Chapter 10 Questions

Page 243.



1. Give two reasons why cells divide.

Cells divide because the larger the cell becomes, the more demands the cell puts on the DNA. Again, the larger the cell becomes, the more trouble the cell has moving enough wastes and nutriends through the cell membrane.



2. How is a cell's DNA like the books in a library?

DNA may not be able to meet the needs of a growing cell because it would put greater demands on the "library". This would relate to books in a library because the more cutsomers there are, the more books the library would have to carry for the customers needs.



3. What is the solution to the problems caused by cell growth?

The soultion to the problems caused by cell growth is cell division.



4. As a cell increases in size, which increases more rapidly, its surface area or volume?

The surface area of a cell increases more rapidly then the volume.



5. Calculate the surface area, volume, and ratio of surface area to volume of an imaginary cubic cell with a length of 4 cm.

surface area: 4cm X 4cm X 6= 96cm

volume: 4cm X 4cm X 4cm= 64 cm (^3)

Ratio of surface area to volume: 96/64= 96 : 64



Page 249.



1. Name the main events of the cell cycle.

G1, S, G2.



2. Describe what happens during each of the four phases of mitosis.

Prophase- longest phase, chromosomes become visible, centrioles seperate and go to opposite sides of the nucleus.

Metaphase- chromosomes line up accross the center of the cell and the microtubules connect the centromere of each chromosome to the spindle poles.

Anaphase- centromeres join the sister chromatids seperate and allow become individual chromosomes, they move to either poles then keep moving until this phase is over.

Telophase- last phase, chromosomes disperse into dense material, the nuclear envelope reforms, and the nucleolus becomes visible in each daughter nucleus.



3. Describe what happens during interphase.

Interphase is the "in-between" period of cell growth. During this time, the cell cycle occurs.



4. What are chromosomes made of?

Chromosomes are a threadlike structure in the nucleus that contains the genetic information that is passed between cell generations.



5. How do prokaryotic cells divide?
Prokaryotes divide by mitosis.

6. How is cytokinesis in plant cells similar to cytokinesis in animal cells? How is it different?
In animal cells, the cell membrane is drawn inward until the cytoplasm is splint into two nearly equal parts. Then each part has its own nucleus and organelles. In plant cells, the cell plate forms midway between the divided nuclei. Then the cell plate gradually develops into a serperate membrane and a cell wall is built. The similarity between division in plant and animal cells is that there is a splitting of something.

Page 252
1. What chemicals regulate the cell cycle? How do they work?
Protein (cyclin) regulates the cell cycle. There are internal regulators and external regulators. Internal regualtors respond to events inside the cell. External regulators respond to events that are outside of the cell.

2. What happens when cells do not respond to their signals that normally regulate their growth?
The cells become cancerous when they do not respond to the signals.

3. How do cells respond to contact with other cells?
The standard procedures could be interrupted and the cell cycle could be thrown off.

4. Why can cancer be considered a disease of the cell cycle?
Cancer can be considered a disease of the cell cycle because the cell cycle's process is damaged and it can result in the slowing or stopping of cell production or the over-production.

5. Write a hypothesis about what you think would happen if cyclin were injected into a cell that was in mitosis.
If a cell already in mitosis were injected with cyclin, the internal regulators would start to over-produce, because cyclin regulates speed, but the cell has already gained its own speed.

Page 257
1. The rate at which marierals enter and leave the cell through the cell membrane depends on the:
a) volume.

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:
b) centromere.

4. If a cell has 12 chromosomes, how many chromosomes will each of its daughter cells have after mitosis?
b) 6.

5. At the beginning of cell division, a chromosome constists of two:
c) chromatids.

6. The phase of mitosis during which chromosomes become visible and the centrioles seperate is:
a) prohpase.

7. Metaphase is best illustrated in which figure?
b.

8. The timing of the cell cylce in eukaryotic cells is controlled by a group of closly related proteins known as:
b) cyclins.

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

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

Cell Growth and Division Vocab

cell division: the division of a cell in reproduction or growth.
http://youtube.com/watch?v=wYRuhm4SNyA
chromatid: one of two identical strands into which a chromosome splits during mitosis.
http://www.plyojump.com/courses/biology/images/chromosome_chromatid_split.jpg
centromere: a specialized structure on the chromosome, appearing during cell division as the constricted central region where the two chromatids are held together and form an X shape.
www.lbl.gov/.../2001/Jan-02-2002/kinetochore.jpg
interphase: the period of the cell cycle during which the nucleus is not undergoing division, typically occurring between mitotic or meiotic divisions.
http://botit.botany.wisc.edu/images/130/Meiosis/Lilium_microsporogenesis/Interphase.low.jpg
cell cycle: The series of events involving the growth, replication, and division of a eukaryotic cell.
http://youtube.com/watch?v=JmiSg_bEv6I&feature=related
mitosis: The process in cell division by which the nucleus divides, typically consisting of four stages, prophase, metaphase, anaphase, and telophase, and normally resulting in two new nuclei, each of which contains a complete copy of the parental chromosomes.
http://library.thinkquest.org/C0123260/basic%20knowledge/images/basic%20knowledge/cell%20division/mitosis.gif
prophase: the first stage of mitosis or meiosis in eukaryotic cell division, during which the nuclear envelope breaks down and strands of chromatin form into chromosomes.
http://img.sparknotes.com/figures/D/d756b5b73abe2974f3521a828791899f/prophase.gif
centriole: one of a pair of small cylindrical cell organelles near the nucleus in animal cells.
http://sun.menloschool.org/~birchler/cells/animals/centriole/centriole2.jpg
spindle: shaped structure, composed of microtubules, that forms near the cell nucleus during mitosis or meiosis and, as it divides, draws the chromosomes to opposite poles of the cell.
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/spindle.gif
metaphase: the stage in mitosis or meiosis in which the duplicated chromosomes line up along the equatorial plate of the spindle.
http://bvc.kribb.re.kr/download/image/metaphase.gif
anaphase:
the stage in mitosis or meiosis following metaphase in which the daughter chromosomes move away from each other to opposite ends of the cell.
http://img.sparknotes.com/figures/2/29a9dc6524dd09bf44944909a4263dd1/anaphase1.gif
telophase: the final stage of meiosis or mitosis, in which the separated chromosomes reach the opposite poles of the dividing cell and the nuclei of the daughter cells form around the two sets of chromosomes.
http://www.dkimages.com/discover/previews/801/908016.JPG
cytokinesis: The division of the cytoplasm of a cell following the division of the nucleus.
http://img.sparknotes.com/figures/D/d756b5b73abe2974f3521a828791899f/cytokinesis.gif
cyclin: any of a group of proteins active in controlling the cell cycle and in initiating DNA synthesis.http://www.biologyreference.com/images/biol_01_img0070.jpg

cancer: a malignant and invasive growth or tumor, esp. one originating in epithelium, tending to recur after excision and to metastasize to other sites.

http://www.alternative-cancer.net/images/Cancer_cell,%20brain.jpg