Question

1. refer to model 1.

a. in which phase of mitosis do you see the spindle fibers forming?
b. at what phase of mitosis do the replicated chromosomes (sister chromatids) separate?
c. in which phase do you see that the spindle fibers have disappeared?
d. look at metaphase and anaphase. suggest the purpose of the spindle fibers during mitosis.

1. refer to model 1.

a. describe what happens to the nuclear membrane after prophase.
b. explain why it is necessary that the nuclear membrane disintegrates during mitosis.
c. at what point during mitosis has the nuclear membrane reformed?

1. what is actually dividing during cytokinesis?
2. cellular division has two parts—mitosis is the division of the nucleus and cytokinesis is the division of the cell into two new cells. explain why mitosis has to come before cytokinesis in the cell cycle.
3. during cytokinesis the chromosomes unwind and become a pile of very long, thin, thread - like dna and the cell goes back to looking

ormal\ until mitosis begins again. brainstorm with your group ideas why the dna must coil up into chromosome structures before it divides.

Explanation:

For Question 12:

a. Spindle fibers start forming early in mitosis as the cell prepares chromosome movement.
b. Sister chromatids separate when spindle fibers pull them apart.
c. Spindle fibers break down as mitosis concludes and the cell resets.
d. Spindle fibers align chromosomes first, then pull them apart to ensure even distribution.

For Question 13:

a. The nuclear membrane breaks down after prophase to allow spindle access.
b. Disintegration removes a barrier for spindle fibers to interact with chromosomes.
c. The nuclear membrane reforms around new chromosome sets at the end of mitosis.

For Question 14:

Cytokinesis focuses on splitting the cell's non-nuclear components to form two cells.

For Question 15:

Mitosis ensures genetic material is duplicated and split evenly first, so each new cell gets a complete, identical set of chromosomes.

For Question 16:

Coiling DNA into chromosomes organizes the long, fragile DNA, preventing tangling and ensuring each new cell gets an exact copy without damage.

Answer:

12.
a. Prophase
b. Anaphase
c. Telophase
d. Spindle fibers align chromosomes at the cell's equator during metaphase, then pull sister chromatids apart to opposite poles during anaphase, ensuring each new nucleus receives an identical set of chromosomes.

13.
a. The nuclear membrane disintegrates (breaks down) after prophase.
b. The nuclear membrane must disintegrate to allow spindle fibers to access and attach to the chromosomes, which is necessary for moving chromosomes during mitosis.
c. Telophase (the final phase of mitosis)

1. The cytoplasm (along with the cell membrane and other cytoplasmic organelles) is dividing during cytokinesis, splitting the parent cell into two genetically identical daughter cells.

1. Mitosis must come before cytokinesis because it ensures the cell's genetic material (chromosomes) is duplicated and evenly separated into two identical sets. Cytokinesis then splits the cell around these two new nuclei, so each daughter cell receives a complete, identical copy of the genetic material. If cytokinesis happened first, the genetic material would not be properly distributed.

1. DNA coils into chromosomes before division for three key reasons:
2. To organize the very long, thin DNA strands into compact structures that can be easily moved and separated without tangling or breaking.
3. To ensure that each sister chromatid (and thus each daughter cell) receives an exact, complete copy of the genetic material.
4. To protect the fragile DNA from damage during the physical process of chromosome movement and cell division.