1. 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.

2. 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 

3. 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.

5. 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