Chemistry of Living Things Pages 14 – 28 Chapter 2

Page 15 Chemistry Chemistry = the study of the structure of matter, the composition of substances, their properties, & their chemical reactions. Many chemical reactions occur in the human body Digestion Formation of urine Manufacture of protein Biochemistry = the study of the chemical reactions of living things. To be an effective health care professional, an individual must have a thorough understanding of the normal & abnormal functioning of he human body & knowledge of basic chemistry & biochemistry

Page 15 Matter & Energy Matter = anything that has weight (mass) & occupies space. Exists in solid, liquid, & gas forms. Neither created nor destroyed, but it can change form through physical or chemical means. Physical change = breaking something into smaller pieces such as chewing up food Chemical change = change of composition of something (example: digestion of the food in the stomach & small intestine)

Matter & Energy (Cont’d) Page 15 Matter & Energy (Cont’d) Energy = the ability to do work or to put matter into motion. Potential energy = energy stored in cells waiting to be released (lying in bed) Kinetic energy = work resulting in motion (getting out of bed)

Page 15 Atoms Atom = Smallest piece of an element; invisible to the human eye. Subatomic particles: Protons = have a positive (+) electric charge; found in the nucleus of an atom (# = to the # of electrons) Neutrons = have no electric charge; found in the nucleus of an atom Electrons = have a negative (–) electric charge; arranged around the nucleus in orbital zones or electron shells (# = to the # of protons) The number & arrangement of the subatomic particles dictate how the atoms of one element differ from atoms of another element

Figure 2 – 1 Structure of the Atom Page 14 Figure 2 – 1 Structure of the Atom

Page 15 Atoms Isotopes = atoms of a specific element that have the same number of protons but a different number of neutrons (all isotopes of a specific element have the same number of electrons) Radioactive isotopes = certain isotopes that are unstable & decay (come apart). As they decay they give off (emit) energy in the form of radiation, which can be picked up by a detector. Nuclear medicine is a branch of medicine that uses radioactive isotopes to prevent, diagnose, & treat disease. The detector not only detects the emission from a radioactive isotope, but, with the aid of a computer, also forms the image of its distribution within the body. Radio active isotopes can be used to study the structure & function of particular tissues. The most common uses of isotopes are for the treatment of thyroid conditions, prostate cancer, & cancer bone pain. Radioactive isotopes enable the physician to point the selected isotopes directly at the disease & destroy the disease tissue.

Medical Highlights Page 16 Medical Imaging = the noninvasive techniques & processes used to create images of the human body for clinical purposes. CAT scan or CT scan MRI PET scan Bone, liver, brain, and spleen scans Sonography or ultrasound Mammograms (Chapter 21)

Pages 15 – 17 Elements Element = a substance that can neither be created nor destroyed by ordinary chemical means. Atoms that are alike are combined to form the this stage of matter. 92 elements are found naturally in our world Each element is represented by a chemical symbol or an abbreviation.

Page 17 Compounds Compounds = various elements can combine in a definite proportion by weight; they have different characteristics or properties depending on the elements in them. Compounds are represented by formula. Unicellular (one-celled microbe) & multicellular (many celled animal or plant) can be compared with a chemical formula Organic compounds = compounds found in living things contain the element carbon Most living organisms will take the 20 essential elements & change them into needed compounds for the maintenance of the organism

Page 17 Molecules Molecules = the smallest unit of a compound that still has the properties of the compound & the ability to lead its own stable & independent existence

Page 17 Chemical Bonds Chemical bonds = atoms can share or combine their electrons with atoms of other elements to form these bonds Ionic bond = One atom gives up an electron to another atom; that atom will now have more protons than electrons & will have a positive (+) charge. The atom that took the extra electron will now have more electrons than protons & thus have a negative (–) charge. Ion = the positively or negative charged particle Ionically bonded atoms disassociate when immersed in water

Page 18 Figure 2 – 2 Ionic Bond

Chemical Bonds (Cont’d) Pages 17 – 18 Chemical Bonds (Cont’d) Covalent bond = The atoms share electrons Molecules containing covalent bonds do not form ionic bonds & do not disassociate when immersed in water. Hydrogen bond = Helps hold water molecules together; very weak bonds Ionically bonded atoms disassociate when immersed in water

Page 18 Electrolytes Electrolytes = Electrically charged particles that help determine acid-base balance When electrolytes are in a solution they can conduct an electrical charge; Make it possible for materials to be broken down, altered & recombined to from new substances or compounds

