What is linkage? Who coined the term. Write the name of insect used for this purpose?
What is linkage? Who coined the term. Write the name of insect used for this purpose?
The term sex linked coined by Thomas Hunt Morgan.the insect Drosophila melanogaster used for this purpose Sex linked inheritance or sex linkage is linked group of genes found alongwith sex controlling genes as present on sex chromosome Sex linked inheritance is the inheritance of certain genes togehter along with sex determining genes beacuse of their presence on sex chromosome. The additional genes presnet on the sex chromosome alongwith sex controlling genes are called sex linked genes. The characters controlled by additional genes present over the sex chromosome are called sex linked characters.The first experiment in sex linked inheritance was performed by Morgan on Drosophila melanogaster. He crossed a pure breeding red-eyed female fruitfly with a white eyed male fly. All the Fl flies irrspective of sex were found to be red-eyed indicating that the trait of red eye is dominant over white eye. On inbreeding, F2 generation flies were found to have red and white eye trait in the ratio of 3 : 1. However, all the female flies were red eyed while 50% of the males were red-eyed and50% of the males were white-eyed.Succssive experiments showed that the genes are located over chromosomes. It made possible to predict the transmission of sex linked disorder in the progeny
Q. What is Haemophilia? Why are haemophilic female extremely
rare?
Answer: Haemophilia is a sex linked recessive disorder. The defect is known as bleeder's disease because the exposed blood of haemophiliasp atient fails to coagulate due to the deficiency of blood clotting factor The two types of haemophilia are termed as Haemophilia A and Haemophilia B. There is one Common example of haemophilia B The defect has been inherited by many royal families of Europe through queen Victoria. The haemophiliac female are extremely rare because in female there is menstural cycle after the attainment of
puberty, there is a premature death of the female. Human female are generally carrier of this disorder and remain normal throughout their life
Q. In Which of the following is the sex linked disease ?
À. Haemophilia
B. Down syndrome
Ç. Sickel Cell Anemia
D. All of these
Answer: Haemophilia
Q. Chromosal type of sex determination in Human in ?
À. XX 99
B. XX XY
Ç. YW FF
D. ZZ+ Yy
Answer: XX XY
Q. which of the following Morgan were experiment on ?
À. Dragon fly
B. Fruit fly
Ç. House fly
D. All of these
Answer: Fruit fly