hemistry Basics for Anatomy & Physiology 1
Why study chemistry in A&P? - Body functions depend on cellular functions - ellular functions result from chemical changes - Biochemistry helps to explain physiological processes - Because we all are just giant bags of 2
tructure of Matter Matter anything that takes up space and has mass (weight). It is composed of elements. Elements composed of chemically identical atoms: Bulk elements required by the body in large amounts Trace elements - required by the body in small amounts Ultratrace elements required by the body in very minute amounts Atoms smallest particle of an element 3
Elements 4
ome Particles of Matter 5
Atomic tructure Atoms - composed of subatomic particles: Proton carries a single positive charge eutron carries no electrical charge Electron carries a single negative charge ucleus entral part of atom omposed of protons and neutrons Electrons move around the nucleus 0 + - 0 + - 0 0 + Lithium (Li) - eutron (n 0 ) Proton (p + ) Electron (e ) ucleus 6
Atomic umber umber of protons in the nucleus of one atom Each element has a unique atomic number Equals the number of electrons in the atom Atomic umber and Atomic Weight Atomic Weight The number of protons plus the number of neutrons in one atom Electrons do not contribute to the weight of the atom 7
Isotopes Isotopes Atoms with the same atomic numbers but with different atomic weights Atoms with the same number of protons and electrons but a different number of neutrons xygen often forms isotopes ( 16, 17, and 18 ) Unstable isotopes are radioactive; they emit energy or atomic fragments 9
Molecules and ompounds Molecule particle formed when two or more atoms chemically combine ompound particle formed when two or more atoms of different elements chemically combine Molecular formulas depict the elements present and the number of each atom present in the molecule 2 6 12 6 2 10
Bonding of Atoms Bonds form when atoms combine with other atoms Electrons of an atom occupy regions of space called electron shells which circle the nucleus For atoms with atomic numbers of 18 or less, the following rules apply: The first shell can hold up to 2 electrons The second shell can hold up to 8 electrons The third shell can hold up to 8 electrons 11
Bonding of Atoms Lower shells are filled first If the outermost shell is full, the atom is stable - - - + 0 + + 0 0 + 0 + 0 0 + - - - ydrogen () elium (e) Lithium (Li) 12
Bonding of Atoms force that holds atoms together depends on the number of electrons in the valence shell 8 electrons is chemically stable ctet rule (most prevalent in elements with atomic number <20) 13
Bonding of Atoms: Ions Ion An atom that gains or loses electrons to become stable An electrically charged atom ation A positively charged ion Formed when an atom loses electrons 11p + 12n 0 17p + 18n 0 Anion A negatively charged ion Formed when an atom gains electrons odium atom (a) hlorine atom (l) (a) eparate atoms If a sodium atom loses an electron to a chlorine atom, the sodium atom becomes a sodium ion (a + ), and the chlorine atom becomes a chloride ion (l ). 14
Ionic Bonds Ionic Bonds An attraction between a cation and an anion Formed when electrons are transferred from one atom to another atom 11p + + 17p + 12n 0 18n 0 a + l odium ion (a + ) hloride ion (l ) (c) alt crystal Ionically bonded substances form arrays such as a crystal of al. odium chloride (b) Bonded ions These oppositely charged particles attract electrically and join by an ionic bond. 15
ovalent Bonds Formed when atoms share electrons Most common bond in the body trongest 16
ovalent Bonds - - 2 - + + + + - ydrogen atom + ydrogen atom ydrogen atoms form single bonds xygen atoms form two bonds itrogen atoms form three bonds arbon atoms form four bonds ydrogen molecule = = = 17
Bonding of Atoms: tructural Formula tructural formulas show how atoms bond and are arranged in various molecules 2 2 2 2 18
Bonding of Atoms: Polar Molecules Polar Molecules Molecule with a slightly negative end and a slightly positive end Results when electrons are not shared equally in covalent bonds (if shared equally nonpolar) Water is an important polar molecule lightly negative end (a) lightly positive ends 19
ydrogen Bonds ydrogen Bonds A weak attraction between the positive end of one polar molecule and the negative end of another polar molecule Formed between water molecules Important for protein and nucleic acid structure ydrogen bonds (b) 20
hemical Reactions hemical reactions occur when chemical bonds form or break among atoms, ions, or molecules. Based on valence electrons Reactants are the starting materials of the reaction - the atoms, ions, or molecules Products are substances formed at the end of the chemical reaction al a + + l - Reactant Products 21
Types of hemical Reactions ynthesis Reaction more complex chemical structure is formed A + B AB Decomposition Reaction chemical bonds are broken to form a simpler chemical structure AB A + B Exchange Reaction chemical bonds are broken and new bonds are formed AB + D AD + B Reversible Reaction the products can change back to the reactants A + B AB 22
Types of hemical Reactions Redox Reaction Reactions involving the transfer of electrons (oxidation state changed) xidation is the loss of electrons Reduction is the gain of electrons Many biological processes are redox reactions ellular respiration is the oxidation of glucose and the reduction of oxygen to water Also reduction of AD + to AD and oxidation of AD to AD + 23
