“Why We Look the Way We Do” Heredity and Genetics “Why We Look the Way We Do”

What is Heredity? Heredity = the passing on of traits from one generation to the next.

What is a Trait? A trait is a specific characteristic that is unique. Traits affect the way we look Traits affect how our bodies function Traits are inherited Examples are hair color, eye color, height, etc.

Where Do Traits Come From? Factors that make up an individual come from both parents. The trait information is passed on from generation to generation in the form of genes.

What are Genes? A gene is a specific location on a chromosome that controls a certain trait.

Karyotype All of the chromosomes are organized in homologous pairs (one from each parent)

Where Do Genes Come From? An individual needs 2 genes for each trait – one gene from each parent. This gene pair is called an allele. One gene comes from the sperm cell (from the Father) One gene comes from the egg cell (from the Mother)

What Kinds of Traits Are There? Traits are either Dominant or Recessive.

Dominant Trait A dominant trait is a trait that is always expressed, or shown. Examples are brown hair, brown eyes, right handed Whenever dominant is present in the genes, the trait is seen

Recessive Trait A recessive trait is a trait that is covered up or seems to disappear. Examples are blonde hair, blue eyes, left handed Need 2 recessives in order to see trait

What is Genotype? Genotype: is the genetic make up for a trait. Example: Homozygous brown; BB = pure brown: (both genes are the same)

What is Phenotype? Phenotype is the way that we look or appear. Example: brown eyes, blonde hair, tall

HOW DO WE KNOW ALL OF THIS?

GREGOR MENDEL: the father of modern Genetics

What is Mendelian Genetics? Gregor Mendel was an Augustinian monk who lived in the late 19th century and, through studying peas, developed the basis for the science of Genetics still used today. https://www.youtube.com/watch?v=6OPJnO9W_rQ

How Do We Predict Offspring? A Punnett Square is a way to show the possible combinations of genes that offspring of parents could have.

Punnett Square