Sickle Cell Anaemia | Thalassemia | ||
I | Mode of inheritance | Autosomal recessive | Sex linked recessive |
II | Cause | Substitution of valine by glutamic acid due to a single base substitution at the sixth codon of the beta globin chain | Mutation or deletion of genes located on chromosomes 11 or 16 |
III | Effect on haemoglobin | Qualitative – incorrectly functioning globin | Quantitative – synthesis of too few haemoglobin molecules |
I. | Down’s syndrome | Trisomy 21; Simian palmar crease, Furrowed tongue, Mental retardation |
II. | Klinefelter’s syndrome | 47,XXY; Genetically female, gynaecomastia and sterility |
III. | Turner’s syndrome | 45, XO; genetically male, Rudimentary ovaries, lack of secondary sexual characters |
1. | more than two genes affecting a single character. |
2. | presence of several alleles of a single gene controlling a single crossover. |
3. | presence of two alleles, each of the two genes controlling a single trait. |
4. | a single gene affecting multiple phenotypic expressions. |
1. | Henking | 2. | Thomas Hunt Morgan |
3. | Sutton and Boveri | 4. | Alfred Sturtevant |
A. | This disorder was first described by Langdon Down (1866). |
B. | Such an individual has overall masculine development. However, the feminine development is also expressed. |
C. | The affected individual is short statured. |
D. | Physical, psychomotor and mental development is retarded. |
E. | Such individuals are sterile. |
1. | A and E only | 2. | A and B only |
3. | C and D only | 4. | B and E only |
1. | Thalassemia | 2. | Down's syndrome |
3. | Turner's syndrome | 4. | Klinefelter's syndrome |
1. | 2. | ||
3. | 4. |
List - I | List - II | ||
(Type of cross) | (Phenotypic ratio) | ||
(A) | Monohybrid cross | (I) | 1:1 |
(B) | Dihybrid cross | (II) | 1:2:1 |
(C) | Incomplete dominance | (III) | 3:1 |
(D) | Test cross | (IV) | 9:3:3:1 |
Options: | (A) | (B) | (C) | (D) |
1. | III | IV | II | I |
2. | II | IV | III | I |
3. | II | III | IV | I |
4. | IV | III | I | II |