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Learn about the key classes of macromolecules, including carbohydrates, lipids, proteins, and nucleic acids. Understand their structure, function, and how polymers are built. Discover the role of monosaccharides, disaccharides, and polysaccharides. Explore the diversity of lipids and the importance of proteins in cellular functions. Dive into the informational role of nucleic acids in heredity.
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CH. 5 THE STRUCTURE AND FUNCTION OF MACROMOLECULES
Figure 5.1 Building models to study the structure and function of macromolecules
I. Polymer Principles • A. Most macromolecules are polymers • FOUR MAJOR CLASSES: CARBOHYDRATES, LIPIDS, PROTEINS, AND NUCLEIC ACIDS • MACROMOLECULES: A GIANT MOLECULE OF LIVING MATTER FORMED BY THE JIOINING OF SMALLER MOLECULES • POLYMERS: CHAINS OF IDENTICAL OR SIMILAR BUILDING BLOCKS CALLED MONOMERS • MONOMERS: THE SUBUNIT THAT SERVES AS THE BUILDING BLOCK OF A POLYMER
B. A limitless variety of polymers can be built from a small set of monomers • EACH CLASS OF POLYMER IS FORMED FROM A SPECIFIC SET OF MONOMERS
II. Carbohydrates: Fuel and Building Material • A. Sugars, the smallest carbohydrates, serve as fuel and carbon sources • MONOSACCHARIDES ARE THE SIMPLEST CARBOHYDRATES • USES • DIRECTLY FOR FUEL • CONVERTED TO OTHER TYPES OF ORGANIC MOLECULES • MONOMERS FOR POLYMERS
Figure 5.3 The structure and classification of some monosaccharides
DISSACHARIDES CONSITST OF TWO MONOSACCHARIDES CONNECTED BY GLYSODIC LINKAGE • GLYCOSIDIC LINKAGE: A COVALENT BOND FORMED BETWEEN TWO MONOSACCHARIDES BY A DEHYDRATION REACTION • DEHYDRATION REACTION: REMOVAL OF WATER
Figure 5.5x Glucose monomer and disaccharides Glucose monomer Sucrose Maltose
B. Polysaccharides, the polymers of sugars, have storage and structural roles • THE MONOSACCHARIDE MONOMERS OF POLYSACCHARIDES ARE CONNECTED BY GLYCOSIDIC LINKAGES EX. STARCH (IN PLANTS) AND GLYCOGEN (IN ANIMALS) ARE STORAGE POLYMERS OF GLUCOSE EX. CELLULOSE IS A STRUCTURAL POLYMER OF GLUCOSE (IN PLANTS)
III. Lipids: Diverse Hydrophobic Molecules • INTRODUCTION: • LIPIDS ARE THE ONE CLASS OF LARGE BIOLOGICAL MOLECULES THAT DOES NOT INCLUDE POLYMERS. • THE COMPOUNDS CALLED LIPIDS ARE GROUPED TOGETHER BECAUSE THEY SHARE ONE IMPORTANT TRAIT: THEY HAVE LITTLE OR NO AFFINITY FOR WATER. • THE MOST IMPORTANT FAMILIES OF LIPIDS ARE THE FATS, PHOSPHOLIPIDS, AND STEROIDS. • A. Fats store large amounts of energy
A. Fats store large amounts of energy • FATS (TRIACYLGLYCEROLS) FORMED BY A GLYCEROL MOLECULE JOINED TO 3 FATTY ACIDS BY DEHYDRATION REACTIONS • SATURATED: HAVE MAX. NUMBER OF HYDROGEN ATOMS • UNSATURATED: HAVE ONE OR MORE DOUBLE BONDS BETWEEN THEIR CARBONS
FIGURE 5.10 THE SYNTHESIS AND STRUCTURE OF A FAT, OR TRIACYLGLYCEROL
Figure 5.11x Saturated and unsaturated fats and fatty acids: butter and oil
Figure 5.11 Examples of saturated and unsaturated fats and fatty acids
B. Phospholipids are major components of cell membranes • PHOSPHOLIPIDS HAVE A NEGATIVELY CHARGED PHOSPHATE GROUP • THE “HEAD” OF A PHOSPHOLIPID IS HYDROPHILIC • THE “TAIL” IS HYDROPHOBIC
C. Steroids include cholesterol and certain hormones • STEROIDS HAVE A BASIC STRUCTURE OF FOUR FUSED RINGS OF CARBON ATOMS • CHOLESTEROL IS A MOLECULE FROM WHICH OTHER STEROIDS, INCLUDING THE SEX HORMONES, ARE SYNTHESIZED. • STEROIDS VARY IN THE FUNCTIONAL GROUPS ATTACHED.
