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Question
An extra alpha chain can be present in haemoglobin in which of the following disorders?
An extra alpha chain can be present in haemoglobin in which of the following disorders?
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Solution
The correct option is B Thalassemia
Haemoglobin has four protein subunits, two α-globin and two β-globin. The Hbb gene codes the $\beta$-chain. Missense mutation, replacement of A by T at the 17th nucleotide of the Hbb gene changes the codon GAG (glutamic acid) to GTG (which encodes valine). The mutated alllele Hbs encodes the abnormal haemoglobin molecules which stick to one another and cause stiffness and sickle shape of red blood cells. The sickle shaped RBC block and damage the vital organs and tissue. The hemoglobin β gene is located on chromosome 11. Thalassemia are a group of blood disorders which are caused by abnormal synthesis of hemoglobin that result from mutations in the HbB and HbA genes present on chromosome 11 and chromosome 16 respectively. Thus, they are the hereditary disorders and are inherited in an autosomal recessive manner. Mutations in the CFTR gene cause cystic fibrosis. Cystic fibrosis is caused by mutation in CFTR gene, present on long (q) arm of chromosome 7, codes for chloride channels. Alkaptonuria is an inborn metabolic error marked by inability of body to the amino acids phenylalanine and tyrosine. A mutation in the HGD gene, that codes for the enzyme homogentisate 1,2-dioxygenase, isresponsible for this disorder. It is an autosomal recessive disorder. Tay-Sachs disease is caused by mutations in the HEXA gene which codes for part of enzyme beta-hexosaminidase A. This enzyme break down a fatty substance in lysosomes. Correct answer is B.
Haemoglobin has four protein subunits, two α-globin and two β-globin. The Hbb gene codes the $\beta$-chain. Missense mutation, replacement of A by T at the 17th nucleotide of the Hbb gene changes the codon GAG (glutamic acid) to GTG (which encodes valine). The mutated alllele Hbs encodes the abnormal haemoglobin molecules which stick to one another and cause stiffness and sickle shape of red blood cells. The sickle shaped RBC block and damage the vital organs and tissue. The hemoglobin β gene is located on chromosome 11. Thalassemia are a group of blood disorders which are caused by abnormal synthesis of hemoglobin that result from mutations in the HbB and HbA genes present on chromosome 11 and chromosome 16 respectively. Thus, they are the hereditary disorders and are inherited in an autosomal recessive manner. Mutations in the CFTR gene cause cystic fibrosis. Cystic fibrosis is caused by mutation in CFTR gene, present on long (q) arm of chromosome 7, codes for chloride channels. Alkaptonuria is an inborn metabolic error marked by inability of body to the amino acids phenylalanine and tyrosine. A mutation in the HGD gene, that codes for the enzyme homogentisate 1,2-dioxygenase, isresponsible for this disorder. It is an autosomal recessive disorder. Tay-Sachs disease is caused by mutations in the HEXA gene which codes for part of enzyme beta-hexosaminidase A. This enzyme break down a fatty substance in lysosomes. Correct answer is B.
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