Download Section 6-1

Section 6-1
Human Inheritance
Patterns of Human Inheritance
• Traits controlled by single genes with only two alleles
– Height in pea plants
– Widow’s peak
– Stuff from last unit
• Multiple Alleles
– Some traits controlled by a single gene with more than two alleles
• Blood type – controlled by three alleles
– Type A – IAIA or IAi
– Type B – IBIB or IBi
– Type AB - IAIB
– Type O - ii
• Traits controlled by many genes
– At least four genes are responsible for height in people
– Skin color is controlled by three genes
• Each gene is controlled by two alleles
• Therefore almost endless combinations
Sex Linked Traits
• Male or Female
– XX = Female
– XY = Male
• Sex Linked Genes
– Located on the X and Y chromosomes
– Males more likely to have recessive sex linked
traits