What is the Difference Between Monohybrid Cross and Reciprocal Cross

The key difference between monohybrid cross and reciprocal cross is that a monohybrid cross is a single cross between two organisms made to study the inheritance pattern of single pair of genes while a reciprocal cross is two crosses concerning the same character but reversing the roles of males and females to confirm the results obtained from an earlier cross.

Genes are short sections of DNA of chromosomes. Usually, genes exist in pairs within an organism. An individual within a population has two copies (alleles) of a gene. If both copies are the same, the individual is said to be homozygous for that particular trait. On the other hand, if the two copies are different, the individual is said to be heterozygous for the same trait. There are many crosses used to study the inheritance pattern of genes. Monohybrid cross and reciprocal cross are two types of crosses used in genetics to study the inheritance pattern of genes.

CONTENTS

1. Overview and Key Difference
2. What is a Monohybrid Cross
3. What is a Reciprocal Cross
4. Similarities – Monohybrid Cross and Reciprocal Cross
5. Monohybrid Cross vs Reciprocal Cross in Tabular Form
6. Summary – Monohybrid Cross vs Reciprocal Cross

What is a Monohybrid Cross?

A Monohybrid cross is a single cross done between two organisms that differ in a single given trait. This is a basic cross used to study the inheritance pattern of genes in breeding experiments. Normally, the character being studied in a monohybrid cross is governed by two variations for a single locus. To carry out such a type of cross, each parent is chosen to be homozygous (true-breeding) for the given trait. Gregor Mendel theorized the basic rules of inheritance. He used monohybrid crosses extensively for his experiments.

Monohybrid cross determines the dominance relationship between two alleles. The cross starts with the parental generation. Generally, one parent is homozygous for one allele, and the other parent is homozygous for the other allele. The offspring make up the first F1 generation. Moreover, every member of the F1 generation is heterozygous and expresses a dominant phenotypic trait. Crossing two members of the F1 generation produces the F2 generation. According to probability theory, three-quarters of the F2 generation will have the dominant allele’s phenotype while the remaining quarter will have the recessive allele’s phenotype. Furthermore, this predicted 3:1 phenotypic ratio (1:2:1 genotypic ratio) assumes Mendelian inheritance.

What is Reciprocal Cross?

A reciprocal cross is a cross involving two crosses concerning the same character but reversing the roles of males and females to confirm the results obtained from an earlier cross. For example, if pollen (male) from tall plants is transferred to the stigmas (female) of dwarf plants in the first cross, the reciprocal cross would incorporate the pollen of dwarf plants to pollinate the stigmas of tall plants. Therefore, the reciprocal cross is a breeding experiment widely used in genetics to test the role of parental sex on a given inheritance pattern. However, all parent organisms should breed true to carry out such kind of experiment properly.

Furthermore, the reciprocal cross was used in earlier genetic experiments such as research carried out by Thomas Hunt Morgan in sex linkage studies. He used a reciprocal cross to prove white eye in Drosophila melanogaster is sex-linked and recessive. Therefore, reciprocal crosses are used to detect sex linkage and maternal inheritance.

What are the Similarities Between Monohybrid Cross and Reciprocal Cross?

• Monohybrid cross and reciprocal cross are used in genetics to study the inheritance pattern of genes.
• Both crosses are used in Mendelian genetics.
• Both types of crosses were first found by Gregor Mendel.
• All parent organisms should be true breeding to carry out both crosses.
• Both experiments are widely used in classical genetic breeding experiments.

What is the Difference Between Monohybrid Cross and Reciprocal Cross?

A Monohybrid cross is a single cross done between two organisms to study the inheritance pattern of single pair of genes, while a reciprocal cross involves two crosses concerning the same character but reversing the roles of males and females to confirm the results obtained from an earlier cross. Thus, this is the key difference between monohybrid cross and reciprocal cross. Furthermore, a monohybrid cross is used to determine the dominance relationship between two alleles, while a reciprocal cross is used to determine the sex linkage and maternal inheritance.

The below infographic presents the differences between monohybrid cross and reciprocal cross in tabular form for side by side comparison.

Summary – Monohybrid Cross vs Reciprocal Cross

Different types of crosses are used to study the inheritance pattern of genes such as monohybrid, dihybrid, back cross, reciprocal cross, etc. A monohybrid cross is a single cross between two organisms and is made to study the inheritance pattern of single pair of genes, while a reciprocal cross involves two crosses concerning the same character but reversing the roles of males and females to confirm the results obtained from an earlier cross. So, this summarizes the difference between monohybrid cross and reciprocal cross.

Reference:

1. “Monohybrid Cross.” An Overview | ScienceDirect Topics.
2. “Reciprocal Crosses.” An Overview | ScienceDirect Topics.

Image Courtesy:

1. “Monohybrid Punnett Square (AA x Aa)” By RobNobody – Own work (CC0) via Commons Wikimedia
2. “Sex-linked inheritance” By GYassineMrabetTalk✉  This W3C-unspecified vector image was created with Inkscape . – Own work (CC BY-SA 3.0) via Commons Wikimedia