IV. Proteins: The Molecular Tools of the Cell • INTRODUCTION • A PROTEIN CONSISTS OF ONE OR MORE POLYPEPTIDE CHAINS FOLDED INTO A SPECIFIC 3-D CONFORMATION
A. Polypeptide is a polymer of amino acids connected in a specific sequence • A POLYPEPTIDE IS A POLYMER OF AMINO ACIDS CONNECTED IN A SPECIFIC SEQUENCE • PROTEINS ARE CONSTRUCTED FROM 20 DIFFERENT AMINO ACIDS • EACH AMINO ACID HAS A CHARACTERISTIC SIDE CHAIN (R-GROUP) • THE CARBOXYL AND AMINO GROUPS OF ADJACENT AMINO ACIDS LINK TOGETHER IN PEPTIDE BONDS
B. A protein’s function depends on its specific conformation • PRIMARY STRUCTURE: UNIQUE SEQUENCE OF AMINO ACIDS • SECONDARY STRUCTURE: FOLDING OR COILING OF THE POLYPEPTIDE INTO REPEATING CONFIGURATIONS • EX. ALPHA-HELIX OR PLEADED SHEET • TERTIARY STRUCTURE: OVERALL 3-D SHAPE OF A POLYPEPTIDE RESULTING FROM THE INTERACTIONS BETWEEN AMINO ACID SIDE CHAINS. • QUARTENARY STRUCTURE: PROTEINS MADE OF MORE THAN ONE POLYPEPTIDE CHAIN
V. Nucleic Acids: Informational Polymers • A. Nucleic acids store and transmit hereditary information • NUCLEIC ACIDS STORE AND TRANSMIT HEREDITARY INFORMATION • DNA STORES INFORMATION FOR THE SYNTHESIS OF SPECIFIC PROTEINS • RNA CARRIES THIS GENETIC INFORMATION TO THE PROTEIN SYNTHESIZING MACHINERY
B. A nucleic acid strand is a polymer of nucleotides • EACH NUCLEOTIDE MONOMER CONSISTS OF A SUGAR COVANTLY BONDED TO A PHOSPHATE GROUP AND TO ONE OF FOUR NITROGENOUS BASES (A,T,C,G) • RNA HAS RIBOSE AS ITS SUGAR, DNA HAS DEOXYRIBOSE • RNA DOES NOT HAVE THYMINE, INSTEAD URACIL AS A NITROGENOUS BASE
FIGURE 5.27 THE STRUCTURE OF NUCLEOTIDES AND POLYNEUCLOTIDES
C. Inheritance is based on replication of the DNA double helix • DNA IS A HELICAL, DOUBLE STRANDED MACROMOLECULE WITH BASES PROJECTING INTO THE INTERIOR OF THE MOLECULE • DNA STRANDS ARE COMPLEMENTARY (A=T, C=G) • ONE STRAND OF DNA CAN SERVE AS A TEMPLATE FOR THE FORMATION OF THE OTHER • DNA PROVIDES A MECHANISM FOR THE CONTINUITY OF LIFE