Describe and explain how the altered gene could result in flax plants with white-coloured flowers.

Describe and explain how the altered gene could result in flax plants with white-coloured flowers.

• A. The sequence of bases in mRNA would change, leading to different amino acids and enzyme function, so pigment is not produced.
• B. The gene is completely silenced with no transcription.
• C. A pigment-encoding gene duplicates, increasing purple pigment.
• D. A different pigment is produced, resulting in white flowers.

Answer: (A)

The key idea is how a single change in the gene’s code can disrupt pigment production. Flower color in flax often comes from pigments made by a cascade of enzymes. If a mutation alters the mRNA sequence for one of these enzymes, the amino acid sequence of that enzyme can change. That new amino acid can change the enzyme’s shape or active site, usually reducing or abolishing its catalytic activity. If the enzyme can’t perform its step in the pigment biosynthetic pathway, pigment isn’t produced or is produced in too little amounts, and the petals appear white. This direct link between a nucleotide change, a altered protein, and the resulting loss of pigment makes white flowers a likely outcome when the coding sequence is modified. Other scenarios describe different routes to color change, but they don’t illustrate how a single coding-sequence alteration can specifically inactivate pigment production. For example, completely silencing the gene would also stop pigment, but that’s a broader change in gene expression rather than a specific amino acid alteration in the enzyme. A duplication could boost pigment, not remove it, and producing a different pigment could change the color rather than yield white. The described base-change-to-enzyme-inactivation pathway best explains white flowers from an altered gene.

The key idea is how a single change in the gene’s code can disrupt pigment production. Flower color in flax often comes from pigments made by a cascade of enzymes. If a mutation alters the mRNA sequence for one of these enzymes, the amino acid sequence of that enzyme can change. That new amino acid can change the enzyme’s shape or active site, usually reducing or abolishing its catalytic activity. If the enzyme can’t perform its step in the pigment biosynthetic pathway, pigment isn’t produced or is produced in too little amounts, and the petals appear white. This direct link between a nucleotide change, a altered protein, and the resulting loss of pigment makes white flowers a likely outcome when the coding sequence is modified.

Other scenarios describe different routes to color change, but they don’t illustrate how a single coding-sequence alteration can specifically inactivate pigment production. For example, completely silencing the gene would also stop pigment, but that’s a broader change in gene expression rather than a specific amino acid alteration in the enzyme. A duplication could boost pigment, not remove it, and producing a different pigment could change the color rather than yield white. The described base-change-to-enzyme-inactivation pathway best explains white flowers from an altered gene.