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BIOCHEMISTRY CHEMISTRY OF LIFE In Biology, we deal mostly with elements within the elements within the first 4 rows (periods) of the Periodic Table. Bulk Elements: C, H, O, N – make up the majority of every living thing. •Ex. 96% of human body Minerals: •Ma, Mg, P, K, Ca (3.5%) •Fe, I (trace elements – tiny amounts) CHEMISTRY OF LIFE Therefore, Biochemistry means the “chemistry of life” Recall basic atomic structures:  atoms consist of a dense positive nucleus surrounded by orbiting electrons  compounds are created when valence electrons are transferred or shared  chemical bonds can be divided into two large categories: between atoms  Ionic  Covalent IONS An atom is able to gain or lose electrons When this happens, it is known as an ion There are 2 types of chemical bonds IONIC and COVALENT 1. Ionic Bonding - one atom donates an electron to another atom positive ion (lost electrons) negative ion (gained electrons) 2. Covalent Bonding - involves sharing electrons between atoms CHEMICAL BONDING Electrons move around the atomic nucleus at a distance determined by the amount of energy the electron has Electrons in the outermost orbital are called valence electrons Valence electrons determine the chemical behaviour of an atom ISOTOPES Dalton was wrong. Atoms of the same element can have different numbers of neutrons different mass numbers called isotopes C-12 vs. C-14 California WEB ISOTOPES Electrons Nucleus Neutron Proton Proton + + + + + + Nucleus Carbon-12 Neutrons 6 6 Protons Electrons 6 Nucleus + + Neutron + + + + Electrons Carbon-14 Neutrons 8 6 Protons Electrons 6 Nucleus RADIOISOTOPE Radioisotope is an unstable isotope that decays over time by emitting radiation. • Carbon-12 and carbon-13 are stable isotopes of carbon, but carbon-14 is radioactive--it spontaneously decays into nitrogen-14. ORGANIC MOLECULES Many of the chemicals that a cell uses or produces are organic molecules contain carbon and hydrogen strung together in chains these molecules should not dissolve in water because the bonds between C and H are almost purely covalent INTERACTIONS WITHIN MOLECULES Ionic and covalent bonds are generally called intramolecular forces of attraction because they hold the atoms of a molecule or ions of an ionic solid together “Intra” means “within” Electronegativity is a measure of an atom’s ability to attract a shared electron pair when it is participating in a covalent bond The larger the electronegativity number, the stronger the atom attracts the electrons of a covalent bond INTERACTIONS BETWEEN MOLECULES Forces between molecules are called intermolecular forces (“inter” means “between”) This type of force (bond) can be formed between different molecules or between different parts of the same molecule if the molecule is quite large Intermolecular interactions are much weaker than intramolecular interactions A UNIVERSAL SOLVENT Water is known as the universal solvent because is dissolves many substances Substances are divided into two categories based on whether or not they dissolve WATER IS ESSENTIAL TO LIVING SYSTEMS Water is made up of polar molecules meaning that the water molecule has one end with a slight negative charge and one end with a slight positive charge. -ve +ve “Hydrogen Bonding” HYDROPHILIC SUBSTANCES ‘Hydrophilic’ means “water-loving” Dissolve well in water  Ex. Sugar, salt These substances are made of polar molecules or ions  Ex. Sugar (sucrose) and table salt HYDROPHOBIC SUBSTANCES ‘hydrophobic’ means “water-fearing” Does not dissolve well in water Dissolve well in other hydrophobic substances  Ex. Vitamins ADEK – fat soluble Hydrophobic materials often protect against water With hydrocarbons, other elements such as hydrogen, oxygen, sulfur, and phosphorus may attach to the carbon backbone to form reactive clusters of atoms called functional groups Functional groups possess certain chemical properties that they impart to the molecules to which they are attached. These groups are more reactive than the hydrocarbon portions of biological molecules. Most of the reactions that occur in living organisms involve functional group interactions Table 1.1, pg 14 → know these groups! •Carbon compounds work the way they do because of their functional groups. •Functional groups are usually the part involved in reactions. •Functional groups have constant properties, and there are six that concern us. HYDROXIDE GROUP Properties: These are the alcohols. They absorb hydrogen ions = BASIC. OH- + H+  H2O CARBOXYL GROUP Properties: Can donate Hydrogen ions = ACID Joins with amino groups to form peptide bonds in proteins AMINE GROUP Properties: These are the amines. Amines are found in all amino acids, and join with carboxyl groups to make protein chains. SULFHYDRYL Group Properties: These are the thiols. They help to form sulfur bridges in proteins, and thus help give shape to proteins. PHOSPHATE Group Properties: Due to symmetry and ‘rotating’ double bond, it is ideal for energy transfer reactions Cellular Respiration (creating ATP). Also found in the backbone of DNA and RNA. -R GROUP The –R group creates the diversity of amino acids Some -R groups are small, others large Some –R groups are hydrophobic, others hydrophilic The type of –R group directly affects the structure of the protein 1) HYDROXYL - OH Found in alcohols 2) CARBOXYL – COOH/COO- Found in acids Acetic Acid 3) AMINO – NH, NH2, NH3 + 4) SULFHYDRYL - SH 5) PHOSPHATE – PO4 3- 6) CARBONYL – CO/COH WHICH OF THE FOLLOWING CORRECTLY ILLUSTRATE A CARBOXYL GROUP? HOMEWORK Read Section 1.1 in text (pg 10-15) Q#1-5, pg 13 Q#1-9, 11-13, pg 17 Q#1-14, pg 4-5