Biology CH 10 – Flashcards
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What happens during an information crisis
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as the cell grows, the information does too. However the DNA, which stores the information doesn't grow, so there is too much information in the cell
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other than too much information, why is cell size limited
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Because the rate at which food and oxygen are used up and wasste is produced depends on the cell's volume.
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surface area formula
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(length X width)
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volume formula
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(length X width X height)
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What happens as a cell continues to grow
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as a cell continues to grow, it becomes more difficult to get sufficient amounts of oxygen and nutrients in and waste products out.
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cell division
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the process by which a cell divides into two new daughter cells
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what happens before cell division occurs
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before cell division occurs, the cell replicates, and copies all of its DNA. This replication of DNA solves the problem of information overload because each daughter cell gets one set of genetic information. It also solves the problem of increasing size by reducing cell volume.
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reproduction
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the formation of new individual
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How do asexual and sexual reproduction compare?
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The production of genetically identical offspring from a single parent is known as asexual reproduction. Offspring produced by sexual reproduction inherit some of their genetic information from each parent.
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asexual reproduction
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when two cells are produced by cell division and are genetically identical to the cell that produced them; occurs in many multicellular organisms
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sexual reproduction
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involves the fusion of two separate parent cells; during this an offspring is produced by the fusion of special reproductive cells formed by each of two parents
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most ____________ and plants reproduce sexually and most _____________________ reproduce asexually
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animal; single celled organisms
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What are some pros and cons of asexual reproduction
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pro: for some organisms, it is a survival strategy because it betters their chance of survival over other organisms pro: having genetically identical offspring is an advantage as long as conditions remain favorable pro: very quick con: if conditions change in ways that no longer fit the organism that is bad
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Why is sexual reproduction important
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con: takes more time pro: the time it takes is good for species that live in environments where seasonal changes effect weather and food availability pro: provides genetic diversity
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What is an organism that reproduce asexually and sexually
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yeast (mostly asexually though)
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What is the role of chromosomes in cell division?
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Chromosome make it possible to separate DNA precisely during cell division.
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Why can't you split a cell in half without preparation. What do cells do instead?
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This can't happen because the DNA might end up unevenly in the cells. Before splitting, the cells make a complete copy of their genetic information before the division begins.
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chromosomes
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packages of DNA that genetic information is bundled into
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Where is DNA found in Prokaryotes?
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Prokaryotes lack nuclei and many of the organelles found in eukaryotes, so their DNA molecules are found in the cytoplasm along with most of the other contents of the cells. These cells usually contain a single, circular DNA chromosome that has all or the cell's genetic information.
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chromatin
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the complex of chromosome and protein in eukaryotic cells
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nucleosomes
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these are produced when DNA tightly coils around the histones; beadlike structures that then pack together to form thick fibers, which condense even further during cell division.
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What is the chromosome shape we usually see?
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This is a duplicated chromosome with supercoiled chromatin
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Why do cells go to such lengths to package their DNA in chromosomes?
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This is because it ensures equal division of DNA when a cell divides
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What are the events of the prokaryote cell cycle
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During the cell cycle, a cell grows, prepares for division, and divides to form two daughter cells. Each daughter cell then moves into a new cell cycle of activity, growth, and division.
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cell cycle
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a series of events that cells go through as they divide
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prokaryotic cell cycle
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a regular pattern of growth, DNA replication, and cell division that take place very rapidly
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The eukaryotic cell consists of four phases
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1. G1 2. S 3. G2 4. M
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interphase
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the period of growth in cell division; this is the first three steps of the cell phases
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G1 Phase
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this is the cell growth phase. Here cells increase in size and synthesize new proteins and organelles. The "G" stands for gap but this and the other "G" phase are periods of intense growth and activity
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S Phase
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this is the cell's DNA replication phase. Here the cells synthesize the DNA and the chromosomes are replicated. At the end of this, there should be twice as much DNA; the "s" stands for synthesis.
