Notes: Genetics p. 46-47 Genetics is the Scientific Study of Heredity

What is Heredity? Heredity Offspring The passing of traits from parents to offspring Offspring The product of reproduction A new organism produced by 1 or more parents

Heredity Activity http://www.phschool.com/atschool/california/science_explorer/life_science/Student_Area/FLS_SC3_ACT_index.html

Homework Family Tree (pg. 75) Due Wednesday 6/7/06 Survey your family and their traits Use traits from Heredity Activity

Dominant Trait Recessive Trait Free earlobes Attached earlobes Hair on fingers No hair on fingers Widow's peak No widow's peak Curly hair Straight hair Cleft chin Smooth chin Smile dimples No smile dimples

What is a Trait? Trait a genetically inherited feature of an organism (example. Eye color) Individual factors control the traits that an offspring will have

What are genes? Genes The factors that control traits The different forms of a gene are called alleles

Alleles Allele any one of a number of viable DNA codings of the same gene occupying a certain position on a chromosome Dominant allele Alleles that ALWAYS show up in the organism Recessive allele Alleles that are masked (hidden) whenever the dominant allele is present

Who is Gregor Mendel? Gregor Mendel “Father of Genetics” Young European priest Began the study of heredity and genetics using his pea plants Through experimentation Mendel discovered that one inheritable trait would always be dominant to its recessive alternative. Later known as Mendelian genetics

Mendel’s Experiment

Mendel’s Pea Plants Parent generation – purebred generation plants F1 generation – 1st filial generation - hybrid offspring of purebred P generation plants F2 generation – 2nd filial generation – hybrid offspring of the hybrid F1 generation plants

Mendel’s Pea Plants (continued) Parent generation – Tall pea plant (TT) x Short pea plant (tt) F1 generation – Tall pea plant (Tt) x Tall (Tt) pea plant F2 generation – Tall pea plant(TT)/Tall pea plant (Tt)/ Tall pea plant (Tt)/Short pea plant (tt)

Some New Vocabulary Filial - comes from the Latin word “filius” meaning son of Purebred – pure; same traits (Ex. Tall (TT) x Short (tt)) Hybrid – mixed; different traits (Ex. Tt x (tt)

Example 1 B = dominant = black fur = BB or Bb B = recessive = white fur = bb Male BB x female bb b b B Bb Bb 4/4 = black fur B Bb Bb 100% black fur

Example 2 B = dominant = black fur = BB or Bb B = recessive = white fur = bb Male Bb x female bb b b B Bb Bb 2/4 = ½ black fur b bb bb 2/4 = ½ white fur 50% black fur & 50% white fur

Dominant or Recessive? Tt BB qq Gg Rr Ff SS

Genotypes and Pheotypes Genotypes are genetic traits that are not visible The letters (example. TT, Tt, tt) Phenotypes are the traits that are visible; dealing with physical appearance (TT/Tt= tall and tt=short)

Genotype or Phenotype? tall BB Round eyes Gg Brown fur Red hair SS

Homozygous or Heterozygous? Homozygous - carries two identical copies of that gene for a given trait (homo=same) Homozygous dominant = TT Homozygous recessive = tt Heterozygous - carries a different version of the gene (hetero=different) Heterozygous recessive = Tt

Heterozygous or Homozygous? Tt BB qq Gg Rr Ff SS