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The rate at which materials enter and leave through the cell membrane depends on the cell’s… |
surface area |
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The process of cell division results in… |
two daughter cells |
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Sister chromatids are attached to each other at an area called the… |
centromere |
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If a cell has 12 chromosomes, how many chromosomes will each of its daughter cells have after mitosis? |
12 |
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At the beginning of cell division, a chromosomes consists of two… |
chromatids |
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The phase of mitosis during which chromosomes become visible and the centrioles separate from one another is… |
prophase |
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What illustration best represents metaphase of mitosis? |
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The timing of the cell cycle is eukaryotic cells is believed to be controlled by a group of closely related proteins known as… |
cyclins |
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In the cell cycle, external regulators direct cells to… |
speed up or slow down the cell cycle |
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Uncontrolled cell division occurs in… |
cancer |
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Summarize what happens during the process of cell division. |
a cell divides into two new daughter cells |
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Explain how a cell’s DNA can limit the cell’s size. |
When a cell is small, the information stored in its DNA is able to meet all of the cell’s needs. But if a cell were to grow without limit, an "information crisis" would occur. |
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Describe what is meant by cell volume. |
the amount of material inside the cell |
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Describe what is meant by cell surface area. |
the total area of the cell’s membrane |
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Describe what is meant by ratio of surface area to volume. |
the surface area divided by the volume |
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How is a cell’s potential growth affected by its ratio of surface area to volume? |
A cell’s ratio of surface area to volume decreases as it grows larger. This means that the area available for diffusion also decreases. Thus, if a cell grows too large, it is unable to take in all needed materials and expel all its wastes. These problems impose limits on the growth of the cell. |
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Describe how a cell’s chromosomes change as a cell prepares to divide. |
Well before cell division, each chromosome is replicated. At the beginning of cell division, each chromosome consists of two identical sister chromatids. |
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What is the relationship between interphase and cell division? |
Together, interphase and cell division make up the cell cycle. |
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Summarize what happens during interphase. |
A cell increases in size, synthesizes new proteins and organelles, replicates its chromosomes, and prepares for cell division by producing needed spindle proteins. |
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Explain how the following terms are related to one another: |
The genetic information that is passed on from one generation of cells to the next is carried by chromosomes, which are made up of DNA. Before cell division, chromosomes are replicated, so that each chromosome consists of two identical "sister" chromatids. Sister chromatids are attached at an area called the centromere. |
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List the following events in the correct sequence, and describe what happens during each event: |
Prophase: Chromatin condenses into chromosomes; centrioles separate; spindle begins to form; nuclear membrane breaks down. Metaphase: Chromosomes line up across middle of cell with spindle fibers connected to their centromeres. Anaphase: Sister chromatids separate and move apart. Telaphase: Chromosomes gather at opposite ends of cell and lose distinct shape; new nuclear membranes form |
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How does the number of chromosomes in the two new cells compare with the number in the original cell at the end of cell division? |
The number of chromosomes in each of the two cells equals the number in the original cell. |
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Summarize what happens during the cell cycle. |
A cell grows, prepares for division, and divides to form two daughter cells, each of which then begins the cycle again. |
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When some cells are removed from the center of a tissue culture, will new cells replace the cells that were removed? Explain |
Yes, new cells will replace the removed cells because of the process of cell division, which will continue until the new cells come in contact with other cells. When that occurs, cell division will stop. |
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Describe the role of cyclins in the cell cycle. |
they regulate the timing of the cell cycle in eukaryotic cells. |
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Why is it important that cell growth in a multi-cellular organism be regulated so carefully? |
The consequences of uncontrolled cell growth are severe, as in cancer, for example. |
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How do cancer cells differ from noncancerous cells? |
Cancer cells do not respond to the signals that regulate the growth of most cells. As a result, they form masses of cells called tumors that can damage the surrounding tissues |
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