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Atoms and Molecules General What are you? a collection of carefully arranged atoms and molecules How does your body work? all physiology from organism to cell involves chemical reactions the physiology of the organism is just the sum total of all the chemical reactions occurring in individual cells to maintain “yourself” you must continually replenish nutrients takes energy to do that So, food contains both nutrients or building blocks and molecules that can be used to make energy the whole process is regulated by your “genes” – the genetic information contained within each cell tells what to do and what is needed to do it assembly instructions as long as you give your body the energy and nutrients it needs it can run “automatically” Nutrient A nutrient is any component of the food that we eat that our body needs to function properly some of these nutrients are individual atoms or elements some of these nutrients are molecules that we need but that our body is unable to make for itself some of these nutrients we use mainly as “building blocks” some cells functions by manipulating energy and matter = metabolism Biochemistry: Atoms & Molecules, Ziser, 2003 1 “homeostasis” keeps all systems and processes in balance What nutrients do we need? start by looking at the composition of body: the body is mainly made up of water and organic molecules Human body (100 lbs): 100% Atoms and Inorganic Molecules 65%/lbs 62 lbs water 2.5 lb minerals & inorganics (59-62%) (2.5%) Organic Molecules 18 lbs fat 35%/lbs 1.5 lbs carbos 16 lbs proteins .5 lb nucleic acids (14-20%) another source says 18-30 (1-2%) another source says 2-3 (15-18%) another source says 12-30 (<1%) more basic: what are these made of? elements (atoms) water: H & O organic molecules: C, H, O, N, P minerals: Ca, Fe, Mg, Cu, Zn, etc nutrient = any of the atoms or molecules that the body requires to function properly some of the nutrients we eat are individual atoms or elements some are molecules that our body needs but cannot make itself Essential vs Nonessential Nutrients the body can make some molecules itself given proper elements Biochemistry: Atoms & Molecules, Ziser, 2003 2 45 –50 different nutrients are essential nutrients can’t make them ourselves must be in food eg. basic elements, some molecules Elements: macronutrients micronutrients C 18.5% Cr, Co H 9.5% Cu, F O 65% Mo, Se N 3.2% Si, Sn (tin) P 1.0% Zn, V Ca 1.5% Molecules: O2 (oxygen gas) vitamins 8 amino acids 10 essential in children 8 essential in adults 2 fatty acids What does it use them for? mainly to make organic molecules: proteins carbohydrates fats etc. [not vitamins] What about energy? where does our body get the energy to do this? same So food contains two things: nutrients (=building blocks) energy what kinds of energy does body use: mechanical muscles electrical nerves chemical all cells where does this energy come from? food = chemical energy Biochemistry: Atoms & Molecules, Ziser, 2003 3 bonds: break bonds release energy form bonds use (store) energy Chemical Bonds atoms combine to form molecules by forming chemical bonds: electrons in various orbitals of different atoms interact in specific ways = bonds such bonds depend on an atom’s electrons characteristics outer electrons -most potential energy -most likely to form bonds all atoms are in constant motion when they “bump” into each other they may react to form molecules thus a chemical bond: is not an OBJECT is an ENERGY RELATIONSHIP 1. covalent bonds electrons are shared between atoms most bonds single, double or triple can be nonpolar or polar most stable kind of bond (bond energy = 80-110 kcal/mole) 2. ionic bonds when an atom gives up electron to another no such thing as a “molecule” of salt, in water the ions disperse, only held together in crystal form [oxidation e- given up; eg Na is a reducing agent for Cl] [reduction receives e-; Cl reduces Na] cation = + charged ions anions = - charged ions [Na; atomic # = 11] [Cl ; atomic # = 17] redox also may involve H atoms transferred (bond energy = 5 kcal/mole) Biochemistry: Atoms & Molecules, Ziser, 2003 4 3. hydrogen bonds contains about 5% the strength of covalent bonds occur between polar molecules (covalent bonds) some molecules have an uneven distribution of electrons in covalent bondspolar hydrogen bonds tend to draw molecules or parts of molecules together serve as bridges between different molecules or different parts of same molecule can be formed or broken easily extremely important in stability of many large organic molecules also give some unique properties to molecues eg. Water (bond energy = 4-6 kcal/mole) Biochemistry: Atoms & Molecules, Ziser, 2003 5 Chemical Reactions Chemical bonds are formed or broken in chemical reactions: a chemical reaction is any process in which some chemical bons are broken or made A. synthesis – combining to form more complex substances A + B AB eg. dehydration synthesis (condensation) eliminates water to synthesize larger molecules uses energy B. decomposition – break down into simpler substances AB A + B eg. hydrolysis uses water to break down larger molecules releases energy C. displacement or exchange A + BC AC + B D. reversible Metabolism = synthesis + decompositon Biochemistry: Atoms & Molecules, Ziser, 2003 6