Both budding yeast and the bacteria E. coli are unicellular life. Which of the following statements explains why budding yeast can undergo sexual reproduction while E. coli cannot
(a) Unlike E. coli, budding yeast can alternate between a diploid state and a haploid state.
(b) Unlike E. coli, budding yeast cannot multiply by undergoing cell division.
(c) Unlike E. coli, haploid budding yeast cells can undergo meiosis to produce the gametes necessary for sexual reproduction.
(d) E. coli DNA is unable to undergo homologous recombination, making it incapable of producing gametes.
Choice (a) is correct. The budding yeast can also multiply by undergoing cell division [choice (b)], although the diploid state can either reproduce by cell division or undergo meiosis to produce haploid gametes that can either fuse with another haploid gamete to form a diploid cell, or can become a free-living haploid cell that multiplies by cell division. A budding yeast cell must be diploid to undergo meiosis; haploid cells cannot undergo meiosis [choice (c)]. E. coli can undergo homologous recombination and uses this process for DNA repair [choice (d)]. In fact, E. coli can shuffle their genomes through a process of conjugation, where DNA is transferred from one bacterium to another and may get incorporated in the E. coli genetic material by recombination. Although this conjugation process can lead to the transfer of genetic material, it is not typically considered sexual reproduction.
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