The Chemistry of Life: Organic Compounds The Chemistry of Life: Organic Compounds Chapter 3.
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Transcript of The Chemistry of Life: Organic Compounds The Chemistry of Life: Organic Compounds Chapter 3.
The Chemistry of Life:The Chemistry of Life:Organic CompoundsOrganic Compounds
Chapter 3
Learning Objective 1Learning Objective 1
• What properties make carbon the central component of organic compounds?
Carbon Atoms Carbon Atoms
• form four covalent bonds• single, double, or triple• straight or branched chains• rings
• bond with many different elements
Organic MoleculesOrganic Molecules
• Chains
Organic MoleculesOrganic Molecules
• Double bonds
Organic MoleculesOrganic Molecules
• Branched chains
Organic MoleculesOrganic Molecules
• Rings
KEY CONCEPTSKEY CONCEPTS
• Carbon atoms join with one another or other atoms to form large molecules with a wide variety of shapes
Learning Objective 2Learning Objective 2
• What is an isomer?
• What are the 3 principal isomer types?
IsomersIsomers
• Structural isomers• different covalent arrangements
IsomersIsomers
• Geometric isomers (cis–trans isomers)• different spatial arrangements
IsomersIsomers
• Enantiomers• mirror images
Learning Objective 3Learning Objective 3
• What are the major functional groups present in organic compounds, and their properties?
HydrocarbonsHydrocarbons
• Organic compounds• carbon and hydrogen only• nonpolar• hydrophobic
• Methyl group
Polar and Ionic Polar and Ionic Functional Groups Functional Groups
• Partial charges on atoms• at opposite ends of a bond• interact with one another• hydrophilic
• Hydroxyl and carbonyl groups
Acidic and Basic GroupsAcidic and Basic Groups
• Acidic• release hydrogen ions • become negatively charged• carboxyl and phosphate groups
• Basic• accepts a hydrogen ion• become positively charged• amino group
Functional GroupsFunctional Groups
• Polar (hydroxyl)
• Acidic (carboxyl)
• Basic (amino)
Table 3-1a, p. 49
Table 3-1b, p. 49
KEY CONCEPTSKEY CONCEPTS
• Hydrocarbons• nonpolar and hydrophobic
• Properties depend on functional groups: • hydroxyl and carbonyl groups (polar)• carboxyl and phosphate groups (acidic)• amino groups (basic)
Learning Objective 4Learning Objective 4
• What is the relationship between polymers and macromolecules?
Polymers and MacromoleculesPolymers and Macromolecules
• Polymers • long chains of monomers • linked through condensation reactions
• Macromolecules • large polymers• polysaccharides, proteins, and DNA• broken down by hydrolysis reactions
Condensation and HydrolysisCondensation and Hydrolysis
Fig. 3-5, p. 50
H2O
Condensation
Enzyme A
Hydrolysis
Enzyme BMonomerMonomer Dimer
HO OH HO OH HO O OH +
Learning Objective 5Learning Objective 5
• Distinguish among monosaccharides, disaccharides, and polysaccharides
• What is the difference between storage polysaccharides and structural polysaccharides?
CarbohydratesCarbohydrates
• Ratio• 1carbon: 2 hydrogen: 1 oxygen
• Monosaccharide• simple sugar• glucose, fructose, ribose
• Disaccharide• 2 monosaccharides• joined by glycosidic linkage • maltose, sucrose
Fig. 3-6, p. 51
Fig. 3-6, p. 51
Dihydroxyacetone (C3H6O3)(a ketone)
(a) Triose sugars (3-carbon sugars)
Glyceraldehyde (C3H6O3)(an aldehyde)
Fig. 3-6, p. 51
Ribose (C5H10O5)(the sugar component of RNA)
(b) Pentose sugars (5-carbon sugars)
Deoxyribose (C5H10O4)(the sugar component of DNA)
Fig. 3-6, p. 51
Glucose (C6H12O6)(an aldehyde)
(c) Hexose sugars (6-carbon sugars)
Galactose (C6H12O6)(an aldehyde)
Fructose (C6H12O6)(a ketone)
PolysaccharidesPolysaccharides
• Long chains• repeating units of simple sugar
• Storage polysaccharides• starch in plants • glycogen in animals
• Structural polysaccharide• cellulose, cell walls of plants
PolysaccharidesPolysaccharides
• Starch
KEY CONCEPTSKEY CONCEPTS
• Carbohydrates are composed of sugar subunits (monosaccharides), which can be joined to form disaccharides, storage polysaccharides, and structural polysaccharides
Learning Objective 6Learning Objective 6
• What are the characteristics, composition, and biological functions of fats, phospholipids, and steroids?
LipidsLipids
• Mainly hydrocarbon-containing regions• few oxygens (polar or ionic groups)
• Greasy or oily consistency• relatively insoluble in water
FatsFats
• Triacylglycerol• main storage fat• glycerol + 3 fatty acids
• Monoacylglycerols & diacylglycerols• 1 or 2 fatty acids
• saturated or unsaturated fatty acid• hydrogens
TriacylglycerolTriacylglycerol
Fig. 3-12b, p. 56
Ester linkage
A triacylglycerol
PhospholipidsPhospholipids
• Structure• glycerol • 2 fatty acids• phosphate group
• Function• cell membrane component
PhospholipidPhospholipid
Fig. 3-13, p. 58
Fatty acidsCholine
PhosphategroupGlycerol
Hydrophilichead
Hydrophobictail
Water
SteroidsSteroids
• Carbon atoms arranged in 4 rings • cholesterol, bile salts, some hormones
Fig. 3-15a, p. 59
Cholesterol
(a) Cholesterol is an essential component of animalcell membranes.
