OBJECTIVE LIFE SCIENCE
MOLECULAR BIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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TAC CAC GTG GAC TGA GGA CAC CTC TTC AGA CGG CAA TGA
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UAC CAC GUC GAC UGA GGA CUC CUC UUC AGA CGG CAA UGA
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UAC CAC GUG GAC UGA GGA CAC CUC UUC AGA CGG CAA UGA
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TAC CAC GTC GAC TGA GGA CTC CUC TTC AGA CGG CAA TGA
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Detailed explanation-1: -Normal hemoglobin contains the amino acid glutamate at position 6 in the primary sequence. In individuals with sickle-cell disease, this glutamate is replaced with the amino acid valine.
Detailed explanation-2: -Genetic studies have shown that the base sequence in normal hemoglobin (HbA) and sickle cell hemoglobin (HbS) differs at only one position (a change from an A to a T). This change to one codon results in a single amino acid change in the hemoglobin.
Detailed explanation-3: -Sickle cell anaemia gets its name from the abnormal shape of the erythrocytes, which resemble that of an old farming tool, the sickle (Figure 13). This shape is due to a single nucleotide substitution (A to T) that converts a glutamic acid codon (GAG) into a valine codon (GUG) in the beta chains of Hb.