A cell derived from a yeast, the cell comprising: a plurality of genes capable of being controlled bi-directionally with at least one wavelength of light; the plurality of genes comprising a first gene that is capable of being turned on when exposed to the at least one wavelength of light, and turned off when not exposed to the at least one wavelength of light; and a second gene that is capable of being turned off when exposed to the at least one wavelength of light, and turned on when not exposed to the at least one wavelength of light, wherein the cell includes: a first sequence comprising a nucleotide sequence that encodes a light-activated transcription factor that binds to promoter sequences and initiates transcription under certain wavelengths of light; a second sequence comprising a promoter which can be activated by the light-activated transcription factor encoded by the first sequence, the second sequence further comprising a nucleotide sequence that encodes for a metabolic enzyme; a third sequence comprising a promoter which can be activated by the light-activated transcription factor encoded by the first sequence, and further comprising a nucleotide sequence that encodes for a repressor; and a fourth sequence comprising a promoter which can be repressed by the repressor encoded by the third sequence. a plurality of genes capable of being controlled bi-directionally with at least one wavelength of light; the plurality of genes comprising a first gene that is capable of being turned on when exposed to the at least one wavelength of light, and turned off when not exposed to the at least one wavelength of light; and a second gene that is capable of being turned off when exposed to the at least one wavelength of light, and turned on when not exposed to the at least one wavelength of light, wherein the cell includes: a first sequence comprising a nucleotide sequence that encodes a light-activated transcription factor that binds to promoter sequences and initiates transcription under certain wavelengths of light; a second sequence comprising a promoter which can be activated by the light-activated transcription factor encoded by the first sequence, the second sequence further comprising a nucleotide sequence that encodes for a metabolic enzyme; a third sequence comprising a promoter which can be activated by the light-activated transcription factor encoded by the first sequence, and further comprising a nucleotide sequence that encodes for a repressor; and a fourth sequence comprising a promoter which can be repressed by the repressor encoded by the third sequence. a first sequence comprising a nucleotide sequence that encodes a light-activated transcription factor that binds to promoter sequences and initiates transcription under certain wavelengths of light; a second sequence comprising a promoter which can be activated by the light-activated transcription factor encoded by the first sequence, the second sequence further comprising a nucleotide sequence that encodes for a metabolic enzyme; a third sequence comprising a promoter which can be activated by the light-activated transcription factor encoded by the first sequence, and further comprising a nucleotide sequence that encodes for a repressor; and a fourth sequence comprising a promoter which can be repressed by the repressor encoded by the third sequence. <EOS>