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G2 Phases
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this phase is the cells preparation for cell division. Here many of the organelles and molecules required for cell division are produced. It is the shortest phase, and the end of interphase
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M phase
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this phase it the cell division. The "m" stands for mitosis. The first stage of this is mitosis, which is the division of the cell nucleus. The second stage is called cytokinesis, which is the division of the cytoplasm. Often cytokinesis begins while mitosis is taking place. This is a short phase.
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mitosis
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part of eukaryotic cell division during which the cell nucleus divides
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What events occur during each of the four phases of mitosis?
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During prophase, the genetic material inside the nucleus condenses and the duplicated chromosomes become visible. Outside the nucleus, a spindle begins to form. During metaphase, the centromeres of the duplicated chromosomes line us across the center of the cell. Spindle fibers connect the centromere of each chromosome to the two poles of the spindle. During anaphase, the chromosomes separate and move along spindle fibers to opposite ends of the cell. During telophase, the chromosomes, which were distinct and condensed, begin to spread out into a tangle of chromatin.
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-mitosis, the second phase of the m phase, can last anywhere from a few minutes to several days. What are its phases called?
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1. Prophase 2. Metaphase 3. Anaphase 4. Telephase
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prophase
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the longest phase; during this the genetic material condenses, chromosomes begin to show, and a spindle starts to form.
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centromere
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the area where duplicated strands of the DNA molecules that are seen are attached to
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chromatid
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also called sister chromatid; each DNA strand in the duplicated chromosome; after mitosis, these are separated and divided between the new daughter cells
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spindle
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a fanlike system of microtubules that help to separate the duplicated chromosomes.
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spindle fibers
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these extend from a region called the centrosome
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centrioles
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tiny paired structures located on the centrosome; not in plant cells
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centrosome
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region where spindle fibers and centrioles are located.
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What happens as prophase ends?
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The chromosomes coil more tightly, the nucleolus disappears, and the nuclear envelope breaks down
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metaphase
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the shortest phase of mitosis, where the centromeres line up across the center of the cells and the spindle fibers connect each of these to each of the two poles of the spindle
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anaphase
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this phase begins when sister chromatids separate and move apart. These are considered an individual chromosome. When this movement stops and the chromosomes are completely separated, this phase is over
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telophase
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this is the final phase, where a nuclear envelope re-forms around each cluster of chromosomes. The spindle then breaks apart and a nucleolus becomes visible in each nucleus. Now mitosis is complete
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How do daughter cells split apart after mitosis?
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Cytokinesis completes the process of cell division-it splits one cell into two
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cytokinesis in animal cells
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the cell membrane is drawn inward until the cytoplasm is pinched into equal parts, that each contain a nucleus and cytoplasmic organelles
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How does cytokinesis occur in plant cells?
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Because the cell membrane isn't flexible enough to draw inward because of the rigid cell wall that surrounds it, the cell plate must form halfway between the divided nuclei. The cell plate develops into cell membranes that separate the two daughter cells. A cell wall tehn forms in between the two new membranes
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How is the cell cycle regulated?
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The cell cycle is controlled by regulatory proteins both inside and outside the cell.
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What happens when cells come into contact with each other?
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They stop dividing and growing. This was tested when scientists were growing cells in the laboratory. When the cells came into contact, they stopped growing and dividing. The neighboring cells were then scraped off, and the cells began dividing and growing again. This shows that controls on cell growth and division can be turned on and off.
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What happens when you get and injury?
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When an injury occurs, cells at the edge of the injury are stimulated to divide rapidly. New cells for, and when the healing process nears completion, the rate of cell division slows, controls on growth are restored, and everything remains normal
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cyclin
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a protein that regulates the cell cycle. When it is injected into a non-dividing cell, a mitotic spindle forms.
