Understanding Cells - Teamsmithgreene1.weebly

Cell Structure and FunctionCells and LifeKey ConceptsWhat do you think? Read the two statements below and decidewhether you agree or disagree with them. Place an A in the Beforecolumn if you agree with the statement or a D if you disagree. Afteryou’ve read this lesson, reread the statements to see if you have changedyour mind.BeforeStatement How did scientists’understanding of cellsdevelop? What basic substancesmake up a cell?After1. Nonliving things have cells.2. Cells are made mostly of water.Copyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Understanding CellsThe cells that make up all living things are very small.Early scientists did not have the tools to see cells until theinvention of the microscope. More than 300 years ago,Robert Hooke built a microscope. He used it to look at cork.He saw small openings in the cork similar to the honeycombshown in the figure below. The openings reminded him ofthe small rooms, called cells, where monks lived. Hookenamed these small structures cells.Identify Main Ideas As youread, highlight the mainideas under each heading.After you finish reading,review the main ideas of thelesson.Visual Check1. Identify The smallopenings of the honeycomblook most like which of thefollowing? (Circle the correctanswer.)a. cellsb. plantsc. tiny animalsReading EssentialsCell Structure and Function17

The Cell Theory2. Define What are thethree principles of the celltheory?Scientists made better microscopes. They looked for cellsin places such as pond water and blood. The newermicroscopes made it possible for scientists to see differentstructures inside cells. A scientist named Matthias Schleiden(SHLI dun) looked at plant cells. Another scientist, TheodoreSchwann, studied animal cells. Later, Rudolf Virchow (VURkoh) said all cells come from cells that already exist. Theobservations made by these scientists, shown in the tablebelow, became known as the cell theory. The cell theory statesthat all living things are made of one or more cells, cells are the smallestunit of life, and all new cells come from cells that already exist.Cell Theory MatchupKey Concept Check3. Explain how scientists’Scientista. By studying plants, hedetermined that all living thingsare made of one or more cells.2. Rudolf Virchowb. By studying animals, hedetermined that all living thingsare made of one or more cells.3. Matthias Schleidenc. All new cells come from cellsthat already exist.Visual CheckBasic Cell SubstancesReading Check5. Define What aremacromolecules?18Cell Structure and FunctionThe cell theory raised more questions for scientists.Scientists began to look into what cells are made of. Cells aremade of smaller parts called macromolecules that form when manysmall molecules join together.Reading EssentialsCopyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.1. Theodore Schwannunderstanding of cellsdeveloped.4. Identify Match thescientist with his part ofthe cell theory. Draw a linefrom the scientist to hisobservation.Observation

The Main Ingredient—WaterThe main ingredient in every cell is water. Water makesup more than 75 percent of a cell. It is necessary for life.Water also surrounds cells. The water surrounding your cellshelps to insulate your body. This helps your body maintain astable internal environment, or homeostasis.Water also is useful because it can dissolve othersubstances, such as salt (sodium chloride). For substances tomove into and out of a cell, they must be dissolved in aliquid. In the figure below, the water molecules have apositive end and a negative end. The more negative end of a water molecule (-) canattract the positive part of another substance. The more positive end of a water molecule ( ) canattract the negative part of another substance. Withsodium chloride, the sodium (Na) ions and chloride(Cl) ions are more attracted by the water molecules.This attraction is similar to the attraction of magnets.6. Compare How is theattraction of water moleculessimilar to the attraction ofmagnets?WaterCopyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. C I]NaáSodiumChlorideVisual Check7. Identify Which part ofthe salt crystal is attractedto the oxygen in the watermolecule?Water C I] Reading Essentials 1 Naá Cell Structure and Function19

