INTRODUCTORY CHEMISTRY Pages 22 40 Introduction to Chemistry

INTRODUCTORY CHEMISTRY Pages 22 -40

Introduction to Chemistry � The science of structure and interactions of matter (anything that occupies space and has mass)

Chemical Elements and Atoms � Recall: � Chemical elements are substances that cannot be broken down into a simpler form by ordinary means � Chemical symbols are the one or two letters of the element’s name designated to represent that element

Chemical Elements and Atoms � 26 elements found in human body; 4 of them make-up 96% of the human body � Carbon 18% � Oxygen 65% � Hydrogen 10% � Nitrogen 3% � � Another 8 make-up 3. 8% And the final 14 make up 0. 2%, these are called trace elements

Ions, Molecules, and Compounds � Ion charged particle (atom) that has lost or gained an e� Example : Ca 2+; has given up two electrons � Molecules are formed when two or more atoms share electrons. Can be same elements sharing or different elements sharing � Recall: molecular formulas show number and type of atoms Example: 2 H 2 O 2 molecules of water composed of 2 atoms of hydrogen; one oxygen atom each � A compound is a molecule containing two or more different elements

Chemical Bonds � Forces that bind the atoms of molecules and compounds together, resisting their separation � Chemically stable atoms have 8 electrons in their outer shells, and unlikely to form chemical bonds � Atoms without 8 electrons in their outer shell form chemical bonds easily because they want eight (octet rule) � Three general types of chemical bonds: � Ionic bonds � Covalent bonds � Hydrogen bonds

Ionic Bonds � Force of attraction between ions of opposite charge � Cation: protons exceed electrons = positively charged atom � Anion: electrons exceed protons = negatively charged atom

Ionic Bonds in Human Body � Nnn Give strength to the tissue

Electrolytes � Most other ions in the human body are found dissolved in body fluids…. � Ionic compounds that break down into cations and anions when dissolved are called electrolytes; they can conduct an electrical current Function examples: �Control water movement within the body �Maintain acid-base balances �Produce nerve impulses �Transport nutrients �Support mental function �Convert calories into energy

Covalent Bonds � No electrons lost or gained; atoms form molecules by sharing one, two, or three pairs of their outer shell electrons � The more pairs shared the stronger the bond � Most common type of bonding in human body � Do not easily break apart in water (ionic bonds do)

Types of Covalent Bonds Between Atoms of the Same Element � Single covalent: two atoms share one electron pair � Double covalent: two atoms share two electron pairs � Triple covalent: two atoms share three electron pairs

Types of Covalent Bonds Between Atoms of the Different Elements � � Nonpolar covalent: atoms share equally one atom does not attract the shared electrons more strongly than the other atom Polar covalent: atoms share unequally one atom attracts the shared electron more strongly than the other

Hydrogen Bonds � Polar covalent bonds between hydrogen and other atoms is the third type of chemical bond � Hydrogen is slightly positively charged and attracts another atom with a slightly negative charge; attraction between oppositely charged parts of molecules rather than sharing of electron � � These are weak bonds Do not bind atoms into molecules; rather create a link between molecules or between different parts of a large molecule, like DNA

‘FREE RADICALS’ � � Defined: ion or molecule with an unpaired electron in its outermost shell; highly unstable; destructive to other nearby molecules…WHY? ? ? They will steal an electron or give one up to another ion or molecule thus damaging it

Where do free radicals come from? � � Produced during metabolic activity How? Exposure to certain substances in our environment can impede normal metabolic processes during which ions and molecules separate in our cells… � Sunlight � Automobile Exhaust � Cigarette Smoke � Alcohol Consumption � Emotional Stress � Exposure to Heavy Metals i. e. : Mercury, Cadium, Lead

Damage Caused by Free Radicals

� ANTIOXIDANTS!!!!!! � THEY NEUTRALIZE FREE RADICALS…

The Color of Antioxidants

All Antioxidants Are Not Equal � � � The antioxidants within food are not all the same. Some antioxidants prevent destruction, while others interrupt the effect of free radicals. Vitamin C, for example, breaks the chain reaction of free radical damage. Studies have shown that antioxidant supplements do not have the same beneficial effects as a diet full of fruits and vegetables. In fact, there are concerns that the amount of antioxidants, such as beta-carotene, ingested through a daily supplement may be unsafe. Therefore, it is important to consume a variety of foods with antioxidant qualities rather than take a supplement to get the beneficial effect.

Free Radicals and Aging � Many experts believe the aging process is due to free radicals that damage DNA and decrease organ function

Chemical Reactions � Occurs when new bonds form and/or old bonds break � Enables body structures to be built and functions to be carried out through energy transfers

Forms of Energy and Chemical Reactions � � ENERGY capacity to do work Two main forms: � Potential energy: energy stored by matter due to its position Example: sitting at the top of a slide waiting to go down � Kinetic energy: energy of matter in motion Example: sliding down the slide CHEMICAL ENERGY IS A FORM OF POTENTIAL ENERGY STORED IN THE BONDS OF MOLECULES

Four Types of Chemical Reactions � Synthesis Reaction (“to put together”) � Two or more atoms, ions, or molecules combine to form new and larger molecules (anabolic) � Decomposition Reaction � A molecule is split apart into smaller parts (catabolic)

Four Types of Chemical Reactions � Exchange Reaction � Consists of both synthesis and decomposition reactions � Reversible Reaction � Reactions that can go either way under different conditions, either building up or breaking down

Chemical Compounds and Life Processes � Chemicals in human body divided into two main classes of compounds: � Inorganic compounds Lack carbon Structurally simple Bonded ionically or covalently �Examples: water, many salts, acids, and bases �Exceptions: two-carbon compounds � carbon dioxide and bicarbonate ions � Organic compounds; contain carbon and usually also hydrogen Covalently bonded �Examples: carbohydrates, lipids, proteins, nucleic acids, and ATP (all macromolecules)

Inorganic Compounds � Water most important one physiologically, also most abundant compound in all living systems � 55% to 60% of body mass in lean adults � � Cells also are mostly composed of water WHY IS WATER THE MOST IMPORTANT? ? ?

Water � UNIQUE PROPERTIES…. due to its polar covalent bonds and its ‘bent’ shape (can interact with four or more ions or molecules) � Solvency Water. . continued Recall: �Solvent liquid or gas in which some other substance can dissolve �Solute substance that is dissolved in a solvent �Solution combination of a solvent and a solute Importance of the property physiologically: Carries nutrients, oxygen, and wastes throughout the body

Water. . continued � Excellent medium for chemical reactions; b/c dissolves so many substances � Medium for some decomposition and synthesis reactions Examples: �Digestion decomposition breaks down large nutrient molecules by adding water so they can be absorbed �Reaction called hydrolysis

Water. . continued � Absorbs and releases heat very slowly � Thus regulates body temperature = homeostasis � Requires a huge amount of heat to change form liquid to gas � Thus remains liquid sweat long enough to act cooling mechanism for body � Acts as a lubricant � Saliva, mucus, and others Important in thoracic and abdominal cavity, allow internal organs to touch and slide over one another Needed in joints, so bones, ligaments, and tendons can run against one another

Inorganic Acids, Bases, and Salts � � Acid: breaks apart; disassociates into one or more H+ ions in water Base: breaks apart; disassociates into one or more OH- ions in water � Acids and bases react together to form salts Example: NH 3 + HCl → NH 3 Cl Ammonia + Hydrochloric acid Ammonium chloride � Salt: breaks apart; disassociates into cations and anions in water; neither are H+ ions or OH- ions

