Abstract –For this lab there is no experiment to be done only questions to be answered. In this experiment we will categorize and count the cells to compute the mitotic index of the total root area.
Introduction – The purpose of this experiment is to answer questions associated with the onion root tip photos that are pictured in the lab. The questions for this lab will be drawn from the discussion and review section at the beginning of the mitosis lab. Once that section has been reviewed we may begin to answer the questions.
Hypothesis-There is no hypothesis for this experiment
Procedure-Review discussion about mitosis, examine the six photos of the mitosis of onion root on the worksheet provided. After this is done, record your results to the questions associated with each photo in the lab report.
Results- To gain knowledge about Mitosis in plants. By reading the discussion and review we were able to answer questions in lab manual about mitosis. The mitotic index in question K was determined to be 5.5 and taken from the stem.
Discussion- The results showed that the further away from the root the less the mitotic index is. From this lab we learned about the different stages of mitosis and how to determine them.
We answered questions based on the discussion and the six pictures of onion root tip to answer questions about mitosis. We concluded that the further away from the root, the less mitotic index there will be.
A. What is the purpose of mitosis? The purpose of mitosis is the process by which the body builds tissue to grow and repair itself. Some organisms also reproduce asexually through Mitosis and the purpose of it is to create an identical replica of a cell.
B. Why is the cell cycle important for organisms? Mitosis duplicates the cells chromosomes by removing the original parent chromosomes and replacing them with newly replicated chromosomes in two exact copies of the original cell. Mitosis is responsible for growing, replacing and renewing cells in eukaryotes. In preparation for Mitosis the cell duplicates the DNA and most cell organelles.
C. What role does mitosis play in the growth of an embryo? Mitosis begins with one cell and rapidly divides cells creating tissue and allowing the embryo to grow. Without regulated Mitosis the embryo will not grow.
D. What is one main difference in the mitotic processes between plant and animal cells? One main difference in the mitotic process between plants and animals is in the last stage of telophase. In animals telophase is accomplished by the formation of a cleavage furrow, followed by the pinching off of a new cell. In plants, the dividing membrane is called the cell plate.
E. If the cell that has undergone mitosis originally had the diploid (2n) number of chromosomes, then what number of chromosomes will the nuclei in the two new cells have? It will still have a diploid of 2n because chromosomes duplicate before mitosis so the number will be the same as the parent.
F. Can mitosis ever be used for reproduction?
No because Meiosis is the process by which sperm and eggs are produced and involves two separate nuclear divisions and Mitosis requires a cell to have already formed then it duplicates it.
G. What parts of plants are most impacted by mitosis? The entire plant is affected by mitosis but more specifically the growth of the plant is greatly affected by mitosis.
H. Why might mitosis be easier to study in the tip of the root? It is easier to study in the tip of the root because this is where the growth of the plant happens. Mitotic activity increases towards the root cap; gravity guides the growth of the root.
I. Where else in a plant might you find a large amount of mitotic cell division occurring? In the buds or the cambium
J. How might the mitotic index be applied in agriculture? The mitotic index can be used in agriculture to determine what plants can be planted in what season and what kind of climate they can withstand. The mitotic index evaluates the environmental factors on plants. For example, corn can be produced during a certain season, the mitotic index allows for farmers to determine what season it can be planted it, what season it can be harvested it and how much sun they need.
K. What did you compute to be the mitotic index of the combined six slides (assume there are 54 total cells)?
In comparison to the indexes reflected in Figure 8, from approximately which area of a root was the sample taken? The sample was taken from the stem.
Onion root tip photo questions-
1) What phase is this cell undergoing? Telophase
2) What happens after this phase? Cytokinesis, during cytokinesis, the cell divides the cytoplasm, which is the watery.
1) 1. The two center side-by-side cells are undergoing two different phases of mitosis.
a. What are these phases? Prophase and metaphase
b. What diagnostic features can help you with your decision? In prophase, chromosomes are condensed in the nucleus and appear like a little ball of chromosomes. Metaphase ends with the chromosomes arranging themselves along the equatorial plane of the cell.
1) What phase is this cell undergoing? Anaphase
2) How can you tell? Because you can see the spindle fibers pulling the chromatids apart.
1) This cell has clearly visible chromatids.
a. What’s the next phase this cell will undergo? Anaphase
b. Where will the chromatids go in the coming phase- The chromatids will pull further apart creating two separate and identical chromosomes and will then go into telophase.
1) The cell in the lower center is exhibiting signs of what phase of mitosis? prophase 2) What phase does it appear the cell above is
1) Explain what happens during anaphase.
During anaphase the spindle fibers are shorted and pull the sister chromatids apart. The centromeres break thus creating a two separate identical chromosomes. 2) When the chromatids separate, what is each called? Chromosomes