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Cellular and Molecular Biology

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Gene Mutations: Amino Acid Change

CELLS-YTEN6L

The evolution of multicellularity is thought to have involved a single point mutation following a gene duplication that transformed an enzyme into a mitotic spindle orienting protein. Following this point mutation, the enzyme and the new protein coexist.

Below is a diagram of the amino acid sequences from the extant enzyme (guanylate kinase, GK) and from the extant spindle orienting protein (GK protein-interaction domain, GK$_{PID}$) in several species. The changed amino acid is color coded.

With the help of the table of amino acids and their DNA codons, choose the ONE correct point mutation nucleotide change that could have led to this amazing evolutionary transformation.

Assume the point mutation is the first nucleotide of the codon sequence.

Celeste R. Wirsig-Wiechmann Created for Albert.io. Copyright 2016. All rights reserved.

Amino Acid SLC DNA Codons
Isoleucine I ATT, ATC, ATA
Leucine L CTT, CTC, CTA, CTG, TTA, TTG
Valine V GTT, GTC, GTA, GTG
Phenylalanine F TTT, TTC
Methionine M ATG
Cysteine C TGT, TGC
Alanine A GCT, GCC, GCA, GCG
Glycine G GGT, GGC, GGA, GGG
Proline P CCT, CCC, CCA, CCG
Threonine T ACT, ACC, ACA, ACG
Serine S TCT, TCC, TCA, TCG, AGT, AGC
Tyrosine Y TAT, TAC
Tryptophan W TGG
Glutamine Q CAA, CAG
Asparagine N AAT, AAC
Histidine H CAT, CAC
Glutamic acid E GAA, GAG
Aspartic acid D GAT, GAC
Lysine K AAA, AAG
Arginine R CGT, CGC, CGA, CGG, AGA, AGG
Stop codons STOP TAA, TAG, TGA
A

Cytosine to thymine.

B

Serine to proline.

C

Thymine to cytosine.

D

Threonine to tyrosine.

E

Guanosine to adenine.