Biology 107 Week 2 Study Guide Instructor_ Y. Vega.docx

**[Biology 107 Week 1 Study Guide Instructor: Y. Vega]** **[General Chemistry]** Understand the terms Atomic \# & Atomic mass (weight) Know the information presented on subatomic particles: protons, neutrons, electrons, and how to determine the number of each in an atom Know how electrons fill e...

**[Biology 107 Week 1 Study Guide Instructor: Y. Vega]** **[General Chemistry]** Understand the terms Atomic \# & Atomic mass (weight) Know the information presented on subatomic particles: protons, neutrons, electrons, and how to determine the number of each in an atom Know how electrons fill electron shells, know the terms valence electrons, valence shell and octet rule Know how to recognize chemical symbols for the biologically significant elements Know how to calculate the number of each atom in a compound or molecule Know the Law of Conservation of Matter (same as Conservation of Mass, Conservation of Atoms) Know how to determine the reactants and the products in a chemical reaction and the direction the reaction is proceeding Know how to sketch the electron configuration diagram for an atom and a molecule 1.) What is the difference between an atom, ion and isotope? 2.) What is a covalent bond? A polