Question

1) Why is codon bias important?

2) If you had a bacterial cell in a solution of sodium at 0.5 M outside the cell and 0.8 M inside the cell and K+ at 0.3 M outside the cell and 0.5 M inside the cell. If this is an antiporter, with the sodium coming into the cell as the as potassium (K+) moves out of the cell, which molecule sodium or potassium provides the energy for this transporter? How do you know?

Answer 1

1) Bias in codon refers to synonymous substitution mostly in the third place of the triplet codon. The first two letters in the triplet codon are similar whereas is differs in the third place, this property is attributed as degeneracy and helps in correct substitution of the intended amino acid in the polypeptide chain. The bias in the codon is particularly helpful in case of silent mutation taking place at the third base of the codon and still, no profound effect is formed during correct amino acid assembly.

2) In this case. the potassium molecule (k+) is providing the energy for this transporter to work. At the expense of potassium from inside of the cell to the outside (flowing from higher concentration to lower concentration), it drives the antiporter. Sodium cannot provide the energy because it is moving against the concentration gradient and needs active transport at the expense of energy by the cell.