$1.$ You engineer yeast cells that express the M cyclin during S phase by replacing the promoter sequence of the M cyclin gene with that of S cyclin. Keeping in mind that yeast cells have one common Cdk that binds to all cyclins, which of the following outcomes could occur during this experiment? Which could not occur? Give a brief explanation of your answers.

A$.$ There will be both M cyclin$$Cdk and S cyclin$$Cdk complexes in the cell during S phase.

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B$.$ Some substrates that are normally phosphorylated in M phase will now be phosphorylated in S phase.

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C$.$ G$1$ cyclins will be expressed during S phase.

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D$.$ S$-$Cdk targets will be phosphorylated during S phase.