Question
(a) Protein synthesis requires the services of all three types of RNAs, namely t-RNA, m-RNA and r-RNA. Explain the role of each of them during the process of protein synthesis in prokaryotes.
or
(b) A homozygous tall pea plant with green seeds is crossed with a homozygous dwarf pea plant with yellow seeds.
i) Write the possible phenotype and genotype of F₁ generation.
ii) State the laws of Mendel that are proved true by the F₁ generation.
iii) Mention the F₂ phenotypic ratio along with their possible phenotypes.
iv) Write the genotypes of the male and female gametes produced by F₁ progeny.
Answer :
(a)
tRNA - Act as adaptor molecule, with amino acid binding site and anticodon loop, brings specific amino acid to the amino acid binding site on the ribosome, initiator t-RNA starts the process of translation.
mRNA - Act as a template for protein synthesis, carries information in the form of codon, It has the initiator codon /start codon /AUG to initiate the process, it has the stop codon/UAA/UAG/UGA for termination of the protein synthesis.
rRNA - rRNA organizes itself into ribosomes, there are two sites in the large subunit in which one site is for binding the incoming t-RNA with the corresponding amino acid second site for peptide bond formation, when the small subunit of rRNA (ribosomes) encounters the mRNA the process of translation begins, ribosome also acts as a catalyst for the formation of peptide bond.
or
(b)
i) Phenotype – Tall plant with Yellow seeds Genotype – TtYy
ii)
• Law of Dominance: Out of two contrasting traits only one trait will appear in F₁ generation and is called dominant trait while the one which remain unexpressed is called recessive trait.
• Law of segregation: In a hybrid union trait simply remain together and segregate at the time of gamete formation.
iii) Phenotypic ratio of F₂ Tall yellow : Tall green : Dwarf yellow : Dwarf green 9 : 3 : 3 : 1 iv) Male gametes of F₁ TY Ty tY ty Female gametes of F₂ TY Ty tY ty
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