THE CHEMICAL BASIS OF THE BODY

The Composition of Matter Matter- the stuff of life Atom- smallest unit of matter that has specific properties Molecules- combination of 2 or more atoms ex: H + H H2 Compounds- combination of 2 or more different atoms ex: H + H + O H20

Atomic Structure Nucleus Electron Shell Protons (+ charge) Neutrons (no charge) Electron Shell Electrons (negative charge)

Atomic Structure (Continued) Isotopes- atoms of the same element with different numbers of neutrons. Atomic Weight- average mass of an atom.

Chemical Bonds & Chemical Compounds Ionic Bonds-anions and cations are held together by the attraction of negative and positive charges. Covalent Bonds-atoms held together by the sharing of electrons. Hydrogen Bonds-attraction between hydrogen and a negatively charged particle.

3 Types of Chemical Reactions: Synthesis-chemically combining two molecules A+B AB Decomposition- breaking large molecules into smaller molecules AB A + B

Exchange Reactions- molecules are shuffled around. AB + CD AD + CB

Examples Synthesis- glycerol + 3 fatty acids -------> fat Decomposition- glucose -------> carbon dioxide + water Exchange Reaction- NaOH + HCl ---- NaCl + H2O

Reversible Reactions A + B ------- AB AB --------- A + B Na + OH -----NaOH HCl------ H + Cl

pH and Buffers pH-Concentration of hydrogen atoms Buffers-compounds that stabilize pH by removing or replacing hydrogen atoms.

Inorganic Compounds Inorganic compounds- do not contain carbon & hydrogen atoms together. They are held together by ionic bonds Examples: Water Salts Acids and Bases

Water Makes up 60-70 % of a cells mass Universal solvent Released by cells to reduce friction between body parts Important transport medium Has a high heat capacity

Acids & Bases Acid- molecule that releases one or more hydrogen ions when ionized in water ex: HCl is a strong acid Base- molecule that reduces a concentration of hydrogen ions in the solution ex: NaOH is a strong base

Organic Compounds- building blocks of most living structures Carbohydrates Lipids Proteins Nucleic Acids ATP

Carbohydrates Contain: C, H, O Sugars and starches Energy source to fuel body activities 3 types: Monosaccharides- simple sugars Ex: glucose, fructose, galactose Disaccharides- two monosaccharides fused together Ex: sucrose, lactose, maltose Polysaccharides- long chains of simple sugars chemically bonded together Ex: starch, glycogen

Lipids Composed of : carbon, hydrogen, and oxygen Fats, phospholipids, steroids

Fats Composed of 3 fatty acid chains and 1 glycerol 2 Types: Saturated fat- long fatty acid chains, single bonds, solid at room temperature Found in animal product (butter, meat) Unsaturated fat- short fatty acid tail, double bonds, liquid at room temperature Found in plants (cooking oils)

Phospholipids Composed of 2 fatty acid chains and a phosphorus group Component of cell membranes

Steroids In ring structures, not fatty acid chains They are chemicals that alter cell activity to maintain homeostasis Ex: Cholesterol- synthesized in liver, obtained from eggs, meat, and cheese

Protein Composed of carbon, hydrogen, oxygen, and nitrogen atoms (may contain sulfur & phosphorus atoms) Amino acids- building-block molecules for protein Peptide bond- covalent bond between 2 amino acids Polypeptide- a chain of more than ten amino acids Makes up to 10-30% mass of a cell

Nucleic Acids Contains carbon, hydrogen, oxygen, nitrogen and phosphorus Nucleotides- building blocks of nucleic acids 5-carbon sugar, phosphate group, nitrogenous base Holds information of a cells structure & function

DNA- deoxyribonucleic acid Nucleic acid that contains nucleotides with the five-carbon sugar deoxyribose 4 nitrogenous bases: - adenine - cytosine - thymine - guanine Nucleotides arranged in 2 strands twisted to form a double helix DNA contains hereditary material called genes

RNA – Ribonucleic Acid Contains the five carbon-sugar ribose Nucleotides are in a single strand Uracil instead of thymine

ATP- Adenosine triphosphate Nucleotide found in all living organisms Captures and stores energy within its bonds Similar to RNA but with 2 additional phosphate bonds (ribose group and a adenine base group) Cellular respiration- the break down of glucose molecules to provide energy