During sexual reproduction, chromosomes are passed on to the offspring. The chromosomes are either passed as it is, or they undergo recombination. The chromosomes that are identical to the parents are called the parental chromosomes. And the chromosomes that recombine are called recombinant chromosomes.
Parental Type Chromosomes
Parental chromosomes are the chromosomes found in an offspring that are similar to their parents’. They show the same phenotype as their parents.
During meiosis, homologous chromosomes (similar chromosomes from both the parents) join together at a point called chiasmata. The chiasmata is the site of recombination for the homologous chromosomes. The event of recombination takes place during meiosis at the time of gamete formation. The non-sister chromatids that do not cross over, form the parental type chromosomes.
Recombinant Type Chromosomes
The homologous chromosomes that are joined to each other at the point of chiasmata undergo recombination. There is an exchange of genetic material between the chromatids which forms a cross-like structure, hence called crossing over.
This exchange brings about genetic variations in the offspring. The extent of crossing over depends upon the distance between the genes present on the same chromosome. If the two alleles are located far apart, the probability of crossing over is much higher. However, when the alleles are situated close to each other, the probability of crossing over decreases.
The recombinant chromosomes produced by crossing over bring about variation in the genotype. It cannot be considered as a mutation because it is a mere exchange of position between the alleles.
Parental vs Recombinant Type Chromosomes
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The chromosomes that are similar to their parents are referred to as parental chromosomes. |
The chromosomes that are different from their parents are referred to as recombinant chromosomes. |
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There is no genetic variation in the offspring. |
There is genetic variation in the offspring. |
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The allelic combination is the same as that of the parents. |
The allele combination is different as compared to the parents. |
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Their phenotype (physical appearance) is similar to their parents. |
Their phenotype is different. |
Explore BYJU’S Biology for more information.
Also Visit:
- What Are the Types of Recombination?
- Homologous Recombination in Eukaryotes
- What Is the Difference Between Recombination and Mutation?
- What are the methods of genetic recombination in prokaryotes?
Frequently Asked Questions
How can you tell if an offspring is recombinant?
Recombinants can be identified by analysing the offspring of the F2 generation. For example, a parent with long pink flowers is crossed with a parent having small white flowers, the number of offspring produced is 100, out of which 10 have long white flowers, 8 have small pink flowers, 40 have long pink flowers and 42 have small white flowers. The percentage of recombinant type of chromosomes is 10+8 = 18%.
A percentage of 50% in the recombinant population shows independent assortment, but since the recombination percentage here is much lower than 50%, it shows the event of crossover recombination.
Which are the three methods of genetic recombination in bacteria?
Conjugation, transformation and transduction are the three methods of genetic recombination in bacteria.
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