Chemistry of Living Things

Unit 2 Objectives  Relate importance of chemistry & biochemistry in health care  Define matter & energy  Explain structure of atom, element, compound  Describe main groups of organic compounds  Explain difference between DNA & RNA  Explain difference between acid, bases, salts  Describe why homeostasis is necessary  Define key words related to the chapter

Chemistry  Chemistry: –The study of the structure of matter & composition of substances, their properties and their chemical reactions –The chemical reactions necessary to sustain life occur in the cells  Biochemistry: –Study of the chemical reactions of living things

Matter & Energy  Matter: –Anything that has weight (mass) and occupies space. –Exists as solids, liquids, and gases –Neither created nor destroyed, but changes form through physical or chemical means

Matter & Energy  Energy: –Ability to do work or to put matter into motion –Potential energy: stored in cells waiting to be released –Kinetic energy: work resulting in motion

Atoms  Smallest piece of an element  Made up of subatomic particles: –Protons: (+) electric charge –Neutrons: no electric charge –Electrons: (-) electric charge  Protons & neutrons make up nucleus  Electrons arranged around nucleus in orbital zones or electron shells

Atoms  Protons equal to electrons and are electrically neutral  Can share or combine electron(s) with another atom to form a chemical bond

Atoms  Isotopes: –Atoms of a specific element that have same number of protons, but different number of neutrons –All isotopes of a specific element have same number of electrons  Radioactive isotopes: –Unstable & decay; emit energy as radiation –Radiation can be detected & computerized to form image of its distribution within body

Elements  Atoms that are alike combine to form elements  Can exist in more than one phase in our bodies –Bones contain Ca –Air in lungs contain oxygen

Compounds  Various elements combine in proportion by weight to form compounds –Water is 2 parts hydrogen and 1 part oxygen  Represented by formulas which shows types of elements & their proportions  Molecule: The smallest unit of a compound that still has the properties of the compound & the capability to lead its own stable existence

Types of Compounds  Inorganic compounds: –Made of molecules that do not contain carbon –Exceptions: CO2, & CaCO3 –Water is the most important inorganic compound as it comprises 55-65% of body weight  Organic compounds: –Always contain carbon combined with hydrogen & other elements –Main groups: carbohydrates, lipids, proteins, nucleic acids

Create Power Point  Sonography  Positron emission tomography (PET)  Computerized axial tomography (CAT)  Magnetic resonance imaging (MRI)  Will need: –Only 6 per group –Description –Explanation –Special instructions for the patient

Types of Organic Compounds

Carbohydrates  All carbs are compounds of the elements carbon, hydrogen & oxygen  Have 2x hydrogen as oxygen & carbon atoms  Subdivided into three groups: –Monosaccharides –Disaccharides –Polysaccharides

Carbohydrates  Monosaccharides –Simple sugars that cannot be broken down any further  Ex: glucose, fructose, galactose, ribose, deoxyribose –Glucose main source of energy  Carried by bloodstream to cells & stored as glycogen in liver & muscles cells  Combines w/ O2 (oxidation) to produce energy –Fructose found in fruit & honey –Deoxyribose found DNA –Ribose found in RNA

Carbohydrates  Disaccharides –Double sugar formed from two monosaccharide molecules  Dehydration synthesis: forming large molecule from small ones by loss of a molecule of water –Ex: sucrose, maltose, lactose –Must be broken down by digestion process to monosaccharides to be absorbed & used by body  Hydrolysis: large molecule broken down into smaller molecules by addition of water

Carbohydrates  Polysaccharides –Large, complex molecules of glucose molecules bonded together in one long chainlike molecule –Ex: starch, cellulose, glycogen –Can be broken down into monosaccharides under proper conditions

Lipids  Molecules containing the elements carbon, hydrogen, oxygen  Have much less oxygen in relation to hydrogen  Characteristics: –Important source of stored energy –Make up essential steroid hormones –Help insulate body  Ex: fats, phospholipids, steroids

