Question

Support your conclusion with evidence based on the size of the structures you want to see and the resolution and magnification power of different types of microscopes.
What will be an ideal response?

Answer 1

Answer: Transmission electron microscopy would be necessary to visualize the internal structures of a chloroplast. Chloroplasts are less than 5 μm in diameter and the internal membranes are only 10 nm thick. Light microscopes only have a resolution of 200 nm, thus any structure less than 200 nm will not be visible. Individual chloroplasts could be seen with a light microscope, but not the structures inside. Scanning electron microscopy can only see external features because electrons cannot penetrate the cell, thus the cell must be sectioned and prepared for transmission electron microscopy to see the inside of the chloroplasts.

Answer 2

Answer: Mechanisms will vary depending on the organism described, some of which include the involvement of proteins in the cytoplasmic membrane, slime extrusion, and type IV pili. Examples of advantages could include biofilm formation on a surface, increased pathogenesis or movement towards a different habitat with new resources.

Answer 3

Answer: The function of an endospore is to allow the cell to survive harsh conditions by going into a dormant state. An environmental trigger, such as nutrient depletion or dehydration triggers the formation of compounds such as SASP and dipicolinic acid to protect the DNA from damage and reduce the water content inside the endospore. These changes protect the DNA and other critical chemical components from heat, dessication, and UV exposure. The function of an endospore is not for reproduction because every cell forms only one endospore. (The amount of detail expected in this answer should be commensurate with the amount of detail discussed in class.)

Answer 4

Answer: The flagellar apparatus is put together in a particular order first the MS ring, anchoring proteins, and the hook extend off of the cytoplasmic membrane. Flagellin proteins then pass through the narrow filament channel and cap proteins finally are put onto the end when roughly 20,000 flagellin have been assembled. Flagellar growth thus occurs after the assembly of the basal body, rings, and hook. The basal body provides the rotation and uses the proton motive force to rotate the basal body. From the information given above, one can infer that the basal body and hook can still rotate, but the flagellin proteins are missing or defective so that no long flagella can form. This would explain why the cells might still rotate in place, but not be able to move forward rapidly.

Answer 5

Answer: The fatty acid components of the lipids in the cytoplasmic membrane are oriented toward each other, whereas the glycerol-phosphates point out toward the cytoplasm and external environment. Proteins can span the entire membrane (both layers) or be embedded in the phospholipids on either side of the membrane.