Chapter 2 - Chemical Composition of the Body PDF

Chapter 2 Chemical Composition of the Body  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Atoms Smallest units of matter that can undergo chemical change. Nucleus (center) contains: Protons (+ charge) Neutrons...

Chapter 2 Chemical Composition of the Body  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Atoms Smallest units of matter that can undergo chemical change. Nucleus (center) contains: Protons (+ charge) Neutrons (no charge) Atomic mass: Sum of protons and neutrons.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Atoms Atomic Number Number of protons in an atom Neutral atom Number of protons = number of electrons Isotopes Vary in number of neutrons Same in atomic number Vary in atomic mass  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Atoms Chemical element Includes all of the isotopic forms of a given atom Eg: Element Hydrogen: 3 isotopes Most common: one proton Deuterium: one proton, one neutron Tritium: one proton, two neutrons Commonly used in research 106 chemical elements  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Elements Four elements important to living organisms Carbon (C) Nitrogen (N) Oxygen (O) Hydrogen (H)  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Atoms Electrons (outside the nucleus): - charged Occupy orbitals surrounding nucleus. Valence electrons: Electrons in the outer most orbital that participate in chemical reactions (if orbit incomplete). Form chemical bonds.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Orbitals Also called shells or energy levels Electrons usually found within a given orbital Levels (and max number of electrons) First shell: 2 electrons Second shell: 8 electrons Third shell: usually 8 electrons Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chemical Bonds, Molecules, and Ionic Compounds Chemical bonds: Interaction of valence electrons between 2 or more atoms. # bonds determined by # electrons needed to complete outer orbital.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Covalent Bonds Atoms share their valence electrons. Nonpolar bonds: Electrons are equally distributed between the two identical atoms. Strongest bond. H2 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Covalent Bonds Polar bonds: Electrons are shared between two different atoms. Electrons may be pulled more toward more atom. Oxygen, nitrogen, phosphate pull electrons towards themselves. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ionic Bonds One or more valence electrons from an atom are completely transferred to a second atom. First atom loses electrons, + charged (cation). Second atom has more electrons,
- charged (anion).  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ionic Bonds Cation and anion attract, form ionic compound. Weaker than polar bonds. Dissociate easily when dissolved in H20. NaCl Na+ and Cl-  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Table Salt, an Ionically Bonded Molecule Slide number: 1 (–) (+) 11p 17p 11p 17p 12n 18n 12n + 18n Na + Cl NaCl Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Table Salt, an Ionically Bonded Molecule Slide number: 2 11p 17p 12n 18n Na + Cl Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Table Salt, an Ionically Bonded Molecule Slide number: 3 11p 17p 12n 18n Na + Cl Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Table Salt, an Ionically Bonded Molecule Slide number: 4 11p 17p 12n 18n Na + Cl Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Table Salt, an Ionically Bonded Molecule Slide number: 5 11p 17p 12n 18n Na + Cl Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Table Salt, an Ionically Bonded Molecule Slide number: 6 (+) (–) 11p 17p 12n 18n Na + Cl Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Table Salt, an Ionically Bonded Molecule Slide number: 7 (+) (–) 11p 17p 12n 18n NaCl Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Interaction with water Hydrophilic: Formation of hydration spheres. Polar covalent bonds. Hydrophobic: Cannot form hydration spheres. Nonpolar covalent bonds.  Hydrogen Bond Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Hydrogen forms a polar bond with another atom, hydrogen has a slight + charge. Weak attraction for for a second electronegative atom.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Acids, Bases, and the pH Scale Acid: Molecule that can release protons (H+). Proton donor. Base: Negatively charged ion that can combine with H+. Proton acceptor.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. pH pH = log _1__ [H+] Normal pH blood = 7.35 - 7.45. Buffer: System of molecules and ions that act to prevent changes in [H+].  Organic Molecules Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Molecules that contain carbon and hydrogen. Carbon has 4 electrons in outer orbital. Carbon covalently bonds to fill its outer orbital with 8 electrons.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Organic Molecules Organic Chemistry: deals with molecules that contain carbon More than 5 million organic compounds have been identified The carbon atom can form bonds with a greater number of different elements than any other type of atom Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Functional Groups Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Inactive “backbone” to which more reactive atoms are attached.  Classes According to Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Functional Groups Ketone and aldehyde: carbonyl group Organic acid: carboxyl group Alcohol: hydroxyl group  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Stereoisomers Exactly the same atoms arranged in same sequence. Differ in spatial orientation of a functional group. D-isomers: right-handed L-isomers: left-handed Enzymes of all cells can combine only with the L-amino acids and
D-sugars.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Four main classes of Organic molecules Lipids Carbohydrates Proteins Nucleic Acids  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lipids GR: Lipos=Fat Diverse group of molecules. Insoluble in polar solvents (H20). Hydrophobic (nonpolar) Consist primarily of hydrocarbon chains and rings.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lipids Hydrocarbons Fatty acids Triglycerides Ketone Bodies Phospholipids Steroids Prostaglandins  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Hydrocarbons Includes oils and gases Carbons can be single bonds (saturated) Carbons can be double bonded (unsaturated)  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fatty acids Nonpolar hydrocarbon chain Can be saturated (are stright) Can be unsaturated (bend at the double bond) Can be poly unsaturated (multiple bends) Carboxyl group on one end Large group Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Triglycerides Formed by condensation of glycerol and 3 fatty acids. Ester bond Fatty acid consists of hydrocarbon chain with carboxylic acid end. May be saturated or unsaturated Saturated fats: Mostly animal sources Mostly solid at room temperature Unsaturated fats Mostly plant sources Mostly liquid at room temperature Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nutritional considerations of triglycerides Also called fat or neutral fat Stored in adipose cells Total fat intake should be about 30% of total energy intake