Chapter Review.

1. What chemicals regulate the cell cycle? How do they work?
Cyclins, which are proteins that fluctuate in concentration at specific points during the cell cycle and that regulate the cycle by binding to a kinase.

2. What happens when cells do not respond to the signals that normally regulate their growth?
Cancer cells are malignant growth caused by abnormal and uncontrolled cell division; it may spread to other parts of the body through the lymphatic system or the blood stream, which can severely damage surrounding tissue.

3. How do cells respond to contact with other cells?
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 can result in the yielding of cell production or the over-production.

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



1. Name the main events of the cell cycle:
A cell grows and develops, prepares for division, and then divides to form two "daughter" cells. This process is continuous.

2. Describe what happens in each of the four phases of the cell cycle:
Prophase:
The first stage of mitosis, during which the chromosomes condense and become visible, the nuclear membrane breaks down, and the spindle apparatus forms at opposite poles of the cell.
The first stage of meiosis, during which the DNA replicates, homologous chromosomes undergo synapsis, chiasmata form, and the chromosomes contract.
Metaphase:
The stage of mitosis and meiosis, following prophase and preceding anaphase, during which the chromosomes are aligned along the metaphase plate.
Anaphase:
The stage of cell division in mitosis or meiosis in which the doubled set of chromosomes separates into two identical groups that move to opposite ends of the cell. Anaphase is preceded by metaphase and followed by telophase.
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.


3. Describe what happens during interphase.
The stage in the cell cycle when the cell is not dividing and during part of which DNA replication occurs; it follows telophase of one mitotic division and extends to the beginning of prophase in the next division.

4. What are chromosomes made of?
Chromosomes are conformed of a pair of "sister" chromatids attached by a centromere.

5. How do prokaryote cells divide?
Prokaryotic cells divide by a process called cell division or mitosis.

6. How is cytokinesis in plant cells similar to cytokinesis in animal cells? How is it different?
In an animal cell, the cell membrane implodes until it releases the cytoplasm, where in the plant cell, division takes a different process where a "cell plate" is developed in the center of the cell.


1. Give two reasons why cells divide:
There are two reasons cells divide: Cell growth and DNA "overload."
2. How is a cells DNA like the books in a library?
Like the production of books, the rapid production of cells will cause a delay in the demand of more.

3. What is the solution to the problems in cell growth?
Cell Divison.

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

5. Calculate the surface area, volume, and ratio of surface area volume of an imaginary cubic cell with a length of 4 cm.
Surface area: 92cm squared
Volume: 64cm cubed
Ratio: 92/64.