Indicatesdouble bond
KEY CONCEPTSKEY CONCEPTS
• Lipids store energy (triacylglycerol) and are the main structural components of cell membranes (phospholipids)
Learning Objective 7Learning Objective 7
• What are the structures and functions of proteins?
ProteinsProteins
• Polypeptides• long, linear polymers • 20 amino acids (monomers)• joined by peptide bonds
• Many functions• enzymes• structural components• cell regulators
Peptide BondsPeptide Bonds
Fig. 3-18, p. 63
Glycylalanine (a dipeptide)
R groupCarboxyl
groupAminogroup R group Peptide bond
Glycine Alanine
Learning Objective 8Learning Objective 8
• What features are shared by all amino acids?
• How are amino acids grouped into classes based on their side chains?
Amino AcidsAmino Acids
• Amino group and carboxyl group
• Side chains• determine chemical properties• nonpolar, polar, acidic, or basic
• Dipolar ions at cell pH• important biological buffers
Dipolar IonsDipolar Ions
Learning Objective 9Learning Objective 9
• What are the four levels of organization of protein molecules?
Primary StructurePrimary Structure
• Linear sequence of amino acids in polypeptide chain
Secondary StructureSecondary Structure
• Regular conformation• α-helix or β-pleated sheet• hydrogen bonds between amino acids
Fig. 3-20a, p. 64
(a) In an α-helix the R groups project out from the sides. (TheR groups have been omitted in the simplified diagram at left.)
Hydrogen bondshold helix coilsin shape
KEY:
Carbon atom
Oxygen atom
Nitrogen atom
Hydrogen atom
R group
Tertiary StructureTertiary Structure
• Overall shape of polypeptide chain• chemical interactions of side chains
Fig. 3-21a, p. 65
Hydrophobicinteraction
Hydrogenbond
Ionic bond
Disulfide bond
(a) Hydrogen bonds, ionic bonds, hydrophobic interactions,and disulfide bridges between R groups hold the parts ofthe molecule in the designated shape.
Quaternary StructureQuaternary Structure
• 2 or more polypeptide chains
Fig. 3-22a, p. 66
Alpha chain(α-globin)
Heme Alpha chain(α-globin)
Beta chain(β-globin)
(a) Hemoglobin, a globular protein, consistsof four polypeptide chains, each joined to aniron-containing molecule, a heme.
Beta chain(β-globin)
Alpha chain(α-globin)
Alpha chain(α-globin)
Stepped Art
Fig. 3-22a, p. 66
Heme
Beta chain(β-globin)
Beta chain(β-globin)
KEY CONCEPTSKEY CONCEPTS
• Proteins have multiple levels of structure and are composed of amino acid subunits joined by peptide bonds
Learning Objective 10Learning Objective 10
• What are the components of a nucleotide?
• Name some nucleic acids and nucleotides, and discuss their importance in living organisms
NucleotidesNucleotides
• Nitrogenous base• 2-ring purine or 1-ring pyrimidine
• Five-carbon sugar• ribose or deoxyribose
• One or more phosphate groups
Purines and PyrimidinesPurines and Pyrimidines
Fig. 3-23a, p. 68
(a) Pyrimidines. The three major pyrimidine bases found innucleotides are cytosine, thymine (in DNA only), and uracil(in RNA only).
Cytosine (C) Uracil (U)Thymine (T)
Fig. 3-23b, p. 68
(b) Purines. The two major purine bases found in nucleotidesare adenine and guanine.
Adenine (A) Guanine (G)
Nucleic AcidsNucleic Acids
• DNA and RNA• long chains of nucleotides
• Store and transfer information• sequence of amino acids in proteins• structure and function of the organism
Nucleic AcidNucleic Acid
• RNA
Fig. 3-24, p. 68
Phosphodiesterlinkage
Nucleotide
Guanine
Uracil
Adenine
Cytosine
Ribose
Ribose
Ribose
Ribose
NucleotidesNucleotides
• ATP (adenosine triphosphate)• essential in energy metabolism
• NAD+ • electron acceptor in biological oxidation
and reduction reactions
NucleotidesNucleotides
• cAMP
KEY CONCEPTSKEY CONCEPTS
• Nucleic acids (DNA and RNA) are informational molecules composed of long chains of nucleotide subunits. ATP and some other nucleotides have a central role in energy metabolism
Learning Objective 11Learning Objective 11
• Review the functions and chemical compositions of the 4 major groups of organic compounds: carbohydrates, lipids, proteins, and nucleic acids
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Structure of a PhospholipidStructure of a Phospholipid
Condensation and HydrolysisCondensation and Hydrolysis
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Secondary and Tertiary Secondary and Tertiary StructureStructure
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Structure of Starch and Structure of Starch and CelluloseCellulose
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Triglyceride FormationTriglyceride Formation
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