Once the ER signal sequence emerges from the ribosome, it is bound by a signal recognition particle (SRP)

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#Id: 8966

#Section 3: Genetics, Cellular and Molecular Biology

Molecular Variation (Rate) - Which is the number of substitutions taking place per nucleotide site per year

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#Id: 2234

#Section 3: Genetics, Cellular and Molecular Biology

Nucleotide changes, particularly those at the third position of the codon, that do not alter the amino acid sequence are called synonymous substitutions.

Nucleotide changes in a gene that alter the amino acid sequence of a protein are referred to as non-synonymous substitutions.

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#Id: 8965

#Section 3: Genetics, Cellular and Molecular Biology

Most protein-encoding genes, the synonymous rate of change is considerably higher than the nonsynonymous rate because synonymous mutations are tolerated by natural selection

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#Id: 8967

#Section 3: Genetics, Cellular and Molecular Biology

Nonsynonymous mutations, on the other hand, alter the amino acid sequence of the protein and in many cases are detrimental to the fitness of the organism, so most of these mutations are eliminated by natural selection.

TLS Online TPP Program

#Id: 2236

#Section 3: Genetics, Cellular and Molecular Biology

Highest rates of substitutions in regions of the gene that have the least effect on function, such as the third position of a codon, flanking regions, and introns.

TLS Online TPP Program

#Id: 2237

#Section 3: Genetics, Cellular and Molecular Biology

Neutral selection (Ka/Ks = 1)

Positive selection (Ka/Ks > 1)

Purifying selection (Ka/Ks < 1)