Mitosis and Meiosis

 

Mitosis and Meiosis

Introduction
All new cells come from previously existing cells. New cells are formed by the process of cell division which involves both replication of the cell’s nucleus (karyokinesis) and division of the cytoplasm( cytokinesis).

There are two types of nuclear division: mitosis and meiosis. Mitosis typically results in new somatic (body ) cells. Formation of an adult organism from a fertilized egg, asexual reproduction, regeneration, and maintenance or repair of body parts are accomplished through mitotic cell division. Meiosis results in the formation of either gametes (in animals) or spores ( in plants). These cells have half the chromosome number of the parent cell. You will study meiosis in Exercise 3B. Where does one find cells undergoing meiosis? Plants and animals differ in this respect. In higher plants the process of forming new cells is restricted to special growing regions called meristems. These regions usually occur at the tips of stems or roots. In animals, cell division occurs anywhere new cells are formed or as new cells replace old ones. However, some tissues in both plant and animals rarely divide once the organism is mature.

Exercise 3A.1: Observing Mitosis in Plant and Animal Cells Using Prepared Slides of the Onion Root Tip and Whitefish Blastula

Figure 3.1 Close up view of different stages of mitosis in an onion root tip:

 

 

Figure 3.2 Whitefish Blastula

 

Procedure:
Examine prepared slides of either onion root tips or whitefish blastula. Locate the meristematic region of the onion, or locate the blastula with 10X objective, and then use the 40X objective to study individual cells. Identify one cell which clearly represents each phase of mitosis. Sketch and label the cell in the box provided.

1. The non dividing cell is in a stage called interphase. The nucleus may have one or more dark-stained nucleoli and is filled with a fine network of threads, the chromatin. During interphase, DNA replication occurs.

Interphase

 

2. The first signs of cell division occurs in prophase. There is a thickening of the chromatin threads, which will continue until it is evident that the chromatin has condensed into chromosomes. With somewhat higher magnification you may be able to see the two chromatids held together by the centromere. As prophase continues , the chromatids continue to thicken and shorten. The nuclear envelope disappears and the beginnings of the spindle apparatus begin to appear.

 

Prophase

3. At metaphase, the chromosome pairs have moved to the center of the spindle. One particular part of each chromosome, the centromere, attaches to the spindle. The centromeres of all the chromosomes lie about the same level of the spindle called the metaphase plate.

 

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Metaphase

4. At the beginning of anaphase, the centromere regions of each pair of chromatids separate and are moved by the spindle fibers toward opposite poles of the spindle, dragging the rest of the chromatid behind them. Once each chromatid is separate it is called a chromosome.

 

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Anaphase

5. Telophase, the last stage of division, is marked by a pronounced condensation of the chromosomes, followed by the formation of a new nuclear envelope around each group of chromosomes. The chromosomes gradually uncoil into the fine threads of chromatin, and the nucleoli reappears. Cytokinesis may occur. This is the division of the cytoplasm into two new cells. In plants, a new cell wall is laid down between the daughter cells. In animal cells, the old cells will pinch off in the middle along a cleavage furrow to form two new daughter cells.

 

Telophase

 

Analysis Questions:
1. Why is it more accurate to call mitosis “nuclear replication” rather than “cellular division”?

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2. Explain why the whitefish blastula and onion root tip are selected for study of mitosis.

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Exercise 3A.2: Time for Cell Replication
Procedure:

It is hard to imagine that you can estimate how much time a cell spends in each phase of cell replication from a slide of dead cells. Yet this is precisely what you are going to do in this part of the lab. Since you are working with a prepared slide, you cannot get any information about how long it takes a cell to divide. What you can determine is how many cells are in each phase. From this, you can infer the percent of time each cell spends in each phase.

1. Observe every cell in one high power field of view and determine which phase of the cell cycle it is in. This is best done in pairs. The partner observing the slide calls out the phase of each cell while the other partner records. Then switch so the recorder becomes the observer and visa versa. Count at least two full fields of view. If you have not counted 200 cells, then count a third field of view.

2. Record your data in Table 3.1.

Table 3.1

Number of Cells

Percent of Total Cells CountedTime in Each Stage
Field 1Field 2Field 3Total
Interphase
Prophase
Metaphase
Anaphase
Telophase
Total Cells Counted

3. Calculate the percentage of cells in each phase.

Consider it takes, on average, 24 hours (or 1,440 minutes) for onion root-tip cells to complete the cell cycle. You can calculate the amount of time spent in each phase of the cell cycle from the percent of cells in that stage.

Percent of cells in stage X 1,440 minutes = ___________ minutes of cell cycle spent in stage.

