There are several types of inheritance including dominant-recessive, incomplete dominance, co-dominance, sex-limited, sex-linked, and polygenic inheritance. Dominant-recessive inheritance involves a dominant trait being expressed when one allele is dominant. Incomplete dominance results in an intermediate phenotype when neither allele is dominant. Co-dominance occurs when both alleles are expressed equally in a heterozygote. Sex-limited and sex-linked traits are dependent on sex chromosomes. Polygenic inheritance involves multiple genes contributing to a single trait and results in continuous variation in phenotypes.

1. Types of Inheritance
CJ Baek
B block IB Biology

2. What is inheritance?
• Genetic trait or characteristic that is
passed on from a parent to the next
generation of offspring

3. Types of inheritance
• Dominant-Recessive
• Incomplete dominance
• Co-dominant
• Sex-limited
• Sex-linked

4. Dominant-recessive
• If both or one of the gametes are dominant,
the dominant trait is inherited by the
offspring
• When one or both alleles is dominant the
organism has the dominant trait
• When it is a homozygous with recessive
alleles, it has the recessive trait

5. Incomplete dominance
• When neither allele has dominance over
the other allele
• The offspring would result as an
intermediate of the two homozygous
parental phenotype, and would therefore
be a heterozygous
• Ex. a pink flower would result when red
and white flowers breed.

6. Co-dominant
• When both alleles in a heterozygous
organism contribute to phenotype
• Both alleles are independently and equally
expressed
• Ex. When a red bull and a white cow
breed a roan colored cow would result

7. Sex-limited
• Cannot be identified with phenotype
• Some characteristics unique to the sex will
not be passed on, such as milking
characteristic of females not being passed
on to male

8. Sex-linked
• Highly dependent on the X chromosome
• X chromosome acts a recessive allele
• XX makes female, XY makes male

9. Polygenetic inheritance
• Single characteristic controlled by multiple
genes

10. Polygenic inheritance in skin color
• Gives rise to continuous variation in
phenotype
• Polygenic alleles can be contributing or
non-contributing
• The genotype varies due to segregation of
alleles and unlinked chromosomes
orienting randomly, and random
fertilization of gametes
• In total 9 genotypes are possible

11. Thank you
• Citation:
http://bowlingsite.mcf.com/genetics/BasGe
n4.html