11.3 eukaryotic cells divide by mitosis

Question 1

Mitosis

Answer 1

-Process of cell division resulting in two genetically identical daughter nuclei.
-Subdivided into prophase, prometaphase, metaphase, anaphase, and telophase.

Question 2

DNA Organization in Mitosis

Answer 2

-DNA molecules bound to proteins form chromatin.
-Condensins coat DNA, making it more compact during mitosis.

Question 3

Chromatin Structure

Answer 3

-DNA molecules organized by histones into nucleosomes.
-Chromosomes are compact and inaccessible to replication and transcription factors during mitosis.

Question 4

Mitosis Steps

Answer 4

-Spindle moves sister chromatids, guided by the centrosome.
-Centrosomes replicate during interphase and move to opposite ends during prophase.

Question 5

Spindle Assembly Checkpoint

Answer 5

-Occurs at metaphase plate; ensures proper chromosome alignment.
-Activates Anaphase-Promoting Complex (APC) for anaphase progression.

Question 6

Anaphase

Answer 6

-Separation of chromatids controlled by M phase cyclin-CDK.
-Cohesin holding chromatids together is hydrolyzed by separase enzyme.

Question 7

Chromatid Separation

Answer 7

-Chromatids become daughter chromosomes after separation.
-Three mechanisms move chromosomes: kinetochore microtubules shorten, centrosomes move apart, and motor proteins like kinesins and dynein act.

Question 8

Cytokinesis

Answer 8

-Division of the cytoplasm following mitosis.
-Animal cells: Cell membrane pinches inward with the help of a contractile ring.
-Plant cells: Vesicles fuse to form a cell plate, which develops into a new cell wall.

Question 9

DNA Replication and Mitosis

Answer 9

-Sister chromatids held together during G2 by cohesins.
-Cohesin removed, except at the centromere, during mitosis.

Question 10

Mitotic Centrosomes

Answer 10

-Two centrioles in centrosome determine the division plane in animal cells.
-Replicate during S phase and move to opposite ends during prophase.

Question 11

Kinetochores and Prometaphase

Answer 11

-Kinetochores develop on each chromatid late in prophase.
-Nuclear envelope breaks down during prometaphase, and the spindle forms.

Question 12

Metaphase

Answer 12

-Chromosomes align at the metaphase plate, controlled by spindle assembly checkpoint.

Question 13

APC Activation

Answer 13

-APC activated when all chromosomes are properly attached to the spindle.
-Inhibits APC if chromosome attachment is improper.

Question 14

Motor Proteins in Mitosis

Answer 14

-Kinesins and dynein motor proteins move chromosomes via kinetochores.
-Kinetochore microtubules shorten to draw chromosomes towards poles.

Question 15

Animal Cell Cytokinesis

Answer 15

Contractile ring of actin and myosin forms to pinch the cell membrane in animal cells.

Question 16

Plant Cell Cytokinesis

Answer 16

-Vesicles from the Golgi apparatus fuse to form a cell plate in plant cells.
-Contents of vesicles form a new cell wall, dividing the cell.