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internal regulatory proteins
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proteins that respond to event occurring inside a cell. These make sure the cell cycle happens in order, like keeping the cell from mitosis till the DNA is duplicated
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external regulatory proteins
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proteins that respond to events outside the cell; these direct cells to speed up or slow down the cell cycle.
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growth factors
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these proteins are a group of external regulatory proteins. They stimulate the growth and division of cells. They are important especially during the embryonic development and would healing.
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Other than the grow factors group, what do the external regulatory proteins do?
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They cause cells to slow down or stop their cells. This prevents excessive cell growth and keeps body tissues from disrupting one another.
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Why do cyclins do within cells?
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Cyclins are continually produced and destroyed within cells. Cyclin production signals cells to enter mitosis, while cyclin destruction signals cells to stop dividing and enter interphase
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What two ways do cells end their life cycle
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a cell may die by accident due to damage or injury, or a cell may go through apoptosis (be programmed to die)
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Apoptosis
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a process of programmed cell death; once triggered, the cell undergoes a series of controlled steps leading to its self-destruction
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What are the parts of apoptosis?
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First the cell and its chromatin shrink, then parts of the cell's membranes break off. Neighboring cells then quickly clean up the cell's remains
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Why is apoptosis important?
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it shapes the structure of tissues and organs in plants and animals. Like the gap between toes is like that because apoptosis occurs. When this doesn't occur properly, a number of diseases, like Parkinson's disease, can result
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How do cancer cells differ from other cells?
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Cancer cells do not respond to the signals that regulate the growth of most cells. As a result, the cells divide uncontrollably.
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Why is cell growth regulated so carefully?
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This is because the consequences of uncontrolled cell growth in a multicellular organism are very severe. Cancer is an example of this
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cancer
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a disorder in which body cells lose the ability to control growth
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tumor
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a mass of cells where cancer cells form. Not all tumors are cancerous. There are two types, cancerous and benign (noncancerous)
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benign tumor
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this is a tumor that is noncancerous. It does not spread to surrounding healthy tissues or to other parts of the body.
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cancerous tumor
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these have malignant tissues, which invade and destroy surrounding healthy tissue.
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malignant tissues
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invades and destroys surrounding healthy tissue
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What happens as cancer cells spread?
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They absorb the nutrients needed by other cells, they block nerve connections, and they prevent the organs they invade from functioning properly. Soon, the delicate balances that exist in the body are disrupted, and life-threatening illness results.
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What causes cancer?
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Cancers are caused by defects in the genes that regulate cell growth and division. There are several sources of such defects: smoking or chewing tobacco, radiation exposure, other defective genes, and even viral infection.
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What are the parts of the growth of cancer cells?
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1. A cell begins to divide abnormally (because of defects in the genes) 2. The cancer cells produce a tumor, which begins to displace normal cells and tissues 3. Cancer cells are dangerous because they have a tendency to spread once they enter the bloodstream or lymph vessels. The cancer then moves into other parts of the body and forms secondary tumors
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metastasis
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the process during which cancer cells move into other parts of the body and for secondary tumors
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How do cancer cells affect the cell cycle?
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The control over the cell cycle has broken down when cancer is present. Some cancer cells will no longer respond to external growth regulators, while others fail to produce the internal regulators that ensure orderly growth.
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p53
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this gene halts the cell cycle until all chromosomes have been properly replicated. If these are damaged or defective, they cause cells to lose the information needed to respond to signals that normally control their growth.
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What are some treatments for cancer
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surgery radiation chemotherapy
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surgery on cancer
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when a cancerous tumor is localized, it can be removed by surgery (skin cancer)
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radiation on cancer
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this needs to be a carefully targeted beam. It works because cancer cells copy their DNA more quickly than normal cells do, and are especially vulnerable to damage from radiation.
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chemotherapy on cancer
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this is the use of compounds against cancer. This is a highly researched process and it is even able to cure some forms of cancer. The only downside is that because most chemotherapy compounds target rapidly dividing cells, they also interfere with cell division in normal, healthy cells, so there are many side effects.
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