Chemistry of Life

Objectives Define the terms atom, element, molecule, and compound. Describe the structure of an atom. Compare and contrast ionic and covalent types of chemical bonding. Distinguish between organic and inorganic chemical compounds.

Objectives Discuss the chemical characteristics of water. Explain the concept of PH. Discuss the structure and function of the following types of organic molecules: Carbs Lipids Proteins Nucleic acid

Levels of Chemical Organization Matter Anything that occupies space and has mass. Molecules are particles of matter, made up of atoms.

Atoms Nucleus Central core of the atom Contains subatomic particles: Protons = positively charged Number of protons determines type of atom. (atomic number) Neutrons = no charge

Atoms Orbiting around the nucleus are negatively charged particles called electrons. Energy levels (shells) Outer level may hold up to 8 electrons. Energy increases with distance from the nucleus. Number of electrons in the outer shell affects the atoms ability to unite with other atoms.

Elements, Molecules, and Compounds Pure substance; made up of only one kind of atom. Molecule Group of atoms bound together. Compound Substances whose molecules have more than one kind of atom.

Elements, Molecules, and Compounds Compounds are written in formulas containing symbols and number of atoms in subscript. Example: Carbon Dioxide CO2

Elements, Molecules, and Compounds Four kinds of atoms make up approx. 96% of the human body. Oxygen Carbon Hydrogen Nitrogen 20 or more trace elements.

Chemical Bonding Chemical bonds form to make atoms more stable. Considered stable when the outer energy level is full. (8 electrons) Atoms will share, donate, or borrow electrons to fill the outermost energy level.

Ionic Bonds Ions form when atoms gain or lose electrons in the outer energy levels. Positive Ions Have lost electrons becoming positively charged. Negative Ions Have gained electrons becoming negatively charged.

Ionic Bonds Example: (Fig 2-2) Sodium – Na Containing 1 electron in outer shell. Chlorine – Cl Contains 7 electrons in outer shell. Donating or borrowing electrons make sodium positively charged and chlorine negatively charged forming a bond NaCl or Sodium Cloride.

Electrolytes Ionic molecules dissociate easily in water forming electrolytes. Examples: Sodium – Na+ Chloride – Cl- Calcium – Ca++ Potassium – K+

Covalent Bonds Atoms that share electrons, rather than donate or receive them form covalent bonds. Bonds are not easily broken and do not break apart in water.

Organic/Inorganic Compounds Living organisms contain both organic and inorganic compounds. Organic compounds contain: Carbon to Carbon covalent bonds And/Or Carbon to Hydrogen covalent bonds Inorganic compounds lack these bonds.

Inorganic Compounds Water Most abundant compound in the body. Solvent that other solutes are dissolved. Aqueous solution Essential in many important chemical reactions.

Chemical Reactions Fig 2-4 Dehydration synthesis Water is removed from smaller molecules so larger ones can be created. Hydrolysis Water is added to larger molecules to break them apart into smaller ones.

Chemical Reactions Chemical reactions involve energy transfers. Some of the energy used to build the molecules are stored as potential energy and released when broken apart. Example: Adenosine Triphosphate (ATP) Needed for muscle contraction.

Chemical Reactions Chemical equations show how reactants interact to form products. Written with “arrows” to separate and show products. Example: K+ + Cl- KCL

The pH Scale

Acids, Bases, and Salts Water molecules dissociate to form equal amounts of Hydrogen Ions/Hydroxide Ions. Neutral pH 7.0 Acids are higher in Hydrogen Ions (< 7.0) Bases/Alkalines are lower in Hydrogen Ions (>7.0)

Acids, Bases, and Salts Strong acids or strong bases are neutralized when mixed with each other and form salts. Buffers are chemical systems that absorb excess acids or bases and thus maintain a relatively stable pH.

Organic Compounds More complex than inorganic compounds. Carbohydrates Lipids Proteins Nucleic acids

Organic Compounds Carbohydrates Sugars and complex carbohydrates Monosaccharide (Glucose/Dextrose) Disaccharide (Sucrose/Lactose) Polysaccharides (Glycogen/Starches) Contains Carbon, Hydrogen, Oxygen Uses for energy or stores for later use.

Organic Compounds Lipids - Fats and oils Triglycerides Glycerol and 3 fatty acids. Stores energy. Phospholipids Phosphorus unit with 2 fatty acids Forms cell membranes Cholesterol Transports lipids Basis for making steroid hormones

Organic Compounds Proteins Very large molecules composed of amino acids held together in long folded chains by peptide bonds. Structural proteins Functional proteins Can bond with other compounds to form mixed molecules: Glycoproteins Lipoproteins

Organic Compounds Structural Proteins Form structures in the body. Collagen is a fibrous protein that holds many tissues together. Keratin forms tough, waterproof fibers in the outer layer of the skin.

Organic Compounds Functional Proteins Participate in chemical processes. Examples: Hormones Cell membrane channels/receptors Enzymes

Organic Compounds Enzymes Catalysts Assist with chemical reactions Lock and Key model Each enzyme fits a particular molecule that it acts on as a key fits into a lock.

Organic Compounds Nucleic acids Direct proteins for overall body structure and function. Basic building blocks are called nucleotides. Phosphate, sugar, and nitrogen base. Deoxyribonucleic Acid (DNA) Ribonucleic Acid (RNA)

Nucleic Acids Deoxyribonucleic Acid (DNA) Nucleotide bases: Adensine Thymine Guanine Cytosine Used as a master code for assembling proteins.

Nucleic Acids Ribonucleic Acid (RNA) Nucleotide bases: Adensine Uracil Guanine Cytosine Used as a temporary working copy of a gene. Portion of DNA code

Are you as confused as I am? Any Questions?