Do you look exactly like either one of your parents Do you look exactly like either one of your parents? What about your siblings? Why is this & how do you explain it???

Summing up Mendel’s Laws The Key Terms!!

What is Genetics? Study of heredity from generation to generation AND variation of organisms Heredity – passing of characteristics: parents → offspring Traits – characteristics received by offspring (Ex: color, size)

Somatic Cells vs. Gametes A quick review of cells… Somatic Cells vs. Gametes

A quick review of reproduction Sexual reproduction – Sex cells (gametes) from male & female come together Sperm Egg Fertilization – fusion of gametes; individual traits passed to fertilized cell (zygote)

DNA in sperm & egg cells carry genes on chromosomes Genes – sections of DNA that code for traits (proteins); come in different forms called alleles Allele – located on 2 different copies of a chromosome, 1 inherited from mother, 1 from father Examples: Plant Height – Tall/Short Plant Color - Purple/White

Law of Dominance Dominant allele – masks recessive trait Recessive allele – trait that can be masked Example: Can you roll your tongue? Tongue rollers are dominant. Let’s symbolize the tongue rolling trait using a letter code – let’s use “T.” If dominant is T Then recessive must be t

Genotypes and Phenotypes Letter codes can be joined together in various combinations…what are they? TT – tongue rollers Tt – tongue rollers tt – non-tongue rollers Genotype: gene combos Phenotype: observable character-isitics

How do we categorize these combinations??? Homozygous – same 2 alleles → recessive alleles are ALWAYS homozygous TT, tt Heterozygous – different alleles Tt

Mendel’s Laws Law of Segregation – Because each organism has 2 alleles → TWO different types gametes can be produced During fertilization, gametes randomly pair → produce combinations of alleles

Mendel’s Laws cont… Law of Independent Assortment Genes for different traits inherited independently of each other Genes separate and recombine This accounts for variation in genotypes/phenotypes!