Zadanie 7.4 – Matura Dwujęzyczna 2026 – Genetyka

Dział: Genetyka

Treść wprowadzająca

Tetrodotoxin (TTX) is a toxin produced by various animal species. In organisms sensitive to TTX, its molecules bind to sodium channels and thus block the transport of sodium ions through the neuronal membranes. TTX causes muscle paralysis and often death through asphyxiation. Many animal species have developed resistance to the toxin. In populations of organisms insensitive to TTX, mutations in the genes encoding sodium channels have become fixed. TTX-resistant populations were identified among three predatory snake species of the genus Thamnophis. These populations hunt Taricha newts, which produce TTX. In each of the three snake species, substitutions in the amino acid sequence of the sodium channel are present, which are different in each species, but identical within populations of the same species. The phylogenetic tree shown below is based on the analysis of mitochondrial DNA sequences. Black triangles indicate hunting for Taricha newts by the snakes; grey rectangles indicate the snakes’ resistance to TTX.

Polecenie

Explain why a mutation in the gene encoding the membrane sodium channel may result in TTX resistance.

Materiał źródłowy

Zadanie 7.4 – Matura Dwujęzyczna 2026 – Genetyka — ilustracja 1

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