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प्रश्न
Attempt any TWO of the following:
‘The gene for sickle cell anaemia in homozygous condition is lethal and produces sickle cell trait in heterozygous carrier’. Explain.
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उत्तर
Sickle cell trait describes a condition in which a person has one abnormal allellof the hemoglobin beta gene (is hetrozygous), but does not display the severe symptoms of sickle cell disese that occur in a person who has two copies of that allele (is hemozygous). Those who are heterozygous for the sickle cell allele produce both normal and abnormal hemoglobin (the two alleles are condominant with respect to the actual concentration of hemoglobin in the circulating cells).
Sickle cell disease is a blood disorder wherein there is a single amino acid substitution in the hemoglobin protein of the red blood cells which causes these cells to assume a sickle shape, especially when under low oxygen tension. Sickling and sickle cell disease also confer some resistance to malaria parasitization of red blood cells, so that individuals with sickle-cell trait (heterozygotes) have a selective advantage in environments where malaria is present.
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संबंधित प्रश्न
Why are thalassemia and haemophilia categorized as Mendelian disorders? Write the symptoms of these diseases. Explain their pattern of inheritance in humans.
What is the reason for the 21st trisomy?
Mention the symptoms of Phenylketonuria.
Match Column I with Column II and select the correct option:
| Column I | Column II | ||
| p. | Pleiotropy | I. | More than two alleles occur at the same locus on homologous chromosomes |
| q. | Multiple alleles | II. | Expression of both the alleles m heterozygous condition |
| r. | Polygenic | III. | Multiple effect of single gene |
| s. | Co-dominance | IV. | Single phenotypic character influenced by more than two genes |
Following list indicates various genetic diseases. Identify the diseases that are not caused due to single gene defect.
Huntington's chorea, alkaptonuria, Sickle cell anaemia, Down syndrome, thalassemia, Taysachs disease, Turner syndrome, cystic fibrosis, haemophi Lia, Klinefelter syndrome, albinism
Females with Turner’s syndrome have ______.
Fused ear lobes appear in the progeny due to an autosomal recessive gene. Work out the genotypes of number in the given pedigree.
Short stature in females, webbed neck absence of menstrual cycle and sterility are characteristics which of the following disease?
Why is thalassemia cotegorised as a Mendelian disorder? Write the symptoms and explain the causes of the disease. How does it differ from Sickle cell anaemia?
Describe Klinefelter’s syndrome.
