Chapter 4, Problem 1CONQ

Describe the differences among dominance, incomplete dominance, codominance, and overdominance.

Summary Introduction

To review:

The differences between dominance, over dominance, co-dominance, and incomplete dominance.

Introduction:

Genetic inheritance takes place due to the genetic material in the form of DNA or deoxyribonucleic acid which is passed on from the parents to their infants or offspring. Inheritance pattern can be dominant, recessive, co-dominant, orincomplete dominant.

Explanation of Solution

The differences between dominance, co-dominance, overdominance, and incomplete dominance is given in the table below:

Dominance	Overdominance	Codominance	Incomplete dominance
Only dominant allele expresses its phenotype while the recessive ones remain suppressed.	It is the condition in which heterozygous expression of phenotype is superior because of its beneficial effect.	Both the alleles will express their phenotype simultaneously.	It occurs when two alleles produce an intermediate phenotype.
Only one phenotype is expressed because of expression of only the dominant allele.	Expression of alleles in heterozygous condition.	Equal expression of both the allelessimultaneously.	Both the alleles are expressed partially at a time.
Phenotype is similar to one of the parental alleles.	No new phenotype is formed.	It generates a different phenotype from the parental ones.	An intermediate phenotype is generated.
Example: Mendelian traits in pea’s plant(Pisum sativum).	Example: Sickle cell anemia in humans.	Example: ABO blood group characters in human.	Examples: Production of pink coloured flower in Mirabilis jalapa.

Conclusion

Therefore, it can be concluded that dominance means expression of phenotype of only one allele over another allele. Overdominance refers to the expression of phenotype of the heterozygotes which is superior to homozygotes. Incomplete dominance refers to the condition when both the heterozygotes show an intermediate phenotype. In co-dominance, both the alleles in the heterozygote will express their effects independently.