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The Structure and Function of Macromolecules

  • Macromolecules

    • Are large molecules composed of smaller molecules

    • Are complex in their structure

    • Most macromolecules are polymers, built from monomers

    • Four classes of life’s organic molecules are polymers

      • Carbohydrates

      • Proteins

      • Nucleic acids

      • Lipids

    • A polymer

      • A long molecule consisting of many similar building blocks called monomers

      • Specific monomers make up each macromolecule

        • E.g. amino acids are the monomers for proteins

  • The Synthesis and Breakdown of Polymers

    • Monomers form larger molecules by condensation reaction called dehydration synthesis

    • Polymers and disassemble by hydrolysis

      • Addition of water molecules

    • Although organisms share the same limited number of monomer types, each organism is unique based on the arrangement of monomers into polymers

    • An immense variety of polymers can be built from a small set of monomers

  • Carbohydrates

    • Serve as fuel and building material

    • Include both sugars and polymers

      • Starch, cellulose, etc.

  • Sugars

    • Monosaccharides

      • Are the simplest sugars

      • Can be used for fuel

      • Can be converted into other organic molecules

      • Can be combined into polymers

      • Can be linear

      • Can form rings

    • Disaccharides

      • Consist of two monosaccharides

      • Are joined by a glycosidic linkage

    • Polysaccharides

      • Are polymers of sugars

      • Serve many roles in organism

    • Storage Polysaccharides

      • Starch

        • Is a polymer consisting entirely of glucose monomers

        • Is the major storage form of glucose in plants

      • Glycogen

        • Consists of glucose monomers

        • Is the major storage form of glucose in animals

      • Cellulose

        • Is a polymer of glucose

        • Has different glycosidic linkages than starch

        • Difficult to digest

          • Cows have microbes in their stomach to facilitate this process

      • Chitin

        • Is found in the exoskeleton of arthropods

        • Can be used as surgical thread

  • Lipids

    • Are the one class of large biological monomers that do not consist of polymers

    • Share the common trait of being hydrophobic

  • Fats

    • Constructed from two types of smaller molecules

      • A single glycerol and usually three fatty acids

    • Vary in length and number and location of double bonds they contain

    • Saturated fatty acids

      • Have the maximum number of hydrogen atoms possible

      • Have no double bonds

    • Unsaturated fatty acids

      • Have one or more double bonds

    • Phospholipids

      • Have only two fatty acids

      • Have a phosphate group instead of third fatty acid

      • Structure

        • Consists of a hydrophobic “head” and hydrophobic “tails”

        • Results in a bilayer arrangement founds in cell membranes

  • Steroids

    • Lipids characterized by a carbon skeleton consisting of four fused rings

    • Cholesterol

      • Found in cell membranes

      • Is a precursor for some hormones

  • Proteins

    • Proteins have many structures, resulting in a wide range of functions

    • Proteins do most of the work in cells and acts as enzymes

    • Proteins are made of monomers called amino acids

    • Enzyme

      • Type of protein that acts as a catalyst, speeding up chemical reactions

    • Polypeptides

      • Polymers of amino acids

      • A protein consists of one or more polypeptides

    • Amino acids

      • Are organic molecules possessing both carboxyl and amino groups

      • Differ in their properties due to differing side chains, called R groups

      • Linked by peptide bonds

  • Protein Conformation and Function

    • A protein’s specific conformation (shape) determines how it functions

  • Four Levels of Protein Structure

    • Primary structure

      • Unique sequence of amino acids in a polypeptide

    • Secondary structure

      • Folding or coiling of the polypeptide into a repeating configuration

      • Includes the a helix and β pleated sheet

    • Tertiary Structure

      • Overall three-dimensional shape of a polypeptide

      • Results from interactions between amino acids and R groups

    • Quaternary structure

      • The overall protein structure that results from the aggregation of two or more polypeptide subunits

  • Sickle Cell Disease

    • Results from a single amino acid substitution in the protein hemoglobin

  • What determines Protein Conformation

    • Protein conformation depends on the physical and chemical conditions of the protein’s environment

      • Temperature, pH, etc.