hemical onstituents of ells rganic v. Inorganic Molecules rganic molecules ontain and Usually larger than inorganic molecules Dissolve in water and organic liquids arbohydrates, proteins, lipids, and nucleic acids Inorganic molecules Generally do not contain Usually smaller than organic molecules Usually dissociate in water, forming ions Water, oxygen, carbon dioxide, and inorganic salts 24
Inorganic ubstances Water Most abundant compound in living material Two-thirds of the weight of an adult human Major component of all body fluids Medium for most metabolic reactions Important role in transporting chemicals in the body Absorbs and transports heat xygen ( 2 ) Used by organelles to release energy from nutrients in order to drive cell s metabolic activities ecessary for survival 25
Inorganic ubstances arbon dioxide ( 2 ) Waste product released during metabolic reactions Must be removed from the body Inorganic salts Abundant in body fluids ources of necessary ions (a +, l -, K +, a 2+, etc.) Play important roles in metabolism 26
Acids, Bases, and alts Electrolytes substances that release ions in water al a + + l - Acids electrolytes that dissociate to release hydrogen ions in water (proton donor) l + + l - Bases substances that release ions that can combine with hydrogen ions (proton acceptor) a a + + - alts electrolytes formed by the reaction between an acid and a base l + a 2 + al 27
Acid and Base oncentration p scale - indicates the concentration of hydrogen ions in solution eutral p 7; indicates equal concentrations of + and - Acidic p less than 7; indicates a greater concentration of + Relative Amounts of + (red) and (blue) Acidic + 2.0 gastric juice Basic or alkaline p greater than 7; indicates a greater concentration of - 3.0 apple juice 4.2 tomato juice 5.3 cabbage 6.6 cow s milk 6.0 corn 8.4 7.4 odium uman biocarbonate blood 8.0 7.0 Egg Distilled white water 10.5 milk of magnesia 11.5 ousehold ammonia p 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Acidic + concentration increases eutral concentration increases Basic (alkaline) 28 Basic
rganic ubstances arbohydrates Provide energy to cells upply materials to build cell structures Water-soluble ontain,, and Ratio of to close to 2:1 ( 6 12 6 ) Monosaccharides glucose, fructose Disaccharides sucrose, lactose Polysaccharides glycogen, cellulose 29
rganic ubstances arbohydrates (a) ome glucose molecules ( 6 12 6 ) have a straight chain of carbon atoms. (b) More commonly, glucose molecules form a ring structure. (c) This shape symbolizes the ring structure of a glucose molecule. 30
rganic ubstances arbohydrates (a) Monosaccharide (b) Disaccharide (c) Polysaccharide 31
rganic ubstances Lipids 32 oluble in organic solvents; insoluble in water Fats (triglycerides) Used primarily for energy; most common lipid in the body ontain,, and but less than carbohydrates ( 57 110 6 ) Building blocks are 1 glycerol and 3 fatty acids per molecule aturated and unsaturated Glycerol portion Fatty acid portions
Phospholipids rganic ubstances Lipids Building blocks are 1 glycerol, 2 fatty acids, and 1 phosphate per molecule ydrophilic and hydrophobic Major component of cell membranes Fatty acid Glycerol portion Fatty acid Fatty acid Fatty acid Fatty acid P Phosphate portion Water-insoluble (hydrophobic) tail Water-soluble (hydrophilic) head (a) A fat molecule (b) A phospholipid molecule (the unshaded portion may vary) (c) chematic representation of a phospholipid molecule 33
rganic ubstances Lipids teroids Four connected rings of carbon Widely distributed in the body, various functions omponent of cell membrane Used to synthesize hormones holesterol 2 2 2 3 2 3 3 2 2 2 2 2 3 3 2 2 (a) General structure of a steroid (b) holesterol 34
rganic ubstances Proteins tructural material Energy source ormones Receptors Enzymes Antibodies Protein building blocks are amino acids Amino acids held together with peptide bonds R (a) General structure of an amino acid. The portion common to all amino acids is within the oval. It includes the amino group ( 2 ) and the carboxyl group ( ). The "R" group, or the "rest of the molecule, is what makes each amino acid unique. (b) ysteine. ysteine has an R group that contains sulfur. Phenylalanine. Phenylalanine has a complex R group. Improper metabolism of phenylalanine occurs in the disease phenylketonuria. 35
rganic ubstances Proteins Four Levels of Protein tructure Amino acids (a) Primary structure Each oblong shape in this polypeptide chain represents an amino acid molecule. The whole chain represents a portion of a protein molecule. (c) Tertiary structure The pleated and coiled polypeptide chain of a protein molecule folds into a unique threedimensional structure. (b) econdary structure The polypeptide chain of a protein molecule is often either pleated or twisted to form a coil. Dotted lines represent hydrogen bonds. R groups (see fig. 2.17) are indicated in bold. Pleated structure R R R R R R R R R R oiled structure R R R R R R R Three-dimensional folding (d) Quaternary structure Two or more polypeptide chains may be connected to form a single protein molecule. 36
rganic ubstances ucleic Acids arry genes Encode amino acid sequences of proteins Building blocks are nucleotides P B DA (deoxyribonucleic acid) double polynucleotide RA (ribonucleic acid) single polynucleotide 37
rganic ubstances ucleic Acids 38 P P P P P P B B B B B B P P P P P P B B B B B B (b) P P P P P P B B B B B B (a)