Intro to Genetics

Human Traits  How do we get our traits? Why are we tall, short, blonde? What makes us us?

Genetics  Every living thing – plant or animal, microbe or human being – has a set of characteristics inherited from its parent or parents.  Since the beginning of recorded history, people have wanted to understand how inheritance is passed from generation to generation

What is Genetics?  Genetics - the branch of biology that studies heredity  Heredity - the passing on of traits from parents to offspring  Traits - Characteristics that are inherited

Mendelian Genetics  Gregor Mendel, an Austrian monk, made important discoveries about inherited traits  Mendel was born in 1822 in what is now the Czech republic  He studied to be a priest and spent several years studying science and math

Mendel  Mendel spent the 14 years of his life working in the local monastery and teaching high school  While there, Mendel was in charge of gardening and spent most of his time tending to and studying the plants around him

Observations  Mendel observed seven traits that are easily recognized and only occur in two forms  Flower color: purple or white  Flower position: axil or terminal  Seed color: yellow or green  Seed shape: round or wrinkled  Pod shape: inflated or constricted  Pod color: yellow or green  Stem length: long or short

Why these traits?  Were these genetic or environmental factors?

Experiments  Mendel performed experiments with pea plants by forcing plants with different traits to pollinate each other  The experiments are called genetic crosses

Offspring  Mendel noticed that many times the second generation plants showed different traits from the parents

Pea Plants  Pea plants reproduce sexually, meaning they have both male and female sex cells  Gamete cell= sex cell.  half of the chromosomes  Somatic cell= the rest of the cells in your body.  full set of chromosomes

Offspring  Phenotype = the physical characteristics of an organism. Ex. Blue eyes or brown eyes.  Genotype = the gene combination of an organism that determines its phenotype.

Alleles  Alleles = the gene form for each variation of a trait. (Written as capital or lower case letter ex. B or b )  Dominant = the observable trait that masks a recessive form of a trait. (Written as a capital letter)  Recessive = a hidden trait that is masked by a dominant trait but carried in the genes (Written as a lower case letter)

Alleles  Homozygous= when the two alleles for a trait are the same. Ex. BB or bb  Heterozygous= when the two alleles for a trait are not the same. Ex. Bb

Chromosome – gene – allele - trait