CHEMISTRY OF LIFE Chapter 2

Levels of Chemical Organization Matter – anything that occupies space and has mass Molecules – particles of matter made up of atoms Atoms – protons, neutrons, electrons

A Model Of The Atom

Atomic number is equal to the number of protons Atomic mass is equal to the number of protons plus neutrons

Isotopes Same atomic number but different atomic mass

Compounds

CHEMICAL BONDING Ionic bond – strong electrical attraction between ions that bare opposite electrical charges - ionic molecules dissolve easily in water (dissociate) Covalent bond – bond formed between two atoms that share a pair of electrons

Ionic Bond https://www.youtube.com/watch?v=lODqdhxDtHM

Covalent Bond https://www.youtube.com/watch?v=j1e-f1W-0UA

Polar vs. Nonpolar Covalent Bonds Polar Covalent Bond – electrons are not shared equally (ex. H2O) Non Polar Covalent Bond – electrons are shared equally (ex. C-H)

Polar Covalent Bond

Hydrogen Bonding Hydrogen Bond – a weak electrical attraction between the partial positive charge of one water molecule and the partial negative charge of another water molecule

Inorganic Chemistry Molecules that generally do not contain carbon; there are no C-H or C-C bonds; smaller than organic molecules H2O is an inorganic molecule – “universal solvent” Organisms are composed mainly of water

Dehydration Synthesis – chemical reaction in which 2 molecules become covalently bonded by removing –H from one and –OH from another, removed atoms form water

Hydrolysis – the breaking apart of a molecule into its monomer subunits by the addition of the components of a H2O molecule into each of the covalent bonds linking the monomers

Acids, Bases & Salts Acid – a substance that releases H+ (hydrogen ions); pH<7 Base (alkaline) – a substance that releases OH- (hydroxide ions) or decreases H+ ; pH>7 Salt – substance composed of positively charged ions (not H+ ) and negatively charged ions (not OH-); usually neutral Buffers – substances that react with strong acid or base to keep pH constant by absorbing or releasing H+ or OH- as needed; helps to maintain homeostasis

pH Scale

Ketoacidosis/Alkalosis Ketoacidosis: A feature of uncontrolled diabetes mellitus characterized by a combination of ketosis and acidosis. Ketosis is the accumulation of substances called keytones and ketone bodies in the blood. Acidosis is increased acidity of the blood Alkalosis: A state characterized by a decrease in the hydrogen ion concentration of arterial blood. The condition may be caused by an increase in the concentration of alkaline compounds, or by a decrease in the concentration of acidic compounds or carbon dioxide.

Organic Chemistry Molecules contain H-C & C-C bonds Carbohydrates – carbon + water glycogen – animals store energy in this carb. Starch – plants store energy in this carb.

Phospholipids – major component of cell membranes Lipids – fats, oils and waxes – non polar, therefore they do not dissolve appreciably in water Phospholipids – major component of cell membranes Triglycerides – energy storage Cholesterol – steroid lipid – component of cell membrane; precursor to steroid hormones

Phospholipid Triglyceride

Enzyme – protein that acts as a catalyst Proteins - most varied of all the organic molecules in function; enzymes, structural, hormones, immunological, membrane components – building blocks are amino acids Enzyme – protein that acts as a catalyst Co-enzyme – some enzymes don’t function unless a co-enzyme is present (vitamins may serve this function)

Nucleic Acids – DNA and RNA (genetic material)

ATP – a modified nucleotide The role of ATP is to transfer energy from nutrient molecules to cellular processes