Identify molecules P and R, describe the function of mRNA in protein synthesis, and explain the impact of a mutation on protein synthesis.

The mRNA codon P is UCA.

In DNA, Adenine (A) pairs with Thymine (T), and Guanine (G) pairs with Cytosine (C). When transcribing from DNA to mRNA, Adenine (A) in DNA pairs with Uracil (U) in mRNA, and Thymine (T) in DNA pairs with Adenine (A) in mRNA.
Given mRNA codon: U C A
Complementary DNA triplet: A G T

The sequence of the DNA base triplet complementary to the codon P (UCA) is AGT.

Question 2.1.3

The nitrogenous base sequence on the mRNA molecule (codons) determines the specific sequence of amino acids that will be joined together to form a protein. This sequence dictates the protein's unique structure and function.

Question 2.1.4

A change in the DNA base triplet (a gene mutation) would lead to a change in the complementary mRNA codon during transcription.

This altered mRNA codon might then code for a different amino acid during translation. A change in the amino acid sequence can alter the protein's primary structure, which can subsequently affect its three-dimensional folding and ultimately its function.

Question 2.1.5

The organelle where proteins are synthesised in a plant cell is the ribosome.