Chapter 12, 13 Mitosis Lecture

Question 1

1. G1 phase involves cell growth and normal cellular functions.
2. S phase is when DNA replication occurs.
3. G2 phase is a checkpoint phase where the cell prepares for mitosis by making necessary proteins and organelles.
4. M phase is when mitosis and cytokinesis occur.

Answer 1

G1 phase involves cell growth and normal cellular functions.
S phase is when DNA replication occurs.
G2 phase is a checkpoint phase where the cell prepares for mitosis by making necessary proteins and organelles.
M phase is when mitosis and cytokinesis occur.

Question 2

The ______ is replicated in the S Phase and forms the mitotic spindle during Mitosis.

Answer 2

centrosome

Question 3

During S Phase, cells replicate their DNA & the ______.
______:A cytoplasmic protein complex that forms/organizes the mitotic spindle during Mitosis.

Answer 3

During S Phase, cells replicate their DNA & the centrosome.

Question 4

Centrosome: A cytoplasmic protein complex that forms/organizes the ________ during Mitosis.

________: Microtubule proteins of the cytoskeleton that coordinate the division of chromosomes

Answer 4

Centrosome: A cytoplasmic protein complex that forms/organizes the mitotic spindle during Mitosis.

Mitotic Spindle: Microtubule proteins of the cytoskeleton that coordinate the division of chromosomes

Question 5

What is the name of the microtubule-organizing center found in animal cells as an identifiable structure present during all phases of the cell cycle?
a) Spindle.
b) Centromere.
c) Centrosome.
d) Kinetochore.

Answer 5

c) Centrosome.

The centrosome is the microtubule-organizing center found in animal cells and is present during all phases of the cell cycle.

Question 6

What is the role of the spindle fibers during mitosis?
a) They separate the chromosomes.
b) They break down the nuclear envelope.
c) They replicate the DNA.
d) They condense the chromosomes.

Answer 6

a) They separate the chromosomes.

Spindle fibers attach to chromosomes at their kinetochores and help pull the sister chromatids apart during mitosis, ensuring accurate chromosome segregation.

Question 7

____: the asexual process of dividing the nucleus and the genetic material of a somatic (body) cell.

Starts with one diploid cell and ends with \_\_\_ genetically identical \_\_\_\_\_ cells.

Answer 7

Mitosis: the asexual process of dividing the nucleus and the genetic material of a somatic (body) cell.

Starts with one diploid cell and ends with two genetically identical diploid cells.

Question 8

Mitosis consists of five different phases:

Answer 8

Prophase, Prometaphase, Metaphase, Anaphase, and Telophase.

Question 9

1) Prophase
●Loosely coiled chromatin condenses to form distinct chromosomes with sister chromatids linked at the ___.
□ The nucleolus (location of ribosome synthesis) ____________________ from the nucleus.
□ The two centrosomes migrate to opposite poles of the cell & begin forming the_____ _____.

Answer 9

Loosely coiled chromatin condenses to form distinct chromosomes with sister chromatids linked at the centromere.

The nucleolus (location of ribosome synthesis) disappears from the nucleus.

The two centrosomes migrate to opposite poles of the cell and begin forming the mitotic spindle

Question 10

2) Prometaphase
●Prometaphase is also sometimes referred to as “___________” prophase.
□ Nuclear Envelope __________________, exposing chromosomes to the cytoplasm.
□ Mitotic spindle links to chromosomes by attaching to ______________________ proteins in the centromere.

Answer 10

Prometaphase is also sometimes referred to as “late” prophase.

The nuclear envelope disintegrates, exposing chromosomes to the cytoplasm.

The mitotic spindle links to chromosomes by attaching to kinetochore proteins in the centromere.

Question 11

The phase of mitosis where chromosomes condense and centrosomes move to opposite poles of the cell is:
a) Prometaphase.
b) Metaphase.
c) Prophase.
d) Anaphase.
e) Telophase.

Answer 11

c) Prophase

During Prophase, chromosomes condense and become visible, and the centrosomes begin to move to opposite poles of the cell.

Question 12

Why does the nuclear envelope break down during prometaphase?
a) To allow the chromosomes to condense.
c) To allow the mitotic spindle to form.
b) To allow the sister chromatids to form.
d) To allow spindle fibers to attach to chromosomes.

Answer 12

d) To allow spindle fibers to attach to chromosomes.

During Prometaphase, the nuclear envelope breaks down, allowing the spindle fibers to access and attach to the chromosomes at their kinetochores. This is a crucial step for proper chromosome alignment and separation.

