(a) Study the schematic diagram given below and answer the questions that follow: (i) Identify the polarity from 'X' to ' X̄ ' in the mRNA segment…

• X to X is $\displaystyle 5$’ → $\displaystyle 3$’

• No more amino acids will be added

• as the last codon UAA is a stop codon

• AUG

• Anticodon - UAC

• methionine

• The amino acids are activated in the presence of ATP , and linked to

their cognate tRNA or the adapter molecule,

• Amino acids are activated so peptide bonds can be formed using this

energy.

the RBC in such patients takes up a sickle shape instead of biconcave.

The defect is caused by the substitution of Glutamic acid (Glu) by Valine

(Val) , at the sixth position of the beta globin chain of the haemoglobin molecule /The substitution of amino acid in the globin protein results due to the single base substitution at the sixth codon of the beta globin gene, from

GAG to GUG.

Cross: Carrier (Hb^A Hb^S) x Carrier (Hb^A Hb^S) -> gametes Hb^A, Hb^S from each parent -> offspring $\displaystyle 1$ Hb^A Hb^A (Unaffected) : $\displaystyle 2$ Hb^A Hb^S (Carrier) : $\displaystyle 1$ Hb^S Hb^S (Sickle-cell). It is an autosomal recessive disorder.