1. Complex Patterns of Inheritance

2. Many patterns of inheritance are not as simple
as Mendel proposed.
Many traits result from alleles with a range of dominance,
rather than strict dominance and recessive relationship.
Some traits are a result of the interaction of several genes.

3. X INCOMPLETE DOMINANCE occurs when two homozygous parents produces
a heterozygous offspring that is
somewhere between the two parents.
---- has a blending affect.
red
white
pink X

4. X RR x WW RW INCOMPLETE DOMINANCE ---- blending affect.
What are the alleles?
Red flower - R
White flower - W
red
white
pink X RR x WW RW
Genotype?

5. Examples of Incomplete dominance

6. X CODOMINANCE occurs when both alleles from
the parents are equally and separately expressed.
Copilot…..Cooperate
homozygous
white flower
homozygous
red flower
red & white
flower X
Both the red and white alleles are separately visible.

7. X RR x WW RW CODOMINANCE - - - both alleles are visible
What are the alleles?
Red flower - R
White flower - W
red & white
flower
white flower
red flower X
Genotype? RR x WW RW

8. Examples of Codominance

9. IA IB IA & IB i Example of Codominance - - - Blood types
Blood Type A and Type B are equally dominant.
Type O is recessive.
Alleles: IA IB
IA & IB i

10. Many genes may interact to produce one trait.
Many genes may interact to produce one trait.
Polygenic traits are traits produced by
two or more genes.
Examples of polygenic traits in humans include:
skin color (three genes)
eye color (three genes)
hair color (five genes)
height (several).

11. also depends on nutrition The environment interacts with genotype.
An individual’s phenotype is more than
the sum of their genes.
An individual’s phenotype often depends
on conditions in the environment.
Arctic Fox
Height in humans
winter coat
also
depends on
nutrition
summer coat

12. Incomplete or Codominance

13. Incomplete or Codominance

14. Incomplete or Codominance

15. Incomplete or Codominance

16. Incomplete or Codominance

17. Incomplete or Codominance

18. Incomplete or Codominance

19. Incomplete or Codominance

20. Incomplete or Codominance

21. Sex-linked Inheritance
A sex-linked gene in a gene
located in a sex chromosome.
Genes on the Y-chromosome are found only in
males and are passed directly from father to son.
Genes located on the X-chromosome are
found in both males and females.