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Ch 2 Notes. Molecules of Life. Four categories of molecules are unique to cells (called macromolecules ) Carbohydrates Lipids Proteins Nucleic acids Synthesis of macromolecules involves a dehydration reaction Breakdown of macromolecules involves a hydrolysis reaction. Carbohydrates. - PowerPoint PPT Presentation


Ch 2 Notes

Ch 2 NotesMolecules of LifeFour categories of molecules are unique to cells (called macromolecules)CarbohydratesLipidsProteinsNucleic acidsSynthesis of macromolecules involves a dehydration reactionBreakdown of macromolecules involves a hydrolysis reactionCarbohydratesThe ratio of hydrogen (H) atoms to oxygen (O) atoms is approximately 2:1Function for quick, short-term cellular energy

CarbohydratesSimple carbohydratesLow number of carbon atoms (3-7)MonosaccharidesGlucose Fructose found in fruitsGalactose found in milkDisaccharidesTwo monosaccharides joined togetherSucrose (table sugar) formed when glucose joins with fructoseLactose formed when glucose joins with galactose

CarbohydratesComplex carbohydratesContain many glucose (monosaccharide) unitsStarch storage form of glucose in plantsGlycogen storage form of glucose in animalsCelluloseFound in plant cell wallsHumans are unable to digest (passes through digestive tract as fiber)LipidsContain more energy per gram than other biological moleculesSome function as long-term energy storage in organismsDo not dissolve in water Consist mostly of carbon and hydrogen atoms; contain few oxygen atoms

LipidsFats and OilsFormed when one glycerol molecule reacts with three fatty acid moleculesFatsUsually of animal originSolid at room temperatureUsed for long-term energy storage, insulation, and cushioningOilsUsually of plant originLiquid at room temperatureLipidsEmulsification cause fats to mix with waterSaturated and Unsaturated Fatty AcidsFatty acid (carbon-hydrogen chain ending with an acidic group COOHSaturated fatty acids have only single covalent bonds; lard and butter are examplesUnsaturated fatty acids have double bonds between carbon atoms wherever fewer than two hydrogens are bonded to a carbon atom; vegetable oilsLipidsSteroidsStructure consists of four fused carbon rings with attached functional groupsCholesterolStructural component of animal cell membranePrecursor of several other steroids

ProteinsFunction of proteinsFibrous structural proteinsHormonesMuscle contractionTransportProtectionEnzymesProteinsStructure of proteinsMade of amino acid subunitsAmino groupAcid groupR (Remainder) group differentiates amino acidsDipeptide two amino acids joined togetherPolypeptide three or more amino acids joined together

Nucleic AcidsHuge macromolecules composed of nucleotidesNucleotides composed of 3 subunit molecules:A phosphateA pentose sugarA nitrogen-containing baseTwo classes of nucleic acidsDNARNA

Nucleic AcidsTwo classes of nucleic acidsDNAMake up genesContain pentose sugar deoxyriboseNitrogen-containing basesAdenine (A)Thymine (T)Guanine (G)Cytosine (C)Usually double stranded

Nucleic AcidsRNAIntermediary in process of protein synthesisContain pentose sugar riboseThe nitrogen-containing base uracil (U) replaces thymineUsually single stranded