Bio 103, Lab 3: From Organisms to Cells - Size Relationships

Crystal Reed

Eri Koike

Andy Kim

Hypothesis: We began our experiment with the prediction that there will be little correlation between cell sizes and the size of the organism itself. The reasoning behind such hypothesis was that organisms vary such greatly in size while there is little difference in the size of the cells; we believe that genetic information stored in DNAs play a bigger role.

 

Observations: (Big --> Small)

1. Human cheek sample (10 X) 50-80 microns

2. Jejunum (Pig Intestine) (40 X) 2.6-5.2 microns

3. Coleus (Stem Tip) (4 X) 26-65 microns

4. Pine Stem (4 X) 26-182 microns

5. Euglena (Protist) 20 -50 microns

6. Mixed Flagellates (40 X) 2.6 microns

Conclusion: We found that are hypothesis proved to be correct to a certain extent. The differences in cell sizes were huge, contrary to our prediction. However, little connection seemed to exist between the size of the cells and their parent organism. We found that organism size may have more to do with the complexity of the cells, as observed in both the pig intestine and the pine stem sample.

 

Kaitlin Cough and Elizabeth Harnett

Before we started looking at the different organisms under the microscope, our hypothesis was "providing that the cells are the same size, the bigger the organism the more cells it will have." We believed that the cells would be the same size for the different organisms and there would be a direct relationship between the size of the organism and the number of cells. We observed seven different organisms: a buttercup, shark brain, pine stem, spirogyra, coleus stem tip, jejunum and Elizabeth's cheek cell.

Needless to say we quickly disproved our hypothesis. After looking at our first organism we realized that there were many different cells and were variable in size and color. There was no correlation between the size of the cell and the size of the organism. Below are our measurements for each of the organisms:

Buttercup: had two different types of cells, the outside blue cells (ground cells) were an average of 50 microns and the middle pink cells (vascular cells) ranged from 5.2 to 23.4 microns.

Shark Brain: all relatively the same size, purple in color, 2.6-5.2 microns on average.

Pine Stem: 4 different types of cells, the middle pink cells were 52 microns on average, smaller pink cells that were 10 microns, green outer edge cells were 38.2 microns on average and the small green cells were 7.8 microns on average.

Spirogyra: Small blue cells, 10.4 microns on average.

Coleus Stem Tip: Green cells with purple nuclei, 7.8-20.8 microns.

Jejunum: Pink cells, 2.6 microns

Cheek Cell: Blue cells, 2.6 microns.

After reviewing our observations the plant cells seem to be much larger than the animal cells. The animal cells are all about the same size: 2.6 microns.

 

Kyree Harmon

Kerlyne Jean

We believe that the larger the organism, the larger the cells that compose it. To test this, we collected 5 cell specimen, 3 plants and 2 animals. For each sample, we measured the largest cell and the smallest cell. The first sample was from Coleus. Its smallest cell was 5.2 microns and its largest was 31.2. Next we used Buttercup Root whose smallest cell was about 7.8 microns and largest was about 78. Then we observed the Pine Stem with a range of 13 microns to 52 microns. The first animal specimen was from a pig, whose smallest cells were about 2.6 microns and largest were 5.2. The last specimen that we observed was from Kerlyne's mouth and the cells there ranged from 2.6 to 5.2 microns. Based on our observations, we see somewhat of a correlation in our plant group. For the plant specimens, the larger the plant, the larger the smallest cells were. There was an upward trend for the largest cells, but they were not ordered. For the animal samples, both animals' cells were about the same size. More animals would have to be tested in order to make more accurate summaries concerning the size of the animal cells. However, our plant data seemingly supports our hypothesis. The difference in larger cell size can be attributed to cell growth and development and/or human error. It is still important to note that within each organism, there is a great variety of cell size and many more observations should be made and summarized.

We hypothesized that the size of an organism has no effect on the size of that organism's cell. We saw no reason to conclude that large organisms would have large cells, and suspected that large organisms simply had more cells.

 

Below, we list the largest and smallest cells evident in each organism. Organisms are listed from smalled to largest.

1. Protista: cells were 30 to 40 microns wide, and about 100 microns long.

2. Buttercup root: 20 to 60 microns

3. Coleus: 7 to 15 microns

4. Pig: 3 to 6 microns

5. Pine stem: 10 to 30 microns

 

The general trend we discovered was that smaller organisms possessed larger cells. This is true in every case except the pig, which is also the only animal of our samples and so has different cell structure. It warrants more investigation to discover if this pattern holds true for larger samples of both plant and animal cells. We would guess that in general, smaller plants have larger cells and larger plants have smaller cells.

 

However, it is important to note that there is a great deal of variety in cell size within an organism. This could be seen in various samples, such as the coleus, which had very small cells around the edges and larger cells toward the center of the structure. A better question than if larger organisms have large cells would be whether the role of a cell in an organism affects the size of that cell.

 

Jen Bonczar, Marie Sager

Our initial hypothesis was that bigger organisms have bigger cells.

We observed five different types of cells, from all different sizes of organisms.

The smallest organism whose cells we observed was the buttercup root. The smallest sized cell was 20 microns in diameter, the largest was 50 microns in diameter, and the average was 35 microns in diamater.

The next largest organism was the pine stem. Results for the cells of this organism were approximately the same as the buttercup root, with cells being about 35 microns in diameter.

The Coleus plant, our next largest organism, had many different cell sizes. The sizes of the cells ranged from 25 square microns all the way to 1500 square microns.

Pig cells were approximately 7.2 microns in diameter.

Finally, we scratched some cells from the inside of Marie's cheek and colored them with a blue dye. We observed two specimens, one of which was about 50 microns in diameter with the second being 70 microns in diameter.

Currently, the observations allow us to construct the story that cell size is independent of organism size except for in the case of single cell organsims. This disproves our intial hypothesis. The pig cells we observed were much smaller than those of the buttercup root, yet a pig is much much larger than a buttercup root (pigs eat buttercups for breakfast). Also, organisms had many different sizes of cells, as is demonstrated in our observations of the buttercup root, pine stem, and coleus plant.


We also have a secondary hypothesis that bigger organisms have more cells, but this is an untestable hypothesis as we do not have whole organisms; thus we did not dwell on it in our observations. Still, it seems logical that bigger organisms would have more cells than larger ones simply because a larger organism has more volume of matter.