Saturated fat >10% Saturated fats are implicated in heart disease and stroke Data suggests they promote high blood cholesterol  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Phospholipids A number of categories All contain a phosphate group Most common Glycerol (3 carbons) Fatty Acids on carbon 1 and 2 Phosphate group attached to carbon (and other polar groups eg.: choline)  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lecithin  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Phospholipid Are amphipathic: contain both polar and nonpolar domains Head: contains polar groups Hydrophilic Tail: Contains fatty acids (nonpolar) Hydrophobic  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Phospholipids Major component of cell membranes Hydrophylic heads orient to water Hydrophobic tails orient to each other Kind of phospholipid varies based on cell or organelle  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Micelle formation  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ketone Bodies Results from the hydrolysis of triglycerides by adipocytes Liberates free FA into blood FA function as an acid in blood Most FA used as energy source by some tissues If not, converted by liver into Ketone bodies  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ketone Bodies 4-carbon chunks  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ketone Bodies Produced in the rapid breakdown of FA Low-carbohydrate diets Uncontrolled Diabetes mellitus Ketosis: Elevated level of FA in blood Ketoacidosis: ketosis is high enough to lower blood ph Can cause coma, death Filtered by the kidney  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Steroids Nonpolar and insoluble in H20. All have cholesterol as precursor.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Prostaglandins Prostaglandins: Fatty acid with cyclic hydrocarbon group. Derived from arachidonic acid.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Prostaglandins  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Carbohydrates Organic molecules that contain carbon, hydrogen and oxygen. CH20 General formula: CnH2nOn -ose denotes a sugar molecule  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Carbohydrates Supply energy Glucose Complex carbohydrates Provide structural support cellulose Part of plasma membrane Monomer: monosaccarides  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Carbohydrates Monosaccharide: the “simple sugars” Pentoses (5-carbons): Ribose: in RNA Deoxyribose: in DNA Hexoses (6-carbons):structural isomers Glucose, fructose and galactose Characteristics Soluable Sweet Alcoholic fermentation  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glucose Also called : Dextrose Transportable in the blood Blood glucose C6H12O6 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fructose Fruit sugar  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Galactose C6H12O6  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Carbohydrates Disaccharide: 2 monosaccharides joined covalently. Sucrose Glucose and fructose Maltose Glucose and glucose Lactose Glucose and galactose  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Disaccharides 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  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Formation of Disaccharides  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Hydrolysis Reverse of dehydration synthesis. Digestion reaction. H20 molecule split.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Carbohydrates Polysaccharides: Many monosaccharides joined covalently. General formula: (C6H10O5)n Characteristics: Devoid of taste Do not form solutions Iodine test Iodine +starch+blue  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Polysaccarides Kinds: Starch Glucose subunits branched Dextrins Glycogen (animal starch) Glucose subunits Branched Cellulose Glucose subunits Long, unbranched chains  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Proteins General Information: GR: proteios=first rank ~50% of the organic material of the body Functions Structural: Cell structures, CTs Functional: Enzymes, hormones, Hb, etc!  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Proteins Protein Structure Large molecules (polymers) composed of amino acid sub-units (monomers). Amino Acid structure amino group (NH2) carboxylic acid group (COOH) Radical group (R): functional group H Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Proteins 20 different standard amino acids. Based on the properties of the functional group E.g.:  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 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.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Peptide bond  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Proteins Dipeptide: 2 amino acids Tripeptide: 3 amino acids Polypeptide: many amino acids Number of amino acids varies Up to 100 aa Protein Over 100aa Great variety!  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Protein structure Four structural levels Primary structure Based on amino acid sequence Amino acid sequence determined by DNA Secondary structure Based on hydrogen bonding between close aa Tertiery structure 3-D shape Quaternary structure Only in proteins with 2 or more polypeptide chains Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Secondary structure (2o) 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  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Secondary structures  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Tertitary 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  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Bonds responsible for 3 o structure  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Tertiary structure  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Quaternary Structure Number of polypeptide chains covalently linked together. Insulin, hemoglobin  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 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  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 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  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nucleic Acids  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nucleotides Structure of a nucleotide: 3 subunits Pentose sugar Phosphate group Nitrogenous base Purines: two rings Guanine Adenine Pyrimidines: one ring Cytosine Thymine Uricil  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nucleotide Structure  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nitrogenous Bases  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. DNA Huge molecules with simple structure Big time data storage! Structure Nucleotides Pentose sugar: Deoxyribose Bases: Purines: G and A Pyrimidines: C and T Form double-stranded helix  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. DNA Nucleotide strands: 2 Sugar-phosphate backbone Bases stick out Bases bond to each other Base pairing: A–T G–C Called law of complementary base pairing  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nitrogenous Bases  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. DNA  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 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)  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. DNA vs RNA