Chapter 5.2 Genetics Since Mendel

1. Chapter 5.2 Genetics Since Mendel

2. When offspring of 2 homozygous plants show an intermediate phenotype • examples: • 1)red flower mated with a white • flower and produces a pink • flower • 2) sickle cell 1. Incomplete dominance

3. 2. Multiple alleles • A trait controlled by more than 2 alleles • traits controlled by multiple alleles will produce more than 3 phenotypes • Examples: blood type • 3 possible blood types A, B, and O • O is recessive to A and B • if you have both an A and B you show expressions of each allele called AB • if you have “A” type you are either AA or AO(same for B, it’s BB or BO) • If you have O blood you can only have OO

4. Occurs when a group of gene pairs act together to produce a trait • example- shades of eye color, hair color, height, skin tone, etc. 3. Polygenic inheritance

5. 4. Environmental Impact • 2 types: • - internal- chemical dominance • - male birds brighter than • females • - external- environment change • - exposure to sun results in • skin cancer • - taking precautions vs. not • - smoking • - alcohol

6. Both parents are heterozygous Xx but both “x” recessive allele holds a disorder. • the child inherits “xx” and has the disorder neither parent knew they carried • example: Cystic Fibrosis 5. Recessive Genetic Disorders

7. 6. Cystic Fibrosis • Recessive genetic disorder • common in Caucasian Americans • can lead to death • occurs when a thick fluid lines the lungs and intestinal tract making it hard to breathe • results in bacterial growth and respiratory infections

8. 7. sex-linked disorders • Occurs in meiosis (sex cell reproduction) • more common in males because males only have one x that needs to be recessive • example: 1. color blindness • On x allele • recessive disorder • 2. Calico cats • - On x chromosome