Buckskin 100% Chance of getting a Palomino or Buckskin!

Palomino: Buckskin: Perlino: