Virtual Mitosis Lab

Clayton State University

Torsten Wittman

CLICK Here to Begin

This lab is designed for you to use the links to click from one slide to the next. To maximize your learning of this material, use the links to navigate rather than scrolling from one slide to the next. All clickable links appear like this: Clickable Link. You may also see some of the following clickable icons:

Will allow you to view additional microscopic images

Will show you the questions you will need to answer on your lab report

Sawyer 2014

Cell Cycle Review

MITOSIS

G2

S G1

G0

P M

A

T

Let’s begin by reviewing the cell cycle.

The cell cycle includes all of the mitotic phases (including cytokinesis) plus the intervening interphase. The interphase portion of the cell cycle can be further broken down into G1, S, and G2 phases. Non-dividing cells are held within the G0 phase.

Vocabulary Review: Interphase – Growth phase of the cell Mitosis – Division of the chromosomes

in the nucleus Cytokinesis – Division of the cytoplasm and

organelles

CLICK Here to Continue

Interphase

MITOSIS

G2

S G1

G0

P M

A

T

Let’s investigate the phases of Interphase.

Click on each link below to learn about the different phases of Interphase. When you are finished, click the link at the bottom to continue to Mitosis.

CLICK Here to Continue to Mitosis

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G1 Phase

S Phase

G2 Phase

G0 Phase

Appearance of cells in Interphase

Mitosis Go Back

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Click on each link below to learn about the different stages of Mitosis. When you are finished, click the link at the bottom to continue.

Let’s investigate the stages of Mitosis.

Prophase

Metaphase

Anaphase

Telophase

Mitosis Review

CLICK Here to Continue with Cytokinesis

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Use the figure on the right to review the stages of mitosis. Identify each stage and briefly explain what is happening in each stage. Use the “Answers” link to check your answers.

Once you feel comfortable with mitosis, use the link below to continue learning about cytokinesis.

Answers

Cytokinesis Go Back

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Cytokinesis is the physical separation of one cell into two cells. The cytoplasm and all of the enclosed organelles must be divided equally between the two daughter cells.

Because plant cells have cell walls and animals cells do not have cell walls, the process of cytokinesis is different in plant cells and animal cells. Use the links to learn how cytokinesis occurs in each of these cell types.

Cytokinesis in Plant Cells

Cytokinesis in Animal Cells

G1 Phase

Go Back to Interphase Overview

G1

G0

During the G1 phase, the cell is growing and conducting normal cellular functions. The growth of the cell during this phase includes the production of new organelles, an increase in the volume of cytoplasm, and the division of mitochondria and chloroplasts.

S Phase

Go Back to Interphase Overview

S

Sister Chromatids

Once a cell gets a signal to divide, it enters the S Phase. In the S Phase, the cells duplicates its DNA by making copies of each of its chromosomes. Once the chromosomes have been successfully copied, the two copies remain together as a single chromosome made up of two sister chromatids.

G2 Phase

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G2

After the S Phase is complete, the cell moves into the G2 Phase. During the G2 phase, the cell undergoes the final growth needed in preparation for division.

G0 Phase

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G1

G0

Non-dividing cells (like neurons) are said to remain in a G0 phase, which is similar to an extended G1 phase where a cell is conducting normal cellular function and is neither dividing nor preparing to divide.

Prophase

Go Back to Mitosis Overview

Prophase is the first stage of mitosis. Note that your textbook may divide the events that occur during this period of mitosis into “Prophase” and “Prometaphase”. For the purposes of this lab, we will combine events from both of these sub-stages into one phase called “Prophase”.

Key events occurring during Prophase: • Chromosomes condense and become visible • Mitotic spindle begins to form • Nuclear membrane disassembles • Spindle fibers begin to attach to sister chromatids

at the centromere region

Click to view Microscopic Images of Cells in Prophase

Metaphase

Go Back to Mitosis Overview

Metaphase is the second stage of mitosis.

Key events occurring during Metaphase: • Spindle fibers pull sister chromatids to the middle

of the cell • Sister chromatids are lined up along the middle of

the cell Click to view Microscopic Images of Cells in Metaphase

Anaphase

Go Back to Mitosis Overview

Anaphase is the third stage of mitosis.

Key events occurring during Anaphase: • Spindle fibers shorten, pulling sister chromatids

apart • Each complete set of chromosomes moves to the

opposite ends of the cell Click to view Microscopic Images of Cells in Anaphase

Telophase

Go Back to Mitosis Overview

Telophase is the last stage of mitosis. Keep in mind that telophase often occurs at the same time that cytokinesis begins. Telophase itself includes only the events happening in the nucleus of the cell.

