Reading Essentials for Biology Glencoe (794133), страница 23
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This loss of control may be caused by changes inenzyme production inside the cell or by some outside factor, suchas air or water pollution. An enzyme, you will remember, is atype of protein found in all living things that changes the rate ofchemical reactions.Summarize As you read thissection, highlight the mainpoint in each paragraph.Then, write a short paragraphsummarizing what you havelearned.Cancer: A Mistake in the Cell CycleScientists think that cancer is caused by changes to one or moreof the genes that produce the substances that help to control thecell cycle. A gene is a part of DNA that controls the productionof a protein.
Cancer occurs when something causes the damagedgenes to go into action. When that happens, cancerous cells formmasses of tissue called tumors. Tumors keep normal cells fromgetting needed nutrients. This causes damage to organs. Cancercells can spread throughout the body to other organs as well.1. What occurs when uncontrolled cell division takesplace?________________________________________________________________________What are the causes of cancer?Cancer is the second leading cause of death in the UnitedStates. Only heart disease leads to more deaths each year. Butthe causes of cancer are hard to pinpoint. This is because bothenvironmental and genetic factors play a part.
We do know thatmany environmental factors damage the genes that control theREADING ESSENTIALSChapter 887NameDateClassSection8.3Control of the Cell Cycle, continuedcell cycle. Environmental factors include cigarette smoke, air andwater pollution, and exposure to ultraviolet radiation from thesun. Cancer may also be caused by genetic factors such as viralinfections that damage the genes.How can cancer be prevented?2. Infer Which snack is morehealthful? (Circle yourchoice.)a. an appleb. a chocolate candy barA healthful lifestyle reduces the risk of cancer. Experts agreethat diets low in fat and high in fiber content can reduce the riskfor many kinds of cancer.
Fruits, vegetables, and grain productsare good food choices because they are low in fat and high infiber. Other healthful choices such as daily exercise and not usingtobacco also are known to lower the risk of cancer.◗ After You ReadMini Glossarycancer: uncontrolled cell division that may becaused by environmental factors and/orchanges in enzyme production in the cellcyclegene: segment of DNA that controls protein production and the cell cycle________________________________________________________________________________________________________________________________________________________________________2. Place the following events in the appropriate box based on the order in which they occur:Uncontrolled cell division occurs.Cancerous cells form tumors that deprive normal cells of nutrients.Cancer occurs.Environmental factors or viral infections damage genes.1.2.3.4.Visit the Glencoe Science Web site at science.glencoe.com to findyour biology book and learn more about control of the cell cycle.88Chapter 8READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.1.
Write a sentence using both of the terms in the Mini Glossary above.NameDateClassSection9.1 The Need for EnergySC.F.1.4.1 The student knows that the body processes involve specific biochemical reactions governed by biochemicalprinciples. Also covers SC.B.1.4.1, SC.G.1.4.3◗ Before You ReadThis section tells about the need our bodies have for energy. Think about the many ways your bodyuses energy. When do you need energy? Write a list of these times.
After you read this section, addany other times that you learned about.________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________◗ Read to LearnCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Cell EnergyWe need energy to live. In fact, all living organisms need energyto live.
Plants and other green organisms are able to make energyfrom sunlight and store it to use later. Some organisms, like animals, cannot make their own energy. They must eat other organisms to get the energy they need.Many of the things our bodies do, called cell processes, needenergy. Some cell processes are muscles contracting during exercise, your heart pumping, and cell division. Your brain also needsenergy to do its work.Create a Quiz After youhave read this section, createa five-question quiz based onwhat you have learned.
Afteryou have written the questions, be sure to answer them.How do our cells get energy?After exercising, your body needs a quick source of energy.Perhaps you eat a granola bar to satisfy the need. The cells in ourbodies often need a quick source of energy. There is a molecule inyour cells called adenosine triphosphate (uh DEH nuh seen •tri FAHS fayt), or ATP for short which provides quick energy forcells when they need it.1. What does ATP do?________________________________________________________________________Forming and Breaking Down ATPATP has an adenosine molecule, a ribose sugar, and three phosphate groups held together by chemical bonds.