Acid-Base Balance: the Concept of p. H � Homeostasis maintained through a balance between acid and base quantities in the human body � More H+ ions acidic (acidity); � More OH- ions basic (alkalinity) � Solutions acidity/alkalinity expressed as p. H � Recall p. H scale 0 to 14 p. H of 7 is neutral (pure water); H+ ions = OH- ions p. H below 7 acidic; H+ ions > OH- ions p. H above 7 basic (alkaline); H+ ions < OH- ions � Each whole number change on scale = 10 -fold change in number of H+ ions

Maintaining p. H: Buffer Systems � p. H level limits in body fluids very narrow in scope � Examples: Blood 7. 35 - 7. 45 Urine 6. 5 -7. 0 a. m. ; 7. 5 - 8. 0 p. m. Digestive system Lysosomes 4. 0 -4. 5 Cytosol 7. 2 - 7. 4 Mitochondrial matrix 7. 5 - 7. 8 Buffers convert strong acids and bases into weak acids and bases to maintain optimum p. H levels in body fluids �

Organic Compounds � � � Carbohydrates Lipids Proteins Enzymes Nucleic acids Adenosine triphosphate A F B E D C

Carbohydrates � Sugars, glycogen, starches, and cellulose � Contain C, H, and O (1: 2: 1 ratio; i. e. C 6 H 12 O 6) � Three major groups of carbohydrates: � Monosaccharides, simple sugars � Disaccharides, simple sugars � Polysaccharides, complex carbohydrates

Monosaccharides � Monomer of carbohydrates � Most important one=> glucose; source of chemical energy fro generating ATP � Others => ribose and deoxyribose used to make RNA and DNA

Disaccharides � Two monosaccharides bonded together covalently through dehydration synthesis � Can be broken back down into monosaccharides through hydrolysis

Polysaccharides � � Contain tens or hundreds of monosaccharides joined through dehydration synthesis; can be broken down through hydrolysis Main polysaccharides in human body => glycogen; made entirely of glucose � Stored in liver cells � Also in skeletal muscles Why do you think it is composed entirely of glucose; for what purpose? ? Plants make starches ; we consume them and break them down to glucose to be used as an energy source Cellulose is the polysaccharide found in plant cell walls, we cannot digest it… provides us with roughage to aid digestive processes

Lipids � � � Contain C, H, and O Hydrophobic (insoluble in water) because of fewer polar covalent bonds Includes: triglycerides (fats; solids and oils; liquids at room temperature) � Phospholipids � Steroids � fatty acids � fat-soluble vitamins (A, D, E, and K) � � � Provide body with chemical signals, insulation, padding and stored energy (two times as much as carbohydrates or proteins) Large amounts can contribute to heart & blood vessel disease

Triglycerides � Most plentiful in human body � Stored in fat tissue called adipose tissue Excess dietary carbohydrates, proteins, fats, and oils � � Composed of three fatty acids (hydrocarbon) & a 3 -C glycerol Fatty acids can be saturated, monounsaturated, or polysaturated

Saturated, Monounsaturated, and Polyunsaturated � Single covalent bonds between carbons Allows saturation of hydrogen atoms � Found mainly in animal products, mostly fats Also a few tropical plants: cocoa, palm, coconut � Solid at room temperature

Saturated, Monounsaturated, and Polyunsaturated � Monounsaturated (Unsaturated) � Contains one double covalent bond between two carbons Lowers hydrogen atom saturation � Usually liquid at room temperature � Examples: olive oil, peanut oil

Saturated, Monounsaturated, and Polyunsaturated � Polyunstaurated � More than one double covalent bond � Examples: canola oil, corn oil, safflower oil, sunflower oil, soybean oil

Phospholipids � Glycerol backbone with only two fatty acids attached to two carbons and a phosphate group attached to the third carbon Nonpolar fatty acids are hydrophobic “tails” Polar phosphate group are hydrophilic “heads” � Build body structures, make up cell membranes

Steroids � Have complex carbon skeleton with 4 rings � Cholesterol – steroid body cells uses to synthesize other steroids Examples: �Cells in ovaries synthesize estradiol (female sex hormone) �Leydig cells (found in testicles) synthesize testosterone (male sex hormone)

