Lab #3 - Electron Microscope Sheet & Questions

Lab #3 Electron Microscope Sheet & Questions Micrograph of FIGURE # Measurement in (mm) Magnification Actual Size (mm) Actual Size in “Best Unit” 1 - Chloroplaste LENGTH 225 mm 80 000 2.8125 10 × −3 3 μm 1 - Chloroplaste WIDTH 75 mm 80 000 9.375 10 × −4 938 nm 1 - Average Grana Stack Thickness 13 mm 80 000 1.625 10 × −4 2 nm 1 - Thylakoid Thickness 5 mm 80 000 6.25 10 × −6 6 nm 2 - Mitochondrion LENGTH 160 mm 95 000 1.68 10 × −5 2 μm 2 - Mitochondrion WIDTH 54 mm 95 000 5.68 10 × −4 568 nm 2 - Cristae Thickness 1 mm 95 000 1.05 10 × −5 11 nm 2 - ER Thickness 3 mm 95 000 3.2 10 × −5 32 nm 3 - Nucleus 60 mm 60 000 1.0 10 × −3 1 μm 3 - Nuclear Pore 5 mm 60 000 8.3 10 × −6 83 nm Diagram Labels for Figures 4 and 5: 1. Nucleus 2. Nucleolus 3. Rough Endoplasmic Reticulum 4. Nucleoplasm 5. Smooth Endoplasmic Reticulum 6. Mitochondrion FIGURE 4 IS AN animal CELL 7. Vacuole 8. Chloroplast 9. Cell wall FIGURE 5 IS A plant CELL

QUESTIONS: 1. Would you expect to find more mitochondria in skin cells or muscle cells? Explain briefly. You would expect to find more mitochondria in muscle cells than skin cells. This is because muscle cells are almost constantly in use as us humans are moving in some sort of way pretty much all the time. Our muscles do a lot of work and thus our muscle cells need lots of energy. To create so much energy you need a lot of mitochondria, as they are the “powerhouses” of the cell, and produce energy during the production of ATP. Therefore, since our muscles are constantly being used they need lots of energy, and therefore need lots of mitochondria, more so than skin cells, which is why you’d expect to find more there. 2. Would you expect to find chloroplasts in animal cells? Explain briefly. No, you would not expect to find chloroplasts in animal cells as chloroplasts are used to convert sunlight into food for plants (photosynthesis). Animals don’t need chloroplasts in their cells because they feed themselves through the food that they eat, they don’t produce their own food. Only plants and some bacteria have chloroplasts so that they are able to feed themselves since they don’t get their nutrients the same way animals do. 3. Would you expect to find chloroplasts in all plant cells? Explain briefly. You wouldn’t actually be able to find chloroplasts in all plant cells because not all the cells of a plant are exposed to the sun. Yes, many of them do as they need to produce food for the plant through photosynthesis, but the root cells plants don’t need them because they never see the light of day, and thus will never be able to use their chloroplasts (if they had them) to convert sunlight into food. 4. State one way in which the onion root cell shown in Figure 6 is not a typical plant cell. One way we can tell that the onion root cell shown in Figure 6 is not a typical plant cell is that it doesn’t have chloroplasts. Most plant cells do have chloroplasts, however, since it is a root plant cell it doesn’t need them because it will never need to perform photosynthesis (because it’s underground). 5. Calculate the missing quantities found in the table below. Show your work. Cell Part Actual Size Measurement (mm) Magnification Nucleolus 10 6000 ÷ = 1.67 10 mm × −3 (1.67 10 mm) × −3 × 1000 μm = 1.67 μm ∴ 1.67 μm 10 x 6000