Continuing Genetics DOMINANCE Unit 5: Mendelian Genetics

1
Continuing GeneticsDOMINANCEUnit 5 Mendelian
Genetics
2
Independent Assortment

• genes that are inherited separately do not
  influence the inheritance of others
• Alleles segregate independently during meiosis
• some go to one gamete and some to another

3
Types of Dominance

• Incomplete Dominance
• Offspring genotype is heterozygous (hybrid)
• Phenotype is between two parents
• In offspring, Dominant gene cannot fully inhibit
  the recessive
• Ex white flower x red flower pink flowers

4

• Codominance
• Offspring shows phenotype of neither parent
• Both alleles are dominant
• Ex black cow x white cow checkered/spotted cow

Bay horse x white horse roan horse
5

• Multiple alleles more than two alleles control a
  trait
• Ex height, hair color, eye color and blood type

6
Blood type inheritance

• Blood type is determined by the presence or
  absence of proteins on surface of red blood cells
• Blood types A, B, AB and O

Phenotype (BLOOD TYPE)   GENOTYPE   ANTIGEN on red blood cell SAFE TRANSFUSIONS SAFE TRANSFUSIONS
Phenotype (BLOOD TYPE)   GENOTYPE   ANTIGEN on red blood cell TO FROM
A  AA or AO  A  A, AB A, O
B BB or BO  B   B, AB B, O
AB Only AB  A B   AB A, B, AB, O
O  Only OO None   A, B, AB, O O
7
Sex-linked alleles

• controlled by genes located on sex chromosomes
• Usually carried on X chromosome
• Since females are XX, they are usually carriers
  of the trait
• Since males are XY, they have a higher tendency
  for inheritance of trait

8
Sex-linked

• If trait is X-linked males pass it to all of
  their daughters, none to sons
• If trait is X-linked mothers have 50/50 chance
  of passing it to all of their children
• Ex colorblindness, hemophilia

9

• Work the following Punnett Square
• Male has Hemophilia (XhY)
• Female Carrier (XHXh)