When one of thechemical bonds is broken, one of the phosphate groups is released.Energy is also released. This quick release of energy is then available for a cell to use.READING ESSENTIALSChapter 989NameDateClassSection9.1The Need for Energy, continuedATPAdenosinePPPPProteinAdenosine (ATP)+ EnergyADPPADPPAdenosineP+ EnergyPAdenosine diphosphate (ADP)energy it becomes ADP. ADP can then addanother phosphate group and become ATP.This cycle is repeated.B A protein binds to ATP and breaks thechemical bond, releasing energy and aphosphate group.
ATP becomes ADP andis released from the protein. The energyis used by the cell. This cycle is repeated.When one of the phosphate groups is released, ATP becomesadenosine diphosphate, or ADP. ADP has only two phosphategroups. ADP can add another phosphate group and become ATPagain.
The cycle of the formation and breakdown of ATP createsa source of energy. The figure above shows the cycle of ATP.How do cells get the energy they need from ATP?Many proteins have a special place where ATP can bind itself.When ATP releases its energy by breaking the phosphate bond,the cell uses the energy. After releasing the energy, ATP becomesADP and is released from the protein.
As you have learned, at thispoint ADP can bind with another phosphate group and form ATPagain. This cycle is repeated, providing a renewable source ofenergy for the cell.Uses of Cell Energy2. Analyze A cell’s internalenvironment is kept stable through (Circle yourchoice.)a. ATP.b. homeostasis.c. ADP.90Chapter 9Cells use the energy they receive from ATP in many ways.Some cells make new molecules with the energy.
Other cells usethe energy to build membranes and cell organelles. Some cellsuse energy to maintain homeostasis, which is the regulation oftheir internal environment. Kidneys use energy to eliminatewastes from the bloodstream. At the same time the kidneys areeliminating wastes, they are using energy to keep needed substances in the bloodstream.READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.A When ATP releases a phosphate group andNameDateClassSection9.1The Need for Energy, continued◗ After You ReadMini GlossaryADP (adenosine diphosphate): molecule formedfrom the releasing of a phosphate groupfrom ATP; results in a release of energy thatis used for biological reactionsATP (adenosine triphosphate): energy-storingmolecule in cells composed of an adenosine molecule, a ribose sugar, and threephosphate groups; energy is stored in themolecule’s chemical bonds and can be usedquickly and easily by cells1.
On the lines below, tell how the two terms in the Mini Glossary above are related.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________2. Use the diagram to help you review what you have read. Fill in the boxes to show the complete formation and breakdown cycle of ATP.Copyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.ATPmoleculeADPmolecule3. Fill in the missing number in the statements that describe the formation and breakdownof ATP.ATP contains____________phosphategroup(s).____________phosphategroup(s) isreleased.ADP contains____________phosphategroup(s).ADP adds____________phosphategroup(s) tobecome ATP.Visit the Glencoe Science Web site at science.glencoe.com to findyour biology book and learn more about the need for energy.READING ESSENTIALSChapter 991NameDateClassSection9.2 Photosynthesis:Trapping the Sun’s Energy◗ Before You ReadSC.B.1.4.1 The student understands how knowledge of energy is fundamental to all scientific disciplines (e.g., for biological processes in living organisms and energy required forbuilding, erosion, and rebuilding of the Earth).
Also covers SC.F.1.4.3, SC.G.1.4.3This section tells how plants trap sunlight to make energy. The process, called photosynthesis, isone of the key terms for this section. Highlight each of the key terms in the Read to Learn section.Then use a different color to highlight the definition of each key term.◗ Read to LearnMake Flash Cards For eachparagraph, think of a question that might be on a test.Write the question on oneside of a flash card.
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