Question

Differentiate between Linkage and Crossing over.

Answer 1

Hint: Similarities between parents and offspring are dependent on linkages while differences are due to crossing over. Linkage is explained by Hunt Morgan. Crossing over was explained by Harriet Creighton and Barbara McClintock.

Complete Answer:
- Mendel haw given the Law of Independent assortment. According to this law, during gamete formation the two alleles of the same gene segregate independently. This law is not followed in all cases.
- But if the two genes are found on the same chromosome and are very close to each other they cannot segregate independently. Such genes are said to be linked.

Sl.No	Linkage	Crossing over
1.	The tendency of the genes on chromosomes to stay together and thus pass to the next generation is linkage.	This leads to separation of the genes
2.	This is related to individual chromosomes	This is seen between non-sister Chromatids of homologous chromosomes.
3.	The parental traits are maintained in the offspring	The parental traits are changed due to Crossing over
4.	The tendency decreases with age	The tendency increases with age
5.	This is responsible for less variations in the offsprings.	This is responsible for more variations in the offsprings.
6.	Linkage is inversely proportional to distance between the genes	Crossing over is directly proportional to distance between the genes

Note: Linkage reduces the chance of recombinations. It thus helps to maintain the parental characteristics.
Crossing over plays a major role to improve the varieties of plants and animals.