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Exploring LifeExploring Life

Chapter 4+ 5 Study GuideChapter 4+ 5 Study Guide

4.1 Life Requires about 25 chemical 4.1 Life Requires about 25 chemical elementselements

4.2 Skip4.2 Skip

4.3 skip4.3 skip

4.4 Life Depends on the unique 4.4 Life Depends on the unique properties of waterproperties of water

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4.1 Life Requires 4.1 Life Requires about 25 chemical about 25 chemical elementselements Why is there chemistry in a Why is there chemistry in a

biology textbook? biology textbook? The answer is that all of biology The answer is that all of biology

involves chemistry.involves chemistry. All living things All living things shareshare the same the same

chemical building blockschemical building blocks and and depend depend on chemical processes for on chemical processes for survival.survival.

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4.1 Life Requires 4.1 Life Requires about 25 chemical about 25 chemical elementselements

Elements- About Elements- About 2525 elements elements

are essential to are essential to lifelife . . of these elementsof these elements

oxygen oxygen (O), (O), carbon carbon (C),(C),

hydrogenhydrogen (H), (H),

and and nitrogennitrogen (N)— (N)—

make up about make up about

96 percent96 percent of your body. of your body.

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4.4 Life Depends on the 4.4 Life Depends on the unique properties of waterunique properties of water

•All living things are All living things are dependent on water.dependent on water.

• Inside your body, your cells Inside your body, your cells are surrounded by a fluid are surrounded by a fluid that is mostly water, and that is mostly water, and your your cellscells themselves are 70 themselves are 70 to 95 percent waterto 95 percent water

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4.4 Life Depends on the unique properties of 4.4 Life Depends on the unique properties of waterwater

• The tendency of molecules of the The tendency of molecules of the same kind to stick to one another is same kind to stick to one another is called called cohesioncohesion. .

• Cohesion is much stronger for water Cohesion is much stronger for water than for most other liquids. than for most other liquids.

• Water molecules are Water molecules are

also attracted toalso attracted to

certain other molecules.certain other molecules.

This is called This is called adhesionadhesion

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4.4 Life Depends on the unique 4.4 Life Depends on the unique properties of waterproperties of water

• Trees depend on Trees depend on

cohesion and adhesioncohesion and adhesion

to help transport water to help transport water

from their roots to from their roots to

their leaves their leaves • This effect is known This effect is known

as as surface tensionsurface tension. .

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4.4 Life Depends on the unique 4.4 Life Depends on the unique properties of waterproperties of water

•You've witnessed another You've witnessed another example ofexample of cohesion cohesion if you've if you've ever seen an ever seen an insect "skatinginsect "skating" " across the surface of a pond. across the surface of a pond.

•This This effect is an example effect is an example of of surface tension,surface tension, alsoalso

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4.4 Life Depends on the unique 4.4 Life Depends on the unique properties of waterproperties of water

• Temperature ModerationTemperature Moderation

If you have ever burned your finger If you have ever burned your finger on a metal pot while waiting for on a metal pot while waiting for the water in it to boil, you know the water in it to boil, you know that water heats up much more that water heats up much more slowly than metal.slowly than metal.

In fact, because of hydrogen bonding, In fact, because of hydrogen bonding, water water has a better ability tohas a better ability to resist temperature changeresist temperature change than most other substances than most other substances

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4.4 Life Depends on the unique 4.4 Life Depends on the unique properties of waterproperties of water

• One result of this property (temperature One result of this property (temperature moderation) is that it causes moderation) is that it causes oceans and oceans and large lakeslarge lakes to to moderatemoderate the the temperatures temperatures of nearby land areas of nearby land areas

• Water also moderatesWater also moderates• temperature through temperature through evaporationevaporation, , • such as when you sweat.such as when you sweat.

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4.4 Life Depends on the unique 4.4 Life Depends on the unique properties of waterproperties of water

• Ice floatsIce floats because its molecules are because its molecules are less densely packed than those in less densely packed than those in liquid water. liquid water.

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• How is the fact that ice floats important to How is the fact that ice floats important to living things? living things?

• If ice sank, it would form on the bottom of a If ice sank, it would form on the bottom of a body of water as the water was cooling.body of water as the water was cooling.

• Ponds and lakes would freeze from the Ponds and lakes would freeze from the bottom up, trapping the fish and other bottom up, trapping the fish and other organisms in a shrinking layer of water organisms in a shrinking layer of water without access to the nutrients from the without access to the nutrients from the muddy bottom.muddy bottom.

• Instead, when a deep body of water cools, Instead, when a deep body of water cools, • the floating ice insulates the liquid water the floating ice insulates the liquid water

below, allowing life to persist under the below, allowing life to persist under the frozen surface.frozen surface.

4.4 Life Depends on the unique properties of 4.4 Life Depends on the unique properties of waterwater

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4.4 Life Depends on the unique properties of 4.4 Life Depends on the unique properties of waterwater

• WaterWater is the main is the main solventsolvent inside all inside all cellscells, ,

• in blood, in blood,

• and in plant sap. and in plant sap.

• Water dissolves an enormous variety Water dissolves an enormous variety of solutes necessary for life. of solutes necessary for life.