Proteins � Contain C, H, O, and N � Some also contain S � � Make up about ½ the body’s dry mass Serve a multitude of functions: � Structure of body cells; like muscles, tendons, bones, skin, etc. � Act as enzymes; speeding up chemical reactions � Aid in muscle contractions � Some are antibodies; others are hormones; gene regulators; components of blood

Amino Acid Structure � Building block (monomer) of proteins � Union of two or more amino acids produces a peptide bond United molecule composed of two amino acids called a dipeptide Three amino acids united called tripeptide More than three united called polypeptide; these form proteins �Sequence is crucial for proper function � � Made of amino group (NH 2), carboxyl group (COOH) and one of many side or “R” (radical) groups 20 different varieties of amino acids in human body

Protein function is highly sensitive to protein structure!!!

Protein Structure � Primary Protein Structure: � sequence of amino acids

� Secondary Protein Structure: � Sequence of amino acids linked by hydrogen bonds to form new shape, such as… Pleated sheath Helix

� Tertiary Protein Structure � Folded shape of protein when there attractions between alpha helices & pleated sheets � Denaturation occurs when hydrogen bonds holding shape together are broken

Denaturation The change in the shape of a protein molecule without breaking peptide bonds

Denaturation � Is irreversible! � Changes or halts what the protein does � Is caused by…

Heat, Detergents

� Quaternary Protein Structure � Protein consisting of more than one amino acid chain Model of myoglobin – an oxygen-storing protein found in muscles

Enzymes � Enzymes are proteins; usually end in –ase � Named � � � for type of chemical reaction they catalyze Speed up chemical reactions by increasing the frequency of collisions and by properly orienting the colliding molecules They are called catalysts because they speed up reactions without being altered themselves and can be used over and over again Important properties: specificity, efficiency, and control…

Specificity, Efficiency, and Control � Specificity: highly specific � Each enzyme catalyzes a particular chemical reaction that involves specific substrates (molecule upon which the enzyme acts) Specific products are produced Enzyme and substrate fit together like a lock-n-key � � Efficiency: single enzyme molecule can convert substrate molecules to products at rate of 600, 000 per second… Control: regulated by cell’s genes; sets rate of synthesis by enzymes and their concentration � Co factors/ coenzymes: non-protein substances affect rate at which inactive enzyme forms become active and visa versa Cofactors: ions of iron, zinc, magnesium, or calcium Coenzymes: niacin, riboflavin, derivatives of Vitamin B

Enzymes-Substrate Complex Enzymes are affected by…

Enzymes-Substrate Complex Enzymes are affected by… � � � � Heat p. H Concentration of substrate Competitive inhibitors Noncompetitive inhibitors Lack of cofactors Defective genes

Nucleic Acids: Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA) � � Contain C, H, O, N, and P Two types of nucleic acid: � � � DNA (deoxyribonucleic acid); double helix, 2 strands RNA (ribonucleic acid); one strand Nucleic acid molecule made up of repeating nucleotides DNA nucleotides consists of: four different nitrogenous bases (adenine, guanine, cytosine, and thymine), 5 -C sugar (deoxyribose), and a phosphate group � RNA nucleotides consists of: four different nitrogenous bases (adenine, guanine, cytosine, and uracil), 5 -C sugar (ribose), and a phosphate group � Nitrogenous bases are bonded together by hydrogen bonds � These carry genetic materials and transfer energy from food to body functions

Adenosine Triphosphate � � � “Energy Currency” of living organisms Main function: transfer energy from energy-releasing reactions to energy-requiring reactions that maintain cellular activities Examples: contraction of muscles, movement of chromosomes during cell division, movement of structures within a cell, transport of substances across cell membrane, and synthesis of larger molecules from small ones Adenosine composition = adenine + ribose Hydrolysis reduces ATP to ADP (adenosine diphosphate) thus releasing its stored energy ATP synthase and energy from glucose promotes the addition of a phosphate group to ADP to reenergize it to ATP