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