Lipids  Fats: –Consist of glycerol & fatty acids –Triglyceride most abundant fat in body  Phospholipids: –Contain carbon, hydrogen, oxygen, & phosphorus –Found in cell membranes, brain & nerve tissue  Steroids –Lipids that contain cholesterol –Cholesterol essential in structure of semipermeable membrane of cell, manufacture of vitamin D, production of sex hormones, production of cortisol

Proteins  Organic compounds containing carbon, hydrogen, oxygen, nitrogen, phosphorus & sulfur  Found in every part of cell serving as binding & structural components  Amino acids: –small molecular units making up proteins –22 essential amino acids can combine in any number or sequence to make up proteins  Must be ingested-cannot be made by body

Enzymes  Organic catalyst: affects rate or speed of chemical reaction without being changed  Help provide energy for cell  Made of all protein or part protein (apoenzyme) attached to a nonprotein part (coenzyme)  Can be used over and over

Nucleic Acids  Contain elements carbon, oxygen, hydrogen, nitrogen, phosphorus  Two major types: –Deoxyribonucleic acid (DNA) –Ribonucleic acid (RNA)

Nucleic Acids  Structure: –Made of smaller repeating nucleotide subunits –Nucleotide subunits composed of three molecular groups  Group 1 a phosphate or phosphoric acid  Group 2 a five-carbon sugar  Group 3 a nitrogenous base of either purines or pyrimidines  Purines: adenine (A); guanine (G)  Pyrimidines: cytosine (C); thymine (T)

DNA Structure & Function  A double stranded molecule or double helix resembling twisted ladder  Sides formed by alternating bands of sugar units and phosphate units  Rungs formed by nitrogenous bases which always pair thymine w/ adenine; cytosine w/ guanine

DNA Structure & Function  DNA molecule passes on genetic information  Nucleus of every human cell contains 46 chromosomes (23 pairs), creating a long coiled molecule of DNA  Chromosomes contain about 100,000 genes which tells a cell what structure & function it will possess

RNA Structure & Function  Consists of a phosphate group, the ribose sugar, & one of the nitrogenous bases: adenine, cytosine, guanine, & uracil  Single stranded  Three types: –Messenger RNA (m-RNA): carries instructions for protein synthesis from nuclear DNA to ribosomes in cytoplasm

RNA Structure & Function  Three types (cont): –Transfer RNA (t-RNA): picks up amino acid molecules in cytoplasm & transfers them to ribosomes where they combine to form proteins –Ribosomal RNA (r-RNA): helps in attachment of m-RNA to ribosomes

Acids, Bases, and Salts

Acids  A substance that, when dissolved in water, will ionize into positively charged hydrogen ions and negatively charged ions of some other element  A substance that yields hydrogen ions in solution  May have a sour taste

Acids  Common Acids –Acetic: found in vinegar –Boric: weak eyewash –Carbonic: carbonated beverages –Hydrochloric: in stomach –Nitric: industrial oxidizing acid –Sulfuric: batteries

Bases  Also known as an alkali  When dissolved in water, ionizes into negatively charged hydroxide ions & positively charge ions of a metal  May have bitter taste & feel slippery

Bases  Common bases: –Ammonium hydroxide: household liquid cleaners –Magnesium hydroxide: MOM –Sodium hydroxide: Lye

Salts  Neutralization: when an acid & base combine to form a salt & water  Hydrogen ions from the acid & hydroxide ions from the base join to form water  Negative ions of the acid combine with positive ions of base to form salt  HCL + NaOH= NaCl + H2O

pH Scale  pH: measure of acidity or alkalinity of a solution i.e. number of hydrogen ions in solution  pH scale: –ranges from 0 to 14 –7 is neutral (equal hydrogen & hydroxide ions) –0 to 6.9 indicates an acidic solution & higher hydrogen ion concentration –7.1 to 14.0 indicates an alkaline (basic) solution & lower hydrogen ion concentration

Buffers  Buffers help maintain a constant pH value, which contributes to homeostasis or balanced state within all living things  When there is either excess acid or base, buffers help neutralize the excess acid or base until eliminated by respiratory or urinary systems

Buffers  Four sets of buffers: –Alkaline & acid phosphate –Proteins –Bicarbonate-carbonic acid –Hemoglobin