Directions: 1. Read the article below 2. Complete the three comprehension questions on a sheet of lined paper. You will turn in this assignment. Yes, you MUST write in complete sentences. 3. Complete the online mitosis activity
PART I: READING To study mitosis, biologists often look at particular cells. Remember, that mitosis occurs only in areas of growth, so finding a good spot to study it can be challenging. Two specimens are commonly used by biologists to study mitosis: the blastula of a whitefish and the root tip of an onion.
The whitefish embryo is a good place to look at mitosis because these cells are rapidly dividing as the fish embryo is growing. The onion root is also a good place because this is the area where the plant is growing. Remember that when cells divide, each new cell needs an exact copy of the DNA in the parent cell. This is why mitosis is only visible in cells that are dividing, like the whitefish embryo and the onion root tip.
Mitosis can take several hours to complete. Scientists will make slides of cells that should be undergoing mitosis in order to find a particular cell in any of the stages - prophase, metaphase, anaphase, and telophase. Remember that most cells you see will be in interphase, that's the cells "resting" state. Your task is to look at photographs of actual slides and identify the stages of mitosis. Answer the three reading comprehension questions on a sheet of lined paper! Yes, you must write in a complete sentence!
1. Why is the whitefish used to study mitosis?
2. What are the four stages of mitosis?
3. How long does it take for mitosis to complete? Why will most of the cells you view be in interphase?
Part II: Online Activity Go to the website below. Read the introduction, and then click the “next”button. Make sure you read the text on each page BEFORE starting the activity.
In this activity, you will be presented with cells from the tip of an onion root. You will classify each cell based on what phase it is in. At the end you will count up the cells found in each phase and use those numbers to predict how much time a dividing cell spends in each phase. You can base your calculation on a total cell cycle of 24 hours.
Copy the table below on your sheet of lined paper. Enter data in this table while using the website above. You will have 36 cells to classify. When you’re finished, record your data in the chart below. Round to whole numbers.