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4.4 Life Depends on the unique 4.4 Life Depends on the unique properties of waterproperties of water

• Acids, Bases, and pHAcids, Bases, and pHpH of 7 is neitherpH of 7 is neither acidic nor basic. acidic nor basic. The pH of the The pH of the solution insidesolution inside most living cellsmost living cells is close to 7.is close to 7. Which is the most acidic?Which is the most acidic?Which is the most basic?Which is the most basic?

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4.4 Life Depends on the unique 4.4 Life Depends on the unique properties of waterproperties of water• BuffersBuffers

• Because the molecules in cells are Because the molecules in cells are very sensitive to concentrations of very sensitive to concentrations of H+ and OH- ions, even a slight H+ and OH- ions, even a slight change in pH can be harmful to change in pH can be harmful to organisms. organisms.

• Many biological fluids contain Many biological fluids contain buffersbuffers, substances that cause a , substances that cause a solution to resist changes in pHsolution to resist changes in pH. .

• Blood contains buffers Blood contains buffers (like a sponge or (like a sponge or

barrier)barrier) so cells stay at pH 7.4 so cells stay at pH 7.4

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4.4 Life Depends on the unique 4.4 Life Depends on the unique properties of waterproperties of water

• Earth is perfect planet for LifeEarth is perfect planet for Life• Contains Contains waterwater• Just Just farfar enough and enough and close close enough to enough to

sunsun• Just enough energy and heatJust enough energy and heat• Ozone shields harmful radiationOzone shields harmful radiation

• Essential elements in rock, soil, airEssential elements in rock, soil, air• H, O, C are recycledH, O, C are recycled

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Chapter 5Chapter 5

5.1 Organic compounds5.1 Organic compounds 5.2 Carbohydrates5.2 Carbohydrates 5.3 Lipids5.3 Lipids 5.4 Proteins5.4 Proteins 5.5 Enzymes5.5 Enzymes

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5.1 Organic Compounds5.1 Organic Compounds

Carbon Carbon Carbon can form bonds with one or more other Carbon can form bonds with one or more other

carbon atoms, producing an endless variety of carbon atoms, producing an endless variety of carbon skeletons.carbon skeletons.

Most carbon-based molecules are classified as Most carbon-based molecules are classified as organic molecules organic molecules

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Building Organic CompoundsBuilding Organic Compounds

To build compoundsTo build compounds

A water molecule A water molecule

isis released released

This is called This is called

a a dehydration reactiondehydration reaction

because it involves because it involves

removing (removing (dede-)-) water (water (hydrohydro-).-).

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Breaking Down CompoundsBreaking Down Compounds

In a Hydrolysis reaction,In a Hydrolysis reaction,

water (water (hydrohydro-) is used -) is used

to break down to break down

(-(-lysislysis) compounds. ) compounds.

To summarize, water is removed to build a To summarize, water is removed to build a compound, and water is added to break it down. compound, and water is added to break it down.

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5.2 Carbohydrates5.2 CarbohydratesA A carbohydratecarbohydrate is an organic is an organic compound made up of sugar compound made up of sugar molecules.molecules. Sugars contain the elements Sugars contain the elements carbon, carbon,

hydrogenhydrogen, and , and oxygenoxygen in the ratio of in the ratio of 11 carbon: carbon: 22 hydrogen: hydrogen: 11 oxygen (CH2O) oxygen (CH2O)

MonosaccharidesMonosaccharides –simple sugar –simple sugar(Glucose, fructose, and galactose(Glucose, fructose, and galactose ) )DisaccharidesDisaccharides -2 sugars (sucrose) -2 sugars (sucrose) Polysaccharides-Polysaccharides--chain of sugars -chain of sugars

(Glycogen, cellulose, and starch )(Glycogen, cellulose, and starch )

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5.3 Lipids5.3 Lipids Oil's inability to mix with water is Oil's inability to mix with water is

typical of the class of water-avoiding typical of the class of water-avoiding compounds called compounds called lipidslipids

A A fatfat consists of a three-carbon consists of a three-carbon backbonebackbone

saturated fatsaturated fat

uunsaturated fatnsaturated fat

Steroids-hormones and cholesterolSteroids-hormones and cholesterol

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5.4 Proteins5.4 Proteins

A A proteinprotein is a polymer constructed from is a polymer constructed from a set of just 20 kinds of amino acidsa set of just 20 kinds of amino acids

Made up of C, H, O, N-Put this in your Made up of C, H, O, N-Put this in your notesnotes

Cells create proteins by linking amino Cells create proteins by linking amino acids together into acids together into

a chain called a a chain called a polypeptidepolypeptide

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5.5 Enzymes• To start a chemical reaction, it is first

necessary to weaken chemical bonds. This activation process requires that the molecules absorb energy. This "start-up" energy is called activation energy

• The main catalysts of chemical reactions in organisms

are specialized proteins called enzymes

• Enzymes provide a way for reactions to occur at the cell's normal temperature

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The enzyme sucrase,

which catalyzes

the hydrolysis (breakdown)

of sucrose (the substrate).

pH and temperature can affect how an enzyme works or if it can work at all

Enzymes are specific Enzymes can be re-used

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Organic compound and

Function ChartFunctions

Structural Enzymatic Storage

Organic Compound Energy Material Information

Carbohydrate X X xLipids X x xProteins x x x XNucleic Acids x

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• Video (Chemistry of Life 18 min)