A)A Met⁺ Strain of Neurospora Was Treated with a Mutagen

question 33

Essay

a)A met⁺ strain of Neurospora was treated with a mutagen to create met^- mutants.The mutants were reverted to met⁺ with HA (hydroxylamine),which causes GC to AT transitions.What was the original mutation on the molecular level?
b)Two of the revertants showed odd results when crossed with a wild-type met⁺ strain.
$$\begin{array} { l l } \text { Cross } & \text { Progeny } \\\text { met } ^ { + } \text {revertant A } \times m et ^ { + } \text {wild type } & 8 8 \% \text { met }^+ \\& 12 \% \text { met }^-\end{array}$$ $\begin{array}{ll}\text { met }^{+} \text {revertant B } \times \text { met }^{+} \text {wild type }& 93 \% \text { met }^{+}\\&7\% \text { met }^-\end{array}$
Explain how these results occurred and why the above numbers of offspring were obtained.

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Definitions:

Psychosexual Development

Sigmund Freud's theory describing how personality develops through stages focused on sexual pleasure from different body areas.

Fixated

In psychology, an obsessive focus or attachment to an idea, person, or object, often at the expense of more useful or adaptive behaviors.

Sexual Abuse

An undesired sexual act by one person upon another, often using coercion or without the consent of the victim.

Sexual Fantasies

Imagined sexual thoughts or desires that can enhance or precede sexual arousal, often incorporating scenarios or behaviors not experienced in reality.