Main Difference – Inheritance vs Polymorphism
Inheritance and polymorphism are two terms used in genetics when describing traits. The main difference between inheritance and polymorphism is that inheritance describes how traits of a particular organism are passed through generations whereas polymorphism describes the different forms of a particular organism that occur within a population. The offspring inherits a set of traits from their parents during sexual reproduction. During the formation of gametes, a single set of chromosomes from parents is transferred to each gamete. Polymorphism arises due to discontinuous genetic variation.
Key Areas Covered
1. What is Inheritance
– Definition, Characteristics, Types
2. What is Polymorphism
– Definition, Characteristics, Role
3. What are the Similarities Between Inheritance and Polymorphism
– Outline of Common Features
4. What is the Difference Between Inheritance and Polymorphism
– Comparison of Key Differences
Key Terms: Alleles, Autosomal Dominant Inheritance, Autosomal Recessive Inheritance, Inheritance, Carriers, Discontinuous genetic variation, Morphs, Polymorphism, Sexual Reproduction
What is Inheritance
Inheritance is the acquisition of traits, which are genetically transmitted from the parents to their offspring. Since humans are diploid organisms, they have two sets of chromosomes in each somatic cell. Each chromosome set is received from each parent. During the formation of gametes, a single set of chromosomes is received by one gamete. In the sexual reproduction, a male gamete is fused with a female gamete to form the zygote. Therefore, the zygote receives one set of chromosomes from each parent. Since the zygote develops into a new organism, it expresses the characteristics of both parents. That means each gene in the genome has two alleles.
The inheritance of traits occurs in three ways: autosomal recessive inheritance, autosomal dominant inheritance, and X-linked inheritance. In autosomal recessive inheritance, the recessive alleles are expressed. In order to be expressed, both alleles should be in the recessive form. The individuals who carry both dominant and the recessive forms are called carriers. Sexual reproduction between two carriers can produce offspring with two recessive alleles in the same individual. In autosomal dominant inheritance, the dominant alleles are expressed. The dominant allele can occur either as homozygous or heterozygous. The inheritance pattern of the genes in the X chromosome is called the X-linked inheritance. Since the number of X chromosomes present in males (XY) and females (XX) is different, differential expressions of the genes can be observed in X chromosomes. The autosomal recessive inheritance is shown in figure 1.
Figure 1: Autosomal Recessive Inheritance
Mutations are also inherited by the offspring in the same way described above. The simplest form of the inheritance was first described by Gregor Mendel.
What is Polymorphism
Polymorphism refers to the occurrence of more than one type of organisms in the same species, which have the same locality. Generally, genetic variation causes the phenotypic variation of organisms of the same species within a population. Different forms of individuals of the same species occur due to discontinuous genetic variation. The discontinuous genetic variations produce two or more sharply-distinct forms within a population. The most obvious example is the development of unisexual organisms in higher organisms. Thereby, a single population can be divided into two as males and females. The different blood types of humans is another example of polymorphism. In the continuous genetic variation, slight variations occur within the population, producing various phenotypes. The variation of the height of individuals in the human population is an example of continuous genetic variation.
Figure 2: Polymorphism in Ducks
When a different form of the individual is produced by a mutation, it is recognized as another ‘morph’ only if the occurrence of that particular individual is too high within the population. Male and female ducks with different morphs are shown in figure 2.
Similarities Between Inheritance and Polymorphism
- Both inheritance and polymorphism are two closely related terms in describing concepts in heredity and genetics.
- Both inheritance and polymorphism are important in increasing the genetic diversity among individuals.
- Both inheritance and polymorphism can be used to describe the behavior of a trait.
Difference Between Inheritance and Polymorphism
Definition
Inheritance: Inheritance refers to the acquisition of traits, which are genetically transmitted from the parents to their offspring.
Polymorphism: Polymorphism refers to the occurrence of more than one type of organisms in the same species, which have the same locality.
Examples
Inheritance: The inheritance of hair color, eye color, as well as several disease conditions are examples of inheritance.
Polymorphism: Male and female sexes and different blood groups in humans are examples of polymorphism.
Correlation
Inheritance: Inheritance can be described in terms of traits or organism level.
Polymorphism: Polymorphism is determined by a particular trait.
Conclusion
Inheritance and polymorphism are two terms that are frequently used in genetics. Inheritance is the passing of different traits in individuals to their offspring. Polymorphism is the occurrence of different forms or morphs within the same species. The main difference between inheritance and polymorphism is the type of concepts described by each term.
Reference:
1. “What is inheritance?” Facts, The Public Engagement team at the Wellcome Genome Campus, 3 Mar. 2017, Available here. Accessed 4 Sept. 2017.
2. “Genetics – Genetic inheritance.” NHS Choices, NHS, Available here. Accessed 4 Sept. 2017.
Image Courtesy:
1. “Autorecessive” By en:User:Cburnett – Own work in Inkscape (CC BY-SA 3.0) via Commons Wikimedia
2. “Anas platyrhynchos male female quadrat” By Richard Bartz using a Canon EF 70-300mm f/4-5.6 IS USM Lens – Own work (CC BY-SA 2.5) via Commons Wikimedia
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