MacromoleculesMake a four-page book toorganize information aboutmacromolecules in a cell.NucleicacidsProteinsLipidsCarbohydratesAll cells contain other substances besides water that helpcells do what they do. There are four types ofmacromolecules in cells. They are nucleic acids, proteins,lipids, and carbohydrates. Each type of macromolecule hasits own job, or function, in a cell. These functions rangefrom growth and communication to movement and storage.The table below describes each macromolecule’s function.Macromolecules in CellsNucleicAcidsElementsVisual Check8. Identify twomacromolecules whosefunction is to providesupport to a s ir (horns,feathers)fatsoilssugarsstarchcellulose store largeamounts ofenergy formboundariesaroundcells supply energyfor cellprocesses short-termenergystorage providestructuralsupport carry regulatehereditarycellinformationprocesses used to providemakestructuralproteinssupportNucleic Acids Both deoxyribonucleic (dee AHK sih ri bohnoo klee ihk) acid (DNA) and ribonucleic (ri boh noo KLEEihk) acid (RNA) are nucleic acids. Nucleic acids aremacromolecules formed when long chains of molecules callednucleotides (NEW klee uh tidz) join together. Nucleic acids areimportant because they contain the genetic material of acell. This information is passed from parents to offspring.Reading Check9. Name three instructionsthat DNA provides to a cell.DNA includes instructions for cell growth, for cellreproduction, and for cell processes that enable a cell torespond to its environment. DNA is used to make RNA. RNAis used to make proteins.The order of nucleotides in DNA and RNA is important.A change in the order of the nucleotides can change theinformation in a cell.20Cell Structure and FunctionReading EssentialsCopyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.carbonoxygenhydrogennitrogensulfur

Proteins The macromolecules necessary for almosteverything cells do are proteins. A protein is a macromoleculemade of long chains of amino acid molecules. RNA containsinstructions for joining amino acids together.Cells have hundreds of proteins. Each protein has its ownfunction. Some proteins help cells communicate with othercells. Other proteins move substances around inside cells.Some proteins help to break down nutrients in food. Otherproteins, such as keratin (KER uh tun), which is found inhair, horns, and feathers, make up supporting structures.Lipids A lipid is a large macromolecule that does not dissolve inwater. Because lipids do not dissolve in water, they protectcells. Lipids also are a large part of the cell membrane. Lipidsstore energy for cells and help with cell communication.Cholesterol (kuh LES tuh rawl), phospholipids (fahs foh LIHpids), and vitamin A are lipids.Carbohydrates One sugar molecule, two sugar molecules, or a longCopyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.chain of sugar molecules make up carbohydrates (kar boh HI drayts).Carbohydrates store energy, provide structural support forcells, and help cells communicate. Sugars and starches arecarbohydrates that store energy. Fruits contain sugars. Breadand pasta are mostly starch. The energy stored in sugars andstarches can be released quickly through chemical reactionsin cells. Cellulose is a carbohydrate in the cell walls of plantsthat provides support.Reading Check10. Identify threefunctions of proteinsin cells.Reading Check11. Explain Why are lipidsimportant to cells?Key Concept Check12. Name the basicsubstances that makeup a cell.Reading EssentialsCell Structure and Function21

Mini Glossarycarbohydrate: (kar boh HI drayt): one sugar molecule,two sugar molecules, or a long chain of sugar moleculescell theory: states that all living things are made of one ormore cells, the cell is the smallest unit of life, and all newcells come from preexisting cellsmacromolecule: a substance that forms by joining manysmall molecules togethernucleic acid: a macromolecule that forms when long chains ofmolecules called nucleotides join togetherprotein: a long chain of amino acid moleculeslipid: a large macromolecule that does not dissolve in water1. Review the terms and their definitions in the Mini Glossary. Write a sentence thatdescribes a lipid.2. Fill in the chart below by identifying the different types of macromolecules and givingexamples of each.Macromoleculesnucleic acidsDNA and RNACopyright Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.3. How did highlighting the main ideas in each section of this lesson improve yourunderstanding of the cell?What do you thinkReread the statements at the beginning of thelesson. Fill in the After column with an A if youagree with the statement or a D if you disagree.Did you change your mind?22Cell Structure and FunctionConnect EDLog on to ConnectED.mcgraw-hill.comand access your textbook to find thislesson’s resources.END OFLESSONReading Essentials

koh) said all cells come from cells that already exist. The observations made by these scientists, shown in the table below, became known as the cell theory. The cell theory states that all living things are made of one or more cells, cells are the smallest unit of life, and all new cells come from