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Chapter 2 THE CHEMISTRY OF LIFE © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Introduction • Cells, tissues and organs composed of chemicals • Chemical reactions important for function • Chemistry is the study of: – Elements, compounds, chemical reactions, molecular structure © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. ATOMIC STRUCTURE © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Atomic Structure (cont’d.) • Atoms – Smallest particles of elements – Maintain all characteristics of element – Nucleus contains protons and neutrons – Electrons orbit nucleus in shells © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. ELEMENTS, ISOTOPES, COMPOUNDS © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Elements, Isotopes, Compounds (cont’d.) • Element: atoms contain same numbers of protons and electrons • Compound: contains two or more elements • Isotope: number of neutrons varies • Periodic table of the elements – Arranges elements by increasing atomic number © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Elements, Isotopes, Compounds (cont’d.) • Orbital: area where electron is found • Energy levels: grouping of orbitals – Represented as concentric circles surrounding nucleus © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. BONDS AND ENERGY © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Bonds and Energy (cont’d.) • Ionic: one atom gains and one atom loses electrons • Covalent: atoms share electrons • Hydrogen: weak bonds, hold water molecules together • Electron donors vs. acceptors vs. carriers • Bonds are energy containing © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Bonds and Energy (cont’d.) © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Bonds and Energy (cont’d.) © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. COMMON SUBSTANCES IN LIVING SYSTEMS © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Water • • • • • Most abundant substance in cells Universal solvent Transport of materials Absorbs and reduces heat Protects body structures © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Carbon Dioxide • Waste product of cellular respiration • Used in photosynthesis to produce usable energy sources • Must be removed quickly from cells • Carbon in molecules comes from carbon dioxide gas © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Molecular Oxygen • Formed from covalent bond of two oxygen atoms • Required by all organisms that breathe air • Necessary to convert food into ATP • Level in atmosphere is 21% © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Ammonia • By-product of amino acid breakdown – Amino acids are building blocks of proteins – Amino acids contain nitrogen • Converted to urea in the liver © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Mineral Salts • Composed of small ions • Calcium: muscle contraction and strong bones • Phosphate - ATP synthesis • Sodium, potassium, and chloride are necessary for muscle contraction and nervous transmission © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Carbohydrates • 1:2:1 ratio of carbon, hydrogen and oxygen • Five- and six-carbon simple sugars are smallest – Five-carbon: deoxyribose and ribose – Six-carbon: glucose and fructose • Functions: energy storage and cell structure © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Lipids • Insoluble in water • 95% of fats in body are triacylglycerols • Saturated fat: fatty acids have single covalent bonds • Unsaturated fat: fatty acids have one or more double covalent bonds • Functions: energy, insulation and protection © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Proteins • Contain carbon, oxygen, hydrogen, nitrogen and sulfur • Amino acids are building blocks of proteins • Functions: energy and structure • Enzymes: protein catalysts for chemical reactions © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Proteins (cont’d.) • Structure – Primary: amino acid sequence – Secondary: determined by hydrogen bonds – Tertiary: folding caused by interactions within peptide bonds and sulfur atoms – Quaternary: determined by spatial relationships between units © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Nucleic Acids • Deoxyribonucleic acid: genetic material of the cell • Ribonucleic acid: protein synthesis – Messenger RNA – Transfer RNA © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Nucleic Acids (cont’d.) • Structure – DNA: double helical chain – RNA: single chain © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Nucleic Acids (cont’d.) • Nucleic acids are made up of chains of nucleotides – Nucleotide: nitrogen base, sugar and phosphate group – Nitrogen bases: purines (two) and pyrimidines (three) © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Adenosine Triphosphate • Fuel for cell function and maintenance • Molecule consists of sugar, adenine, and three phosphates – Energy is stored in the second and third phosphates • Breakdown of glucose provides energy to make ATP © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. MOVEMENT OF MATERIALS INTO AND OUT OF CELLS © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Introduction • Plasma membrane is selectively permeable – Only selected materials can enter and exit – This is because of chemical structure – Water can enter and exit with ease © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Diffusion • Movement of molecules from area of high concentration to low concentration • Brownian movement: random collision of diffusing molecules • Accelerated by increased temperature • O2 - CO2 exchange is an example of diffusion © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Osmosis • Movement of water through semipermeable membrane from high concentration to low concentration – Isotonic solution: salt concentration is the same outside the cell as inside – Hypotonic solution: salt concentration inside cell is higher than outside cell © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Osmosis • Movement of water through semipermeable membrane from high concentration to low concentration – Hypertonic solution: salt concentration higher outside the cell than inside © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Osmosis (cont’d.) © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Osmosis (cont’d.) • Active transport – Used by cells to obtain sugars, amino acids, larger proteins and fats – Needs energy in the form of ATP – Molecules move from areas of low concentration to areas of high concentration © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. pH © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. pH (cont’d.) • Negative logarithm of hydrogen ion concentration • Acids: pH values below 7 • Bases: pH values above 7 • Buffers: help maintain pH levels © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. pH (cont’d.) © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Summary • Discussed basic chemical concepts such as bonds and energy and how they apply to living systems • Discussed specific chemical substances and how they are used in living systems © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Summary (cont’d.) • Described three ways that substances move into and out of cells • Introduced pH and acids/bases © 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.