An Inventory of Traits Traits are controlled by factors called genes. For each trait listed in your data table, you get one gene from your mother and one gene from your father. For each trait, there is a dominant form and a recessive form. The dominant gene hides the effect of the recessive gene for the trait. Based on your class data, which form of each trait do you think is the dominant form? Explain your answer.

Dominant and Recessive Traits Earlobes  Detached Attached  Roll tongue  Can roll Can’t roll  Dimples  Dimples No Dimples  Right Handed  Right Left  Freckles  Freckles No Freckles  Naturally Curly Hair  Curly/Wavy Hair Straight Hair  Cleft Chin  Cleft in Chin Non-Cleft Chin  Cross left thumb over right when clasping hands together  Left over right Right over left  Able to see red and green  Normal Vision Colorblind  Straight Hairline  Widow’s Peak Straight Hairline  Mid-Digit Hair (hair on middle part of your finger)  Hair No Hair 

Genes are on Chromosome Pairs Individuals inherit genes from PARENTS Genes are located on CHROMOSOMES Each parent contributes ONE gene for each trait Genes code for TRAITS Humans have 46 chromosomes, 23 from each parent Different forms of the same gene are ALLELES EX: Alleles for the eye color gene: blue, green, brown, hazel, etc.

Alleles Interact to Produce Traits An allele is a different form of a gene Phenotype Physical or observable traits Ex: blue eyes, black hair, etc Phenotype is determined by GENOTYPE Genotype Gene pairs, or gene combo Represented by 2 letters (one for each allele) EX: Bb, TT, rr 2 alleles make a GENOTYPE Dominant Gene Stronger trait, hides recessive trait Represented by A CAPITAL LETTER EX: B, T, R Recessive Gene Weaker trait, sometimes hidden Represented by a lower case letter EX: b, t, r