    • Denaturation is when a protein unravels and loses its native conformation

  • The Protein Folding Problem

    • Most proteins

      • Probably go through several intermediate states on their way to a stable conformation

      • Denaturated proteins no longer work in their unfolded conditions

      • Proteins may be denaturated by extreme changes in pH or temperature

    • Chaperonins

      • Protein molecules that assist in the proper folding of other proteins

    • X-ray crystallography

      • Used to determine a protein’s three-dimensional structure

  • Nucleic Acids

    • Store and transmit hereditary information

    • Genes

      • Are the units of inheritance

      • Program the amino acid sequence of polypeptides

      • Are made of nucleotide sequences of DNA

    • DNA

      • Deoxyribonucleic acid

      • Stores information for the synthesis of specific proteins

      • Found in the nucleus of the cell

      • Functions

        • Directs RNA synthesis

          • Transcription

        • Directs protein synthesis through RNA

          • Translation

    • Structure

      • Nucleic acids exist as polymers called polynucleotides

      • Each polynucleotide

        • Consists of monomers called nucleotides

        • Sugar + phosphate + nitrogen base

      • Nucleotide monomers

        • Made up of nucleosides (sugar + base) and a phosphate group

      • Nucleotide polymers

        • Are made up of nucleotides linked by the -OH on the 3’ carbon of one nucleotide and the phosphate on the 5’ carbon of the next

      • Gene

        • The sequence of bases along a nucleotide polymer

      • DNA double helix

        • Have two polynucleotides that spiral around an imaginary axis

        • Form a double helix

        • Consists of two antiparallel nucleotide strands

      • A, T, C, G

        • The nitrogenous bases in DNA

        • Form hydrogen bonds in a complementary fashion

          • A with T only

          • C with G only

  • DNA and Proteins as Tape Measures of Evolution

    • Molecular comparisons

      • Help biologists sort out the evolutionary connections among species

The Structure and Function of Macromolecules

  • Macromolecules

    • Are large molecules composed of smaller molecules

    • Are complex in their structure

    • Most macromolecules are polymers, built from monomers

    • Four classes of life’s organic molecules are polymers

      • Carbohydrates

      • Proteins

      • Nucleic acids

      • Lipids

    • A polymer

      • A long molecule consisting of many similar building blocks called monomers

      • Specific monomers make up each macromolecule

        • E.g. amino acids are the monomers for proteins

  • The Synthesis and Breakdown of Polymers

    • Monomers form larger molecules by condensation reaction called dehydration synthesis

    • Polymers and disassemble by hydrolysis

      • Addition of water molecules

    • Although organisms share the same limited number of monomer types, each organism is unique based on the arrangement of monomers into polymers

    • An immense variety of polymers can be built from a small set of monomers

  • Carbohydrates

    • Serve as fuel and building material

    • Include both sugars and polymers

      • Starch, cellulose, etc.

  • Sugars

    • Monosaccharides

      • Are the simplest sugars

      • Can be used for fuel

      • Can be converted into other organic molecules

      • Can be combined into polymers

      • Can be linear

      • Can form rings

    • Disaccharides

      • Consist of two monosaccharides

      • Are joined by a glycosidic linkage

    • Polysaccharides

      • Are polymers of sugars

      • Serve many roles in organism

    • Storage Polysaccharides

      • Starch

        • Is a polymer consisting entirely of glucose monomers

        • Is the major storage form of glucose in plants

      • Glycogen

        • Consists of glucose monomers

        • Is the major storage form of glucose in animals

      • Cellulose

        • Is a polymer of glucose

        • Has different glycosidic linkages than starch

        • Difficult to digest

          • Cows have microbes in their stomach to facilitate this process

      • Chitin

        • Is found in the exoskeleton of arthropods

        • Can be used as surgical thread

  • Lipids

    • Are the one class of large biological monomers that do not consist of polymers

    • Share the common trait of being hydrophobic

  • Fats

    • Constructed from two types of smaller molecules

      • A single glycerol and usually three fatty acids

    • Vary in length and number and location of double bonds they contain

    • Saturated fatty acids

      • Have the maximum number of hydrogen atoms possible

      • Have no double bonds

    • Unsaturated fatty acids

      • Have one or more double bonds

    • Phospholipids

      • Have only two fatty acids

      • Have a phosphate group instead of third fatty acid

      • Structure

        • Consists of a hydrophobic “head” and hydrophobic “tails”

