Consider the Pathway for the Synthesis of the Amino Acid

question 28

Multiple Choice

Consider the pathway for the synthesis of the amino acid arginine in Neurospora: $\begin{array}{ll}&A R G-E&&A R G-F&&A R G-H\\\text { ornithine }& \rightarrow &\text { citrulline } &\rightarrow& \text { argininosuccinate } &\rightarrow&\text { arginine }\end{array}$
Mutant strains of Neurospora may carry one or more mutations.Neurospora mutant strain a is grown on minimal media plus supplements as shown.Growth is shown by (+) and no growth is shown by (o) .Growing strain a cells accumulate citrulline. $~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\text { Supplements }$
$\begin{array}{ccccc}\begin{array}{c}\text { mutant } \\\text { strain }\end{array} & \text { nothing } & \text { ornithine } & \text { citrulline } &\begin{array}{c}\text { arginino-}\\\text { succinate }\end{array}&{ arginine }\\a&0&0&0&0&+\end{array}$ Which statement is true about strain a?

• A)It has one mutation in ARG-H.
• B)It has two mutations, one in ARG-F and one in ARG-H.
• C)It has two mutations, one in ARG-E and one in ARG-H.
• D)It has two mutations, one in ARG-E and one in ARG-F.
• E)It has mutations in ARG-E, ARG-F, and ARG-H.

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Definitions:

Pregnant Women

Refers to females who are in the state of carrying a developing embryo or fetus within the uterus.

Monozygotic Twins

Twins that are genetically identical because they were formed from a single fertilized egg that split into two, sharing 100% of their DNA.

Dizygotic Twins

Also known as fraternal twins, they develop from two separate eggs fertilized by two different sperm cells, resulting in genetically distinctive siblings.

Teratogens

Agents, such as chemicals, viruses, or radiation, that can cause congenital anomalies or developmental malformations in a fetus when exposed during pregnancy.