Types of Compounds Pages 18 – 19 Inorganic compounds – nonliving Normally do not contain carbon (exceptions include CO2 & CaCO3) Water makes up 55–65% of our body weight universal solvent Required for homeostasis Organic compounds –living Always have carbon Four main groups are carbohydrates, lipids, proteins & nucleic acids

Page 19 Carbohydrates Are compounds of the elements carbon, hydrogen, & oxygen (has twice as many hydrogen atoms as the others) Monosaccharides = Simple sugars, e.g., glucose Disaccharides = Two monosaccharide molecules, e.g., sucrose Polysaccharides = Complex molecules e.g., starch

Page 20 Lipids Molecules containing the elements carbon, hydrogen, & oxygen (contain much less oxygen than hydrogen) Fats (triglycerides) = consist of glycerol & fatty acids & make up 95% of fats in the human body Phospholipids = contain carbon, hydrogen, oxygen, & phosphorus. Found in cell membranes, the brain, & nervous tissue Steroids = lipids contain cholesterol Fats are essential for life

Page 20 Proteins Compounds containing the elements carbon, hydrogen, oxygen, & nitrogen (& often, phosphorus and sulfur) Most diverse & essential organic compounds Found in every living part of a living cell Amino acids = small molecular units that work together to build proteins in the body. 20 different amino acids are combined in any number & sequence to make up all the types of protein. Essential & non-essential Essential = must be obtained from dietary sources & cannot be made up by the body non-essential = are those the body can manufacture. Protiens can be 300 amino acids or thousands long

Enzymes Pages 20 – 21 These are specialized protein molecules Found in all living cells Organic catalysts Help control chemical reactions Provide energy for cellular functions Highly specific in their actions Affect the rate or speed of a chemical reaction without being changed itself. Can be used over & over Made up of a protein attached to a nonprotein part

Page 21 Nucleic Acids Organic compounds that contain carbon, oxygen, hydrogen, nitrogen, & phosphorus Structure of nucleic acids Largest known organic molecules Made up of smaller subunits called nucleotides Deoxyribonucleic acid Ribonucleic acid

Nucleic Acids (Cont’d) Page 21 Nucleic Acids (Cont’d) DNA Structure & Function – double stranded Double helix (twisted ladder) The sides of the ladder are made by alternating bands of sugar unit & a phosphate unit. The rungs of the ladder are made from nitrogenous bases that always pair in very specific order Thymine pairs with Adenine & Cytosine pairs with Guanine Involved in process of heredity Deoxyribonucleic acid

Figure 2 – 5 Schematic of DNA Page 21 Figure 2 – 5 Schematic of DNA

Nucleic Acids (Cont’d) Pages 21 – 22 Nucleic Acids (Cont’d) RNA structure & Function – single stranded Consists of a phosphate group, the ribose sugar, & any one of the following nitrogenous bases: adenine, cytosine, guanine, & uracil instead of thymine. messenger RNA = carries the instruction for protein synthesis transfer RNA = picks up amino acids in the cytoplasm & transfers them to the ribosome ribosomal RNA = helps with the attachment of m-RNA to the ribosome. Ribonucleic acid

Page 22 Acids Acids = When dissolved in water, will ionize into positively charged hydrogen ions (H+) & negatively charged ions of some other element or more simply yields hydrogen ions (H+) in solution Presence of H+ that gives a Sour taste Litmus paper testing (blue turns red)

Pages 22 – 23 Bases Base (alkali) = When dissolved in water, will ionize into negatively charged hydroxide (OH-) & positively charged ions of a metal Have a bitter taste & feel slippery between fingers Litmus paper testing (red turns blue)

Neutralization & Salts Page 23 Neutralization & Salts Neutralization (Exchange reaction) = when an acid & a base are combined, they form salt & water. Acid + Base = salt + water HCL + NaOH = NaCL + H2O

pH Scale Page 23 Measure of acidity or alkalinity (basicity) Ranges from 0 to 14 pH of 7.0 = neutral pH 0-6.9 = acid pH 7.1-14 = alkaline (basic)

Page 23 Homeostasis Homeostasis is essential for living cells to function optimally buffer = a compound that maintains pH balanced (example: NaHCO3) pH of blood is 7.35–7.45 Intracellular = fluid within the cell Extracellular fluids = fluid that bathes the cell & transports nutrients into & out of the cell (examples: blood, lymph, & interstitial fluid)