Questions:
1. If your observations had not been restricted to the area of the root tip that is actively dividing, how would your results have been different?

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2. Based on the data in Table 3.1, what can you infer about the relative length of time an onion root-tip cell spends in each stage of cell division?

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Mitosis PPT Questions

Cell Cycle and Mitosis
ppt Questions

Cell Cycle

1.Prokaryotic organisms include ___________, while plants and animals are ____________.

2. Describe prokaryotes.

 

3. How do bacteria asexually reproduce?

4. Name the 3 main steps of binary fission in bacteria.

    a.

    b.

     c.

5. Name a bacterial cell that reproduces by binary fission.

6. Describe eukaryotes.

 

7. How do eukaryotes asexually reproduce cells?

8. The stages in the growth and reproduction of a cell are called the __________ ___________.

9. List the 5 stages in the cell cycle.

 

10. What does G1 stage stand for?

11. Name two things that happen to a cell during G1?

 

12. What is the S stage of the cell cycle?

13. _________ instructions are copied in the S phase as ___________ are duplicated.

14. _______ stands for second growth stage.

15. G2 is the time between ____________ and ___________.

16. Cells continue to _________ during G2 and to make __________ that will be needed for mitosis or cell division.

17. Mitosis or cell division is known as the ________ stage.

18. How does a cell use its energy during the M phase?

19. Does a cell continue growing & making proteins in the M phase?

20. Mitosis is also called _______________ which means division of the ____________.

21. ____________ is called the resting stage and makes up the longest part of a cell’s life cycle.

22. What happens to cells during interphase?

 

23. Are chromosomes visible during interphase?

Mitosis

24. Name the 4 stages of mitosis.

 

25. Name 2 things that happen to a cell during prophase.

     a.

     b.

     c.

     d.

     e.

26. Can chromosomes be seen during prophase?

27. Sketch a eukaryotic chromosome and label the centromere and kinetochore fiber that attaches to it.

 

 

28. How many pairs of chromosomes are found in humans?

29. List 3 things that occur during metaphase.

     a.

     b.

     c.

30. Where are chromosomes located during metaphase of a cell?

31. What stage occurs after metaphase?

32. List 2 things that happen to cells during anaphase.

     a.

     b.

33. Sketch and label the mitotic spindle and attached chromosomes.

 

 

 

 

34. What is the last stage of mitosis?

35. Where are the two sets of chromosomes located at Telophase?

36. What two things reform during Telophase?

37. Chromosomes ___________ during Telophase so they are no longer visible.

38. In plants, what begins to form that will separate the two cells?

39. How are the two cells separated from each other in animals?

 

40. _____________ or division of the cytoplasm follows ___________, division of the nucleus, and forms ____________ daughter cells.

41. How do the two, new daughter cells compare to each other?

 

42. Label the following stages of mitosis.

 

Printable Copy

Metric System

Metric System (SI)
Scientist use a single, standard system of measurement.  The official name of the measurement system is SYSTEME INTERNATIONAL d’UNITES (International System of Measurements) or SI.

The metric system is based on the number 10.

Main Units of Measurement
LengthVolumeMass
meter (m)liter (l)gram (g)

Using the above values (meter, liter, & gram) as the base, their value can be increased or decreased by moving the decimal point to the right (lowers the value) or left (raises the value).

Metric Conversion Table

Kilo-
(k)
Base Unit
(m, l, g)
Centi-
(c)
Milli-
(m)
Micro-
(µ)
nano-
(n)
x 1000meter, gram, liter100100010001000
10001.01.001.000001.000000001

Convert the following values by moving the decimal point the correct number of spaces and in the right direction .

1. 69.8 meters (m) =  ________________ centimeters (cm)

2. 152.97 milliliters (ml)  =  ________________ liters (l)

3. 42.67 liters (l) = _____________ milliliters (ml)

4. 299.32 kilometers (km) = ____________ nanometers (nm)

5. 26 grams (g) = _____________ kilograms (kg)

6. 123.43 centigrams (cg) = ______________ grams (g)

7. 75.2 liters (l)  = __________________milliliters (ml)

8. 456.3 grams (g) = ________________ micrograms µg

9. 4507.22 kilometers (km) = _______________millimeters (mm)

10. 0.00297456 kilograms (kg) = ___________ nanograms (ng)

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Metric Measurement Lab

 

Metric Measurement Lab

 

Part A: Count your drops!

