Chapter 2 Chemical Composition of the Body
Carbohydrates Organic molecules that contain carbon, hydrogen and oxygen General formula C n H 2n O n -ose denotes a sugar molecule
Supply energy Glucose Complex carbohydrates Provide structural support: cellulose Part of plasma membrane Monomer: monosaccarides
Monosaccharide: simple sugars Pentoses Ribose in RNA, Deoxyribose in DNA Hexoses: structural isomers Glucose, fructose and galactose Characteristics: Soluble, Sweet, Alcoholic fermentation Glucose: Also called Dextrose Transportable in the blood Blood glucose
C6H12O6
Fruit sugar C 6 H 12 O 6
C6H12O6
Disaccharides 2 monosaccharides joined covalently Sucrose : Glucose and fructose Maltose : Glucose and glucose Lactose : Glucose and galactose Characteristics: Sweet, Soluable, can be fermented Formation: called condensation Requires an enzyme, Removal of molecule of water Also called dehydration synthesis Formation of a covalent bond
Hydrolysis Reverse of dehydration synthesis Digestion reaction H 2 0 molecule split
Polysaccharides Many monosaccharides joined covalently General formula: (C 6 H 10 O 5 ) n Characteristics: Devoid of taste, do not form solutions, Iodine test: Iodine +starch blue Kinds Starch: Glucose subunits, branched Dextrins Glycogen (animal starch): Glucose subunits, Branched Cellulose: Glucose subunits, Long, unbranched chains
Proteins GR: proteios=first rank ~50% of the organic material of the body Functions Structural: Cell structures, connective tissues Functional: Enzymes, hormones, Hb Protein Structure polymers composed of amino acid subunits Amino Acid structure amino group (NH 2 ) carboxylic acid group (COOH) Radical group (R): functional group H
Proteins 20 different standard amino acids Based on the properties of the functional group
Proteins Dehydration synthesis Amino end of one amino acid combines with hydroxyl group of carboxylic end of another amino acid Peptide bond Bond between two adjacent amino acids
Peptide bond
Proteins Dipeptide: 2 amino acids Tripeptide: 3 amino acids Polypeptide: Number of amino acids varies Up to 100 aa Protein: Over 100aa, Great variety
Protein structure Primary structure Based on amino acid sequence Amino acid sequence determined by DNA Secondary structure Based on hydrogen bonding between close aa Tertiary structure 3-D shape Quaternary structure Only in proteins with 2 or more polypeptide chains
Secondary structure Based on the primary structure Weak hydrogen bonds form between hydrogen and oxygen of a different amino acid Two main kinds of secondary structure Alpha helix: Bond cause chain to twist in a helix. Beta pleated sheet: interactions between lengths of the polypeptide chain
Tertiary structure Polypeptide chains bend and fold Based on interactions with aa in different parts of the polypeptide chain disulfide bonds: covalent Hydrogen bonds: weak Produce 3-dimensional shapes Chemical interaction of each protein produces own characteristic tertiary structure Denaturing protein Irreversible disruption of tertiary structure
Bonds responsible for 3 o structure
Tertiary structure
Quaternary Structure Number of polypeptide chains covalently linked together Insulin, hemoglobin
Conjugated proteins Protein combined with another type of molecule Glycoproteins: carbohydrate with protein Membranes, hormone Lipoproteins: Lipid and protein Membranes, blood plasma Hemoproteins: iron and protein Hemoglobin, cytochromes
Nucleic Acids Include the macromolecules DNA: deoxyribonucleic acid RNA: ribonucleic acid Involved in heredity and genetic regulation Are polymers Monomeric subunit: nucleotides Bonded together in a dehydration synthesis reaction
Nucleotides Structure of a nucleotide: 3 subunits Pentose sugar Phosphate group Nitrogenous base Purines: two rings (Guanine, Adenine) Pyrimidines: one ring (Cytosine, Thymine, Uracil)
Nitrogenous Bases
DNA Huge molecules with simple structure, Big time data storage Structure Nucleotides: Pentose Deoxyribose Bases: Purines (G and A), Pyrimidines (C and T) Form double-stranded helix Nucleotide strands: Sugar-phosphate backbone Bases stick out Bases bond to each other Base pairing: A T, G C Called law of complementary base pairing
RNA Means by which DNA directs cellular activities Structure Pentose sugar: ribose Bases: uracil (not thymine) Single stranded Three main types Messenger RNA (mrna) Transfer RNA (trna) Ribosomal RNA (rrna)
DNA vs RNA