Download What structures are common to animal cells

What structures are common to cells?
Introduction
The cell theory states that most living things are composed of units called cells. The
microscope reveals that cells are composed to tiny structures called organelles. Although
plant and animal cells have many of the same organelles, plant cells have certain
organelles that distinguish them fro the cells of animals and animal like protests. All
plant cells have a cell wall and all green plant cells have chloroplasts. Animal cells have
neither a cell wall nor chloroplasts; in other respects, however, the organelles of animal
cells are similar to those of plant cells.
Materials
Lugol’s iodine solution
Toothpicks
Compound microscope
glass slides and cover slips
medicine dropper
onion skin
Procedure:
1. Using the thin membrane from the inside surface of the onion.
2. Prepare a wet mount slide using iodine as the stain.
3. Focus the specimen in low power, draw what you see.
4. Change to high power, focus, draw what you see.
5. Locate the nucleus and cell wall – label in your drawing.
6. Clean your slide.
7. Prepare animal cell slide
8. Place a small drop of iodine solution in the middle of a clean slide. With the flat end
of a toothpick GENTLY scrape the inside of one of you cheeks. This will remove
some of the cells that line the inside or the cheek.
9. Dip the end of the toothpick in the drop of iodine solution on the slide. Twist and stir
the toothpick in the solution in order to detach the scraped tissue from the toothpick.
10. Apply a cover slip and examine the specimen under the low power objective of the
microscope.
11. Draw what you see (using a good area of the specimen)
12. Switch to high power – draw what you see.
Questions:
1. Which organelles can you identify?
2. What is the advantage to staining cells?
2. In what ways do animal cells resemble plant cells?
3. In what ways do animal cells differ from plant cells?
4. What is the function of human cheek lining cells?
5. How are cheek lining cells adapted to their function?
6. Which cell appeared larger, the plant cell or the animal cells?
7. What cell part did you observe around onion cells that you did not see around
cheek cells?
8. Cheek cells often appear folded over, while onion cells don’t. Give one reason
why this is true.
9. Why is it difficult to see the cell membrane in onion cells?
10. The onion cells appear to have two dimensions – length and width. With the
help of your microscope, how can you determine whether it also has thickness?
11. Which organelle usually present in plant cells is absent from the cells of the
onion skin