Question 13

The mitotic spindle plays a critical role in which of the following processes of cellular division?
a) Splitting the cytoplasm following mitosis.
c) Dissolving the nuclear membrane.
b) Triggering the condensation of chromosomes.
d) Moving the chromosomes within the cell.

Answer 13

d) Moving the chromosomes within the cell.

The mitotic spindle is responsible for moving the chromosomes during mitosis, ensuring they are properly aligned and separated into the two daughter cells. It plays a crucial role in chromosome segregation.

Question 14

During _____, the following occurs:

I. Chromosomes move to the equatorial plane (metaphase plate) of the cell.

II. A spindle fiber attaches to each sister chromatid.

Answer 14

Metaphase

Question 15

Metaphase is characterized by ________.
a) Separation of the sister chromatids.
b) Separation of the cytoplasm.
c) Alignment of chromosomes along the cell’s equator.
d) Alignment of the mitotic spindle along the cell’s equator.

Answer 15

c) Alignment of chromosomes along the cell’s equator.

During Metaphase, chromosomes align at the metaphase plate (the cell’s equator) in preparation for separation, which will occur during Anaphase.

Question 16

4) _____: sister chromatids are pulled apart towards opposite ends of the cell.
□ Some parts of the mitotic spindle shorten, pulling chromatids apart, whereas others lengthen, stretching the cell.

Answer 16

Anaphase

Question 17

In what way do kinetochore microtubules facilitate the process of splitting the sister chromatids?
a) They use motor proteins to hydrolyze the centromere at specific arginine residues.
b) They create tension by pulling toward opposite poles.
c) They slide past each other like actin microfilaments.
d) They phosphorylate the centromere, thereby changing its conformation.

Answer 17

b) They create tension by pulling toward opposite poles.

Question 18

Which of the following is a function of the non-kinetochore microtubules?
a) Maintaining an appropriate spacing among the moving chromosomes.
b) Starting the separation of the cytoplasm once the final stage of mitosis is complete.
c) Providing the ATP needed by the kinetochore microtubules to move the chromosomes.
d) Pulling the poles of the cell closer together.
e) Pushing the poles of the cell further apart.

Answer 18

e) Pushing the poles of the cell further apart.

Question 19

5)______: The final step of mitosis, practically the reverse of prophase & prometaphase.
□ Chromosomes begin to ____________ back to its loose, ________________ state.
□ Mitotic spindle _________________.
□ Nucleolus & nuclear envelope _______________ at each end of the cell to form _______ nuclei.
This process prepares the cell for the final division (______).

Answer 19

Telophase
uncoil
chromatin
disassembles
reform
two
cytokinesis

Question 20

The nuclear envelopes form and the mitotic spindles disassembles during telophase in preparation for what?
a) The merging of the two nuclei.
b) The division of the cell into two daughter cells, each with their own nuclei.
c) The division of the cell into four daughter cells, each with half a nuclei.
d) Nothing, the cell now possesses two nuclei and twice the amount of genetic material.

Answer 20

b) The division of the cell into two daughter cells, each with their own nuclei.

Question 21

At which phase of the cell cycle do centrosomes begin to move apart in animal cells?
a) Anaphase.
b) Metaphase.
c) Telophase.
d) Prophase.

Answer 21

d) Prophase.

Question 22

If there are 40 centromeres in a cell at anaphase of mitosis, how many chromosomes will be found in each daughter cell following cytokinesis?
a) 10. b) 20. c) 40. d) 80.

Answer 22

b) 40.

During anaphase, the sister chromatids are separated, so each daughter cell will receive an equal number of chromosomes, which is 40 in this case.

Question 23

Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol prevents microtubule depolymerization (breaking down). Thus, Taxol stops mitosis by interfering with which ofthe following structures or processes?
a) The mitotic spindle.
b) Cytokinesis.
c) DNA replication.
d) Chromosome condensation.

Answer 23

a) The mitotic spindle.

Microtubules form the mitotic spindle, and Taxol interferes with their ability to depolymerize, which is essential for chromosome movement during mitosis.

Question 24

Mitosis divides the nucleus but is followed by ______________________ to produce two identical daughter cells.
□ _______: division of the ___________________, separating one cell into two cells.
□ Animal & plant cell cytokinesis ____________ in their mechanism.

