Question

The genetic code is thought to have evolved to maximize genetic stability by minimizing the effect on protein function of most substitution mutations (single-base changes). We will use the 6 Arg codons to test this idea. Consider all of the substitutions that could affect all of the 6 Arg codons. Part A How many total mutations are possible?
Part B How many of these mutations are "silent," in the sense that the mutant codon is changed to another Arg codon


Part C How many of these mutations are conservative, in the sense that an Arg codon is changed to a functionally similar Lys codon?

Answer 1

Explanation:

Part A

Codons are three nucleotide bases encoding coding and amino acid or signal at the beginning or end of protein synthesis. In the genetic code, an amino acid is encoded by 3 nucleotides, while there are just 4 bases.A set of amino acids, 20 in total, build proteins from numerous configurations

∴ for 20 amino acids, and 4 nucleotides a minimum of 3 bases is required $N^{3}$ = $4^{3}$ = 64 possible codon arrangements

Given the degeneracy of the genetic code- the code contains more information that necessary multiple codons encode the same amino acid.

·each DNA base pair can mutate into 3 forms, with 3 base pairs per codon, there are 9 possible substitutions

∴ for arginine, with 6 codons... 6×9= 54

∴ 54 mutations may occur for 6 arginine codons

Part B

The wobble hypothesis states that the first two bases within a codon for an amino acid have an exact pairing with anticodons of tRNA. However, the pairing of the third bases may vary or wobble- thus a tRNA can recognise multiple codons.

5'-GAA-3' can recognise two codons, CUU or UUU as..

• wobbling occurs at the 5' end
• purines pair up with pyrimidines in base pairs

This produces a silent mutation, as it has no effect on the subsequent amino acid.

∴With 6 codons of Arginine, 3×6= 18 silent mutations

Part C

Lysine's codons include AAG and AAA... these an only be alternatively formed from mutations in codons for arginine, AGG and AGA. Here the central nucleotide of the codon, G is replaced or substituted with A.

This form of amino acid replacement for one of similar properties (not generally disruptive to the protein sequence) is known as conservative mutation.

Thus, there are 2 conservative mutations.

Further Explanation:

The nucleic acids are comprised of smaller units called nucleotides and function as storage for the body’s genetic information. These monomers include ribonucleic acid (RNA) or deoxyribonucleic acid (DNA). They differ from other macromolecules since they don’t provide the body with energy. They exist solely to encode and protein synthesis.

Basic makeup: C, H, O, P; they contain phosphate group 5 carbon sugar does nitrogen bases which may contain single to double bond ring.

Codons are three nucleotide bases encoding coding and amino acid or signal at the beginning or end of protein synthesis.

RNA codons determine certain amino acids so the order in which the bases occur within in the codon sequence designates which amino acid is to be made bus with the four RNA nucleotides (Adenine, Cysteine and Uracil) Up to 64 codons (with 3 as stop codons) determine amino acid synthesis. The stop codons ( UAG UGA UAA) terminate amino acid/ protein synthesis while the start codon AUG begins protein synthesis.

Learn more about transcription at brainly.com/question/11339456

Learn more about DNA and RNA brainly.com/question/2416343?source=aid8411316

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