Question

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pesg: dna replication & protein synthesis

1. give the purpose of each of the following steps in the process of protein synthesis

a) ribosome moving along a mrna: (1 mark)
b) adenine bonding to thymine: (1 mark)
c) an amino acid bonding to a specific trna: (1 mark)
d) forming of peptide bonds: (1 mark)

Explanation:

a) During protein synthesis, when the ribosome moves along mRNA, it reads the mRNA codons. Each codon specifies a particular amino acid. As the ribosome progresses, it helps in the sequential addition of amino acids to form a polypeptide chain. This movement ensures that the genetic code on mRNA is translated in the correct order.
b) Adenine bonding to thymine is a key part of DNA structure. In DNA replication, this base - pairing (A - T) helps in accurately copying the DNA molecule. The complementary base - pairing ensures that the genetic information is preserved as each strand of the original DNA serves as a template for the new strand.
c) When an amino acid bonds to a specific tRNA, the tRNA acts as an adapter. The tRNA has an anticodon that is complementary to a specific mRNA codon. By carrying the correct amino acid (based on its specificity), it ensures that the right amino acid is brought to the ribosome for incorporation into the growing polypeptide chain during translation.
d) Peptide bonds are formed between amino acids. This bonding is crucial as it links individual amino acids together. Through a series of peptide bond formations, a long chain of amino acids (a polypeptide) is created. This polypeptide then folds into a functional protein.

Answer:

a) To translate mRNA codons into an amino - acid sequence.
b) Ensures accurate DNA replication (complementary base - pairing).
c) Allows tRNA to bring the correct amino acid to the ribosome.
d) Links amino acids to form a polypeptide chain.