Answer 24

Cytokinesis, Cytokinesis, cytoplasm, differ

Question 25

Why is cytokinesis an important part of cell division? a) It is responsible for the proper separation of genetic information. b) It is responsible for the proper separation of the cytoplasmic contents. c) It is responsible for the linking of two sister chromatids. d) It is responsible for the growth & production of new organelles & other cytoplasmic contents.

Answer 25

b) It is responsible for the proper separation of the cytoplasmic contents. Cytokinesis is the final step of cell division where the cytoplasm and organelles are equally distributed into the two daughter cells, ensuring that each new cell has the necessary components to function properly.

Question 26

●Cell division is controlled/activated by a variety of cellular signals in the form of proteins called _____________ factors. □ Growth factor: a biological substance that ________________ cell division. ●Also, multiple Cell Cycle “___________________” prevent the cell from entering the next phase prematurely. □ If an error is detected at any checkpoint, a protein called p53 can trigger repair or _______________ (cell death). □ A cell that “ignores” cell cycle checkpoints can lead to _________________.

Answer 26

Cell division is controlled/activated by a variety of cellular signals in the form of proteins called regulatory factors. □ Growth factor: a biological substance that stimulates cell division. ●Also, multiple Cell Cycle checkpoints prevent the cell from entering the next phase prematurely. □ If an error is detected at any checkpoint, a protein called p53 can trigger repair or apoptosis (cell death). □ A cell that “ignores” cell cycle checkpoints can lead to cancer.

Question 27

4 major checkpoints control the progress of the Cell Cycle: G1 Checkpoint: The cell fixes damaged/mutated DNA in preparation for DNA replication in the S phase. G2 Checkpoint: Confirms proper replication of genetic material and attempts to fix any errors. M Checkpoint: Ensures all enzymes and proteins needed for mitosis and cytokinesis are available. (Metaphase) Checkpoint: Confirms that all chromosomes are aligned and spindle fibers are attached properly.

Answer 27

4 major checkpoints control the progress of the Cell Cycle: G1 Checkpoint: The cell fixes damaged/mutated DNA in preparation for DNA replication in the S phase. G2 Checkpoint: Confirms proper replication of genetic material and attempts to fix any errors. M Checkpoint: Ensures all enzymes and proteins needed for mitosis and cytokinesis are available. (Metaphase) Checkpoint: Confirms that all chromosomes are aligned and spindle fibers are attached properly.

Question 28

What is the purpose of cell cycle checkpoints? a) To coordinate a cell’s specialization for its role in particular tissues. b) To prevent the cell from pausing the cell cycle when problems are detected. c) To ensure that cells containing errors in their DNA do not undergo apoptosis. d) To coordinate movement of vesicles through the cell. e) To ensure that a cell only proceeds to the next phase in the cell cycle if it is ready.

Answer 28

e) To ensure that a cell only proceeds to the next phase in the cell cycle if it is ready.

Question 29

Checkpoints within the cell cycle: a) Are located within interphase and allow entry to G0. b) Are located within G1, S and G2. c) Are located within G1, M and G2. d) Are located within G1, M, S and G2. e) Are located within all the phases of the cell cycle.

Answer 29

Checkpoints within the cell cycle: d) Are located within G1, M, S, and G2.

Question 30

The M phase checkpoint ensures that all chromosomes are attached to the mitotic spindle. If this does not happen, cells would most likely be arrested in ________. a) Telophase. b) Prophase. c) G2. d) Metaphase.

Answer 30

The M phase checkpoint ensures that all chromosomes are attached to the mitotic spindle. If this does not happen, cells would most likely be arrested in: d) Metaphase.

Question 31

Which of the following cell cycle checkpoints ensures that the genetic material is fully replicated before mitosis? a) G0. b) M. c) G1. d) G2. e) S.

Answer 31

d) G2. During the G2 phase checkpoint, the cell verifies that DNA replication in the S phase has been completed correctly before it proceeds to mitosis.

Question 32

Movement of the chromosomes during anaphase would be most affected by a drug that: a) Prevents the formation of a cleavage furrow. b) Prevents the formation of the nuclear envelope. c) Prevents elongation of microtubules. d) Prevents shortening of microtubules.

Answer 32

d) Prevents shortening of microtubules. During anaphase, the sister chromatids are pulled toward opposite poles of the cell by the shortening of kinetochore microtubules. A drug that prevents the shortening of microtubules would interfere with this process and disrupt the movement of chromosomes during anaphase.

Question 33

_____is the final step of cell division where the cytoplasm and organelles are equally distributed into the two daughter cells, ensuring that each new cell has the necessary components to function properly.

Answer 33

Cytokinesis