        • Results in a bilayer arrangement founds in cell membranes

  • Steroids

    • Lipids characterized by a carbon skeleton consisting of four fused rings

    • Cholesterol

      • Found in cell membranes

      • Is a precursor for some hormones

  • Proteins

    • Proteins have many structures, resulting in a wide range of functions

    • Proteins do most of the work in cells and acts as enzymes

    • Proteins are made of monomers called amino acids

    • Enzyme

      • Type of protein that acts as a catalyst, speeding up chemical reactions

    • Polypeptides

      • Polymers of amino acids

      • A protein consists of one or more polypeptides

    • Amino acids

      • Are organic molecules possessing both carboxyl and amino groups

      • Differ in their properties due to differing side chains, called R groups

      • Linked by peptide bonds

  • Protein Conformation and Function

    • A protein’s specific conformation (shape) determines how it functions

  • Four Levels of Protein Structure

    • Primary structure

      • Unique sequence of amino acids in a polypeptide

    • Secondary structure

      • Folding or coiling of the polypeptide into a repeating configuration

      • Includes the a helix and β pleated sheet

    • Tertiary Structure

      • Overall three-dimensional shape of a polypeptide

      • Results from interactions between amino acids and R groups

    • Quaternary structure

      • The overall protein structure that results from the aggregation of two or more polypeptide subunits

  • Sickle Cell Disease

    • Results from a single amino acid substitution in the protein hemoglobin

  • What determines Protein Conformation

    • Protein conformation depends on the physical and chemical conditions of the protein’s environment

      • Temperature, pH, etc.

    • Denaturation is when a protein unravels and loses its native conformation

  • The Protein Folding Problem

    • Most proteins

      • Probably go through several intermediate states on their way to a stable conformation

      • Denaturated proteins no longer work in their unfolded conditions

      • Proteins may be denaturated by extreme changes in pH or temperature

    • Chaperonins

      • Protein molecules that assist in the proper folding of other proteins

    • X-ray crystallography

      • Used to determine a protein’s three-dimensional structure

  • Nucleic Acids

    • Store and transmit hereditary information

    • Genes

      • Are the units of inheritance

      • Program the amino acid sequence of polypeptides

      • Are made of nucleotide sequences of DNA

    • DNA

      • Deoxyribonucleic acid

      • Stores information for the synthesis of specific proteins

      • Found in the nucleus of the cell

      • Functions

        • Directs RNA synthesis

          • Transcription

        • Directs protein synthesis through RNA

          • Translation

    • Structure

      • Nucleic acids exist as polymers called polynucleotides

      • Each polynucleotide

        • Consists of monomers called nucleotides

        • Sugar + phosphate + nitrogen base

      • Nucleotide monomers

        • Made up of nucleosides (sugar + base) and a phosphate group

      • Nucleotide polymers

        • Are made up of nucleotides linked by the -OH on the 3’ carbon of one nucleotide and the phosphate on the 5’ carbon of the next

      • Gene

        • The sequence of bases along a nucleotide polymer

      • DNA double helix

        • Have two polynucleotides that spiral around an imaginary axis

        • Form a double helix

        • Consists of two antiparallel nucleotide strands

      • A, T, C, G

        • The nitrogenous bases in DNA

        • Form hydrogen bonds in a complementary fashion

          • A with T only

          • C with G only

  • DNA and Proteins as Tape Measures of Evolution

    • Molecular comparisons

      • Help biologists sort out the evolutionary connections among species

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