Final answer:
Bacterial cells have structures such as a plasma membrane, cytoplasm, ribosomes, and DNA, but lack a nucleus, defining them as prokaryotes. Their shapes include cocci, bacilli, spirilla, and vibrios, and they can arrange in patterns like chains or clusters. Bacterial arrangements are observable with microscopy and are essential for identification.
Step-by-step explanation:
The structure of a typical prokaryotic cell, such as a bacterium, can be identified by specific features. These cells lack a nucleus, but instead have a plasma membrane, cytoplasm, ribosomes, and DNA. In the bacterial cells observed under the microscope, common shapes include cocci (spherical), bacilli (rod-shaped), spirilla (spiral), and vibrios (curved rods). Bacterial arrangements can be single, in pairs (diplo-), in chains (strepto-), or in clusters (staphylo-).
To label the image with the bacterial cell structure, you would look for the plasma membrane indicated by a thin line encapsulating the cell, the dense area representing the DNA, tiny dots designating the ribosomes, and the entire cell area filled with cytoplasm. The absence of a nucleus is what allows you to positively identify the cell as a prokaryote.
The arrangements of bacterial cells are often a result of their pattern of division and can provide clues to their identification. These arrangements are particularly visible when observing pre-stained slides using an oil immersion objective lens, where additional structures such as bacterial capsules and acid-fast bacilli can also be identified.