 

Take a guess – How many drops of water will it take to equal 1 milliliter? _____ drops

Follow the directions to find the number of drops in 1 milliliter of water, then answer the questions. You will need a small graduated cylinder (25 ml), a beaker of water, and an eyedropper for this section.  Remember to read the bottom of the meniscus when you are reading the volume of a liquid in a graduated cylinder.

 

  1. Fill a small graduated cylinder with 10 ml of water.
  2. Count the number of drops it takes to raise the water to 11 ml. Record the number in the chart.
  3. Leave the water in the graduated cylinder and count the number of drops it takes to raise the water to 12ml. Record the number in the chart.
  4. Leave the water in the graduated cylinder and count the number of drops it takes to raise the water to 13ml. Record the number in the chart.
  5. Calculate your average and round to the nearest tenth.

 

Picture of graduated cylinder

 

# of drops to 11 ml# of drops to 12 ml# of drops to 13 mlAverage
 

 

 

Based on your average, how close were you to your guess?________

Based on your average, how many drops would it take to make 1 liter? _______

Part B: Water Displacement

 

Follow the directions to find the volume of three marbles using water displacement.

  1. Add 20 ml of water to a 100 ml graduated cylinder. Record this amount in the chart.
  2. Add three marbles to the cylinder and measure the volume. Record this amount in the chart.
  3. Find the difference between the two measurements and record in the chart. The difference between the two measurements will be the volume of the three marbles.
Volume of Water Before adding Marbles (ml)Volume of Water After Adding Marbles (ml)Difference in Volume (ml)Volume of 3 Marbles
 

 

 

Part C: Mass Mania

 

The gram is the standard unit of mass in the metric or SI system. The basic instrument used to measure mass is the mass balance.  Some mass measurements can be made using an electronic balance.

 

 

  1. Check to see that the Pointer is pointing to zero.
  2. If it is not, check to see that all the Riders (weights) are all the way to the left at the Zero mark.
  3. Adjust the balance by turning the Adjustment Screw slowly until it points to zero.
  4. Place your metric ruler on the pan and read & record the ruler’s mass.
  5. After resetting the balance to Zero, measure and record the mass of the empty 50-ml graduated cylinder and then the 3 marbles.
  6. Reset the balance to ZERO when all items have been massed.

 

 

 

Mass of Metric Ruler (g)Mass of Empty 50-ml graduated cylinder (g)Mass of 3 Marbles (g)
 

 

 

Part D: Volume by Formula

 

Use the formula to find the volume of the box. Measure to the nearest centimeter before calculating your answer.  If necessary, Round your answer to Two Decimal places.

 

Volume = length x width x height

__________ x __________ x __________ =________________cm3

 

Part E: Color Challenge

 

1. Obtain the following items from your teacher:

  • 3 beakers with colored water- 25 ml of each color (red, blue, and yellow)
  • 1 graduated cylinder (25 ml – 50 ml)
  • 1 eyedropper
  • 6 test tubes labeled A, B, C, D, E, and F

2. Perform each step outlined below using accurate measurements.

  1. Measure 17 ml of RED water from the beaker and pour into test tube A.
  2. Measure 21 ml of YELLOW water from the beaker and pour into test tube C
  3. Measure 22 ml of BLUE water from the beaker and pour into test tube E.
  4. Measure 5 ml of water from test tube A and pour it into test tube B.
  5. Measure 6 ml of water from test tube C and pour it into test tube D.
  6. Measure 8 ml of water from test tube E and pour it into test tube F.
  7. Measure 5 ml of water from test tube C and pour it into test tube B.
  8. Measure 2 ml of water from test tube A and pour it into test tube F.
  9. Measure 4 ml of water from test tube E and pour it into test tube D.

3. Complete the chart.

Test TubeColorFinal Volume (ml)
A
B
C
D
E
F

Click HERE for Notebook Copy

 

Meiosis Labeling

 

 

Meiosis

 

On each of the images, label the phase of meiosis

1. _______________

2. _______________

3. _______________

4. _______________

5. _______________

6. _______________

7. _______________

8._______________

9._______________

10. _______________

 

11. A cell with a diploid number of 20 undergoes meiosis. This will produce ________ daughter cells, each with ________ chromosomes.

12. Synapsis occurs during this phase: _______________________

13 How many different possible combinations are there for a cell that has 10 chromosomes (5 pairs): _____________

14. Tetrads line up along the equator during this phase: ______________

15. At the end of meiosis I, ________ daughter cells are created. These daughter cells are [ diploid | haploid ].

16. Meiosis occurs in what type of cells: ____________________________

 

Now label the photographs.
17. _______________
18. _______________
19. _____________
20. _______________
21. _______________
22. _____________
23. _______________
24. _______________
24. _____________
25. _______________