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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
A child suffering from Thalassemia is born to a normal couple. But the mother is being blamed by the family for delivering a sick baby.
- What is Thalassemia?
- How would you counsel the family not to blame the mother for delivering a child suffering from this disease? Explain.
- List the values your counselling can propagate in the families.
State any two symptoms of Down’s syndrome.
Read the following statements and select the correct option.
i. Genetic disorders are broadly categorised as, Mendelian disorders and chromosomal disorders.
ii. Mendelian disorders are caused due to absence or excess of one or more chromosomes or their abnormal arrangement.
iii. Chromosomal disorders are mainly caused due to alteration or mutation in the gene.
Identify the INCORRECT statement.
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 |
The person with Turner’s syndrome has ______.
If both parents are carriers for thalassaemia, which is an autosomal recessive disorder, what are the chances of pregnancy resulting in an affected child?
Rajesh and Mahesh have defective haemoglobin due to genetic disorders. Rajesh has too few globin molecules while Mahesh has incorrectly functioning globin molecules. Identify the disorder they are suffering from.
| Rajesh | Mahesh | |
| A. | Sickle cell anaemia - an autosome linked recessive trait | Thalassemia - an autosome linked dominant trait |
| B. | Thalassemia - an autosome linked recessive blood disorder | Sickle cell anaemia - an autosome linked recessive trait |
| C. | Sickle cell anemia - an autosome linked recessive trait | Thalassemia - an autosome linked recessive blood disorder |
| D. | Thalassemia - an autosome linked recessive blood disorder | Sickle cell anaemia - an autosome linked dominant trait |
In Down's syndrome, karyotyping has shown that the disorder is associated with trisomy of chromosome number 21 usually due to ______.
Select the correct match.
