Aim: How do your genetics play a role in the person you are today?  Do Now: What similarities do you have with your parents or siblings?  Homework:Textbook #1-5

Human Genetics

What is Heredity?  The transfer of characteristics from one generation to the next

What are Traits?  A characteristic that is determined by your genes  A pair of genes will determine the trait  Examples:  Tongue rolling  Earlobes  Widow’s Peak  Hair Whorl  Dimples

What is genetics?  The science of how traits are inherited

Where do our genes come from? We had said that a pair of genes determines which traits we will inherit from our parents Why would it be a pair of genes? Each parent provides a sex cell in order for fertilization to occur The father will provide a sperm cell that has 23 chromosomes The mother will provide an egg cell that has 23 chromosomes When these two cells merge and become one, fertilization has occurred, and as a result, the new fertilized egg has 46 chromosomes ( = 46)

23 chromosomes + 46 chromosomes 23 chromosomes

How are traits determined?  Dominant Genes – the traits that will usually appear in the individual (represented by an uppercase letter)  If an organism has a gene for blue or brown eyes, usually it will have brown eyes because in is the dominant gene  Recessive Genes – The gene hidden by the dominant gene (represented by a lowercase letter)  Blue-eyed people need two recessive genes to show the blue-eyed trait

Who is Gregor Mendel?  “Father of Genetics”  Studied pea plants  He crossed pea plants with different characteristics and studied their offspring  He was able to determine how traits get passed on from generation to generation

What is a Punnett Square?  A table that shows the possible results when the genes of two parents are crossed  It shows the probability of a trait to be expressed in the offspring BB BBBBB bBbBb B – Brown Eyes b – Blue Eyes

What is a genotype?  The genetic code or make up of the individual  Examples: BB, Bb, bb

What is a genotype?  Homozygous dominant – a pair of dominant genes (BB) – a pair of dominant genes (BB)  Homozygous recessive – a pair of recessive genes (bb)  Heterozygous or hybrid – a mixed pair of one dominant gene and one recessive gene (Bb)

What is a phenotype?  The way an organism looks or behaves  Examples: GenotypePhenotype BB Brown Hair Bb

Lets try some Punnett Squares! Examples: Examples:  BB x bb  Bb x bb  Bb x Bb  bb x bb  BB x BB  BB x Bb B = Brown Eyes b = Blue Eyes What we are looking for: 1.Genotypes 2.Phenotypes 3.Percentage Brown eyes 4.Percentage Blue Eyes