Basic Chemistry of Life

Matter & Energy Matter Energy Anything that occupies space & has mass Composes elements C,H,O & N make up 96% of human mass C,H,O,N,P & Ca make up 99% of human mass Can undergo physical & chemical changes Energy The ability to do work – puts matter into motion Kinetic Energy: energy doing work Potential Energy: stored energy All living things are built of matter & require energy to grow & function

Elements & Atoms Smallest unit of an element is an atom Atomic Structure: Nucleus – consists of protons (+) & neutrons (o) Electron cloud – electrons (-) orbit the nucleus in specific energy levels Atomic # = # of protons #protons = # of electrons Atomic mass = # of protons + # of neutrons

Molecules & Compounds Molecule Compound Smallest unit of two or more combined atoms Ex: H2, C6H12O6, O2 Compound A molecule containing two or more different kinds of atoms Ex: CH4, H2O Compounds have unique properties that are different from the elements that compose them.

Chemical Bonds The electrons are the part of the atom involved in bonding. Types of Bonds: Ionic Bonds Electrons are transferred from one atom to another Covalent Bonds Pairs of valence electrons are shared between atoms. Most bonds in living organisms are covalent Hydrogen Bonds (weak bonds) Provide temporary bonding between certain atoms in large complex molecules such as proteins & nucleic acids

Chemical Reactions The formation & breakdown of compounds. Synthesis Reaction (A + B = AB) Decomposition Reactions (AB = A + B) Exchange Reactions (AB + C = AC + B) Metabolism – sum of all chemical reactions in the body. Formation of bonds requires energy Breaking of bonds releases energy

Types of Chemical Compounds Inorganic Compounds Lack carbon & contain ionic bonds Resist decomposition Ex: water, salts, & many acids & bases Organic Compounds Contain carbon & usually hydrogen Covalently bonded Ex: Carbohydrates, lipids, proteins, & nucleic acids Both are equally essential to life!

Inorganic Compounds Water Acids, Bases, & Salts (electrolytes) Most abundant substance in the body Excellent solvent & suspension medium Important in chemical reactions, absorbs & releases heat, lubricates, and protects Acids, Bases, & Salts (electrolytes) Form ions in water – Acids (H+) and Bases (OH-) pH of different parts of the body must remain constant Buffer system eliminates excess H+ ions and OH- ions in order to maintain pH homeostasis

Formation & Breakdown of Organic Molecules Built by bonding small molecules together to form long chains called polymers (like a string of pearls) Dehydration Synthesis A bond forms from the loss of a water molecule Ex: protein synthesis Hydrolysis Breaking bonds with the addition of a water molecule Ex: digestion

Organic Compounds: Carbohydrates Sugars & starches composed of carbon, hydrogen, & oxygen Store & release energy – 3 types Monosaccharides – simple sugars Building blocks of carbohydrates Ex: glucose & fructose Disaccharides – two simple sugars Ex: sucrose, lactose, maltose Polysaccharides – many sugars Long branching chains of monosaccharides Ex: starch & glycogen

Organic Compounds: Lipids Fats, phospholipids, & steroids. Composed of lots of carbon & hydrogen, with less oxygen. C57H110O6 Protect, insulate, & provide long-term energy storage Types: Triglycerides 3 fatty acids & glycerol Phospholipids 2 fatty acids, glycerol, & a phosphate group Steroids – 4 rings (cholesterol)

Lipids Continued Saturated Fats – fatty acid chains of carbon with only single bonds Generally solid at room temperature Ex: butter & steak fat Unsaturated Fats – fatty acid chains of carbon with double bonds Generally liquid at room temperature (oils) Ex: peanut oil, corn oil, olive oil, etc…

Organic Compounds: Proteins 50% of the organic matter in the body Contain C, H, O, N, & sometimes S Composed of long chains of amino acids Uses: Make up cell membranes Build structures (like muscles) Carry out metabolic processes (enzymes carry out chemical reactions) Defensive of the body There are 1000ths of different proteins each with a unique shape & function. Ex catalase, lactase, amylase, hemoglobin, actin, etc…

Enzymes & Substrates Proteins that speed-up chemical reactions Enzymes are specific for the reactant they work with (like a lock & a key). Depends on the enzyme’s shape The reactant that an enzyme works with is called its substrate Only one type of substrate will fit each enzyme The substrate fits into a region of the enzyme called the active site.

Factors Affecting Enzymes Temperature There is an optimum temperature for enzyme reactions pH There is an optimum pH for enzyme reactions Amount of enzymes The more enzymes available the faster the reaction Amount of substrate The more substrate available the faster the reaction Changes in temperature or pH may cause enzymes to become “denatured” Changes enzymes shape & they can no longer bind to the substrate…will render the enzymes functionless

Nucleic Acids Organic compound composed of Nucleotides Sugar, phosphate, & nitrogen base Types: DNA & RNA DNA – double helix Organism’s information code RNA – single helix Involved in protein synthesis

ATP: Adenosine Triphosphate Major energy storing molecule in living things Used in all life processes Consists of an Adenine, a ribose sugar, & three phosphate groups Formation of ATP – stores energy Breakdown of ATP – releases energy