Bacteria undergo coupled transcription and translation while this process is not possible in single-celled eukaryotes e.g. yeast. Why? 

Because bacterial cells are small and less complex as compared to large eukaryotic cells.

Because bacterial genes are simple and therefore can be simultaneously transcribed and translated as compared to complex genes of eukaryotes.

Because Bacteria contain 70S ribosomes which are capable of translating the mRNA as it is being transcribed instead of 80S eukaryotic ribosomes.

Because Bacteria have their genome and ribosomes in the cytoplasm, while eukaryotes have them separated in the nucleus and cytoplasm.​