Key events occurring during Telophase: • Chromosomes are at opposite poles • Spindle fibers disassemble (break apart) • Nuclear membranes re-form, forming two distinct

nuclei

Click to view Microscopic Images of Cells in Telophase

Cytokinesis in Plants

Go Back to Cytokinesis Overview

In plant cells, the cell cannot pinch in half due to the rigidity of the cell wall. Instead, the cell uses tiny membranous sacs called vesicles to deposit plasma membrane and cell wall material along the middle of the cell between the two nuclei formed in telophase. This area where the vesicles fuse with each other is called the cell plate, and it represents the area where new cell membrane and cell wall is being built. Once the cell plate has expanded sufficiently, the original cell is now divided equally into two independent daughter cells.

Cytokinesis in Animals

Go Back to Cytokinesis Overview

In animal cells, the lack of a cell wall makes cytokinesis a bit easier. Deposits of protein filaments between the two cells forms a contractile ring. Protein interactions causes this region to constrict the cell membrane until the original cell is pinched in two, similar to the mechanism of a drawstring. The result is two independent daughter cells.

Appearance of Cells in Interphase

Go Back to Interphase Overview

Look for: - Intact, solid nucleus - Individual chromosomes are not

easily seen

Cells in Prophase

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Look for: - Appearance of individual

condensed chromosomes with no order

- The nucleus may or may not be clearly defined (the nucleus is easy to see in early prophase, but not in late prophase)

Cells in Metaphase

Go Back to Metaphase

Look for: - Chromosomes lined up in the

middle of the cell

Cells in Anaphase

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Look for: - Chromosomes being pulled apart,

to opposite ends of the cell

Cells in Telophase

Go Back to Telophase

Look for: - Two distinct areas of chromosomes on opposite ends

of cell (individual chromosomes are less distinct) - Early signs of cytokinesis

Plant Cells in Cytokinesis

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Animal Cells in Cytokinesis

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More Cells in Interphase Go Back

More Cells in Prophase Go Back

More Cells in Metaphase Go Back

More Cells in Anaphase Go Back

More Cells in Telophase Go Back

Interphase Questions

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Exercise 1

1.1 Name three things that occur during interphase, and indicate which phase(s) of interphase each is occurring in.

1.2 How can you visually determine whether a cell is in interphase? (From a picture, for example)

1.3 Critical Thinking: Some cells in your body frequently divide, while others in your body rarely, if ever, divide.

a. Think of a type of cell that would frequently divide b. Think of a type of cell that would rarely, if ever, divide c. How would these two cells differ in their interphase? Write your answers in your lab report.

Mitosis Questions Go Back to Lesson

Exercise 2

2.1 a. How many cells are there at the beginning of mitosis? b. At the end of mitosis? c. How alike or how different are the daughter cells from each other?

2.2 Identify in which stage of mitosis each of the following events occurs: a. Nuclear membrane disassembles b. Nuclear membrane reassembles c. Sister chromatids are pulled apart d. Chromosomes condense and become visible e. Sister chromatids line up along the center of the cell f. Spindle fibers begin to attach to sister chromatids

2.3 Critical Thinking: Why do you think that the chromosomes condense before mitosis? (Write your answers in your lab report)

Mitosis Identification Go Back

Exercise 3

Examine the pictures and identify the stage of mitosis (prophase, metaphase, anaphase, telophase) for each picture. Write you answers on your lab report.

1. 2.

Next

Mitosis Identification, Page 2

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Exercise 3

3. 4.

Next

Mitosis Identification, Page 3

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Exercise 3

5. 6.

Next

Mitosis Identification, Page 4

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Exercise 3

7. 8.

Go Back to Lesson

Cytokinesis Questions Go Back to Lesson

4.1 Why does cytokinesis differ in plant cells and animal cells?

Exercise 4

4.2 Fill in the Blank: In plant cells, vesicles carrying material to build a cell wall fuse along the __________________ between the two daughter cells.

4.3 Fill in the Blank: In animal cells, protein filaments tighten between the two daughter cells to form a _____________________.

4.4 The process of cytokinesis involves the division of which two parts of the cell?

Mitosis Review Answers Go Back

Prophase: Chromosomes condense, nuclear membrane breaks apart, mitotic spindle forms and attaches to sister chromatids

Metaphase: Sister chromatids line up along the middle of the cell

Anaphase: Sister chromatids are separated and one complete set of chromosomes is pulled to opposite ends of the cell

Telophase: Spindle fibers disassemble and a nuclear membrane forms around each set of chromosomes * Cytokinesis is occurring at the same time

Interphase: Chromosomes are loose and not condensed; the cell is growing and preparing for another division

Congratulations!

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You have completed the Virtual Mitosis Lab!!!!

You should have now completed all of the question on your Lab Report. If you have missed some questions, use the “Go Back” link above to return

to the lab. Look for the “?” symbol to find all Lab Report questions.