Ch. 10 Questions

p. 243 10-1.

1. Cells divide because the larger a cell becomes, the more demands the cell places on its DNA and the more trouble the cell has moving enough nutrients and wastes across the cell membrane.

2. A cells DNA is like the books in a library because they have to make great demands on its available books/genetic information as the town/cell grows.

3. The solution to the problems caused by cell growth is that DNA replication solves the problem of information storage because each daughter cell gets one complete set of genetic information. Cell division also solves the problem of increasing size by reducing cell volume.

4. Each daughter cell has an increased ratio of surface area to volume, so surface area increases more rapidly.

5. Surface Area: 4cm x 4cm x 6= 96cm squared.
Volume: 4cm x 4cm x 4cm= 64cm cubed.
Ratio of surface are to volume: 96/64= 3:2

p. 249 10-2.

1. The main events of the cell cycle are G1, S, and G2.

2. In Prophase, the chromosomes become visible and the centrioles separate and take up positions on the opposite sides of the nucleus. In Metaphase, the chromosomes line up across the center of the cell. In Anaphase, the chromosome pairs separate and move toward opposite poles. In Telophase, the chromosomes begin to disperse into a tangle of dense material.

3. Interphase in the "in between" period that separate divisions. During which, the cell grows and replicates its DNA and centrioles.

4. Chromosomes are made of DNA and chromatids.

5. It copies the DNA and then separates the contents of the cell into two parts.

6. Cytokinesis in plant cells is similar to cytokinesis in animals cells is that they both separate the cytoplasm and that each part of the divided cytoplasm contains its own nucleus and cytoplasmic organelles. They are different in the way that they separate. In plant cells, a cell plate forms in the middle and separates the cytoplasm. In animal cells, the cytoplasm is pinched into two nearly equal parts.

p. 252 10-3.

1. The chemicals that regulate the cell cycle are proteins called cyclins. When cytoplasm from a cell in mitosis is injected into another cell, the second cell enters mitosis. The reason for this effect is a protein called cyclin, which triggers cell division.

2. When cells do not respond to the signals that normally regulate their growth cancer multiplies and causes tumors.

3. When cells come into contact with other cells, they respond by not growing.

4. Cancer is considered a disease of the cell cycle because cancer cells do not respond to the signals that regulate the growth of most cells.

5. If cyclin was injected into a cell that was in mitosis, then it would counteract the cyclin already in the cell and cause all growth to stop and the cell would be left incomplete in its division process, according to what stage mitosis was in at the time.

p. 257 Ch 10 review.

1. The rate at which materials enter and leave through the cell membrabe depends on the cells:
d) Surface area.

2. The process of cell division results in:
c) Two daughter cells.

3. Pairs of identical chromatids are attached to each other at an area called the:
a) Centriole.

4. If a cell has 12 chromosomes, how many chromosomes will each of its daughter cell have after mitosis?
c) 12

5. At the beginning of cell division, a chromosome consists of two:
c) Chromatids.

6. The phase of mitosis during which chromosomes become visible and centrioles separate from one another is:
a) Prophase.

7. Metaphase is best illustrated by:
b)

8. The timing of the cell cycle in eukaryotic cells is controlled by a group of closely related proteins known as:
b) Cyclins.

9. In the cell cycle, external regulators direct cells to:
a) Speed up or slow down the cycle.

10. Uncontrolled cell division occurs in:
a) Cancer.