Mastering Biology Chapter 12 HW

The is a cell structure consisting of microtubules, which forms during early mitosis and plays a role in cell division.

mitotic spindles

DNA replication produces two identical DNA molecules, called , which separate during mitosis.

sister chromatids

During interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called .

chromatin

Why do some species employ both mitosis and meiosis, whereas other species use only mitosis?

They need both if they are producing plant gametes.

The cell cycle represents the coordinated sequence of events in the life of a cell from its formation to its division into two daughter cells. Most of the key events of the cell cycle are restricted to a specific time within the cycle. In this exercise, you will identify when various events occur during the cell cycle. Recall that interphase consists of the G1, S, and G2 subphases, and that the M phase consists of mitosis and cytokinesis.

a. Non dividing cells exit cell cycle b. At this point cell commits to go through the cycle c. DNA Replicates d. Two centrosomes have formed e. Mitotic spindle begins to form f. Cell divides forming two daughter cells

After chromosomes condense, the is the region where the identical DNA molecules are most tightly attached to each other.

centromeres

The are the organizing centers for microtubules involved in separating chromosomes during mitosis.

centrosomes

In most eukaryotes, division of the nucleus is followed by , when the rest of the cell divides.

cytokinesis

In dividing cells, most of the cell's growth occurs during .

interphase

During mitosis, microtubules attach to chromosomes at the .

kinetochores