Explain the structure of t-RNA with the help of a diagram. Describe its role in the process of translation.

OR

A pea plant producing yellow coloured and round seeds is given with unknown genotypes. Explain how you would find the correct genotypes of the plants with respect to the two traits mentioned. Work out the cross and name it.

tRNA is a single stranded structure of nucleotides. Each tRNA molecule has a triplet of bases which is known as anticodon.

The role of tRNA in the translation process is:

i. Formation of proteins requires the twenty different types of amino acids dissolved in the cytoplasm to be brought to the ribosomes. This is the role of tRNA.

ii. Each tRNA molecule attaches to only one specific type of amino acid.

iii. As the translation process begins the ribosome attaches to the starting end of the mRNA strand. tRNA molecules then each carry a specific amino acid and approach the ribosome.

iv. The tRNA anticodon pairs with the first mRNA codon and the two molecules join together temporarily.

v. Generally, the first codon of mRNA is AUG which is a start codon which starts protein synthesis.

vi. Then another new codon appears which codes a specific protein. This continues until a stop codon like UGA is synthesized.

Therefore, tRNA serves as an adaptor molecule to translate the mRNA messages accurately and helps in protein synthesis.

OR

The correct genotypes of the plants with respect to the two traits mentioned can be found by performing test crosses.

Case 1:

If all phenotypes is yellow and round then the genotype of parents is YYRR. (Homozygous).

Case 2:

Phenotypes : 1 Yellow round and 1 Green round Then the genotype of the parent is YyRR (Heterozygous for yellowness).

Case 3:

Phenotype : 1 Yellow round and 1 Yellow wrinkled. Then the genotype of parent is YYRr (Heterozygous for shape of seed)

Case 4:

Phenotype : 1 Yellow round and 1 Yellow wrinkled and 1 Green round and 1 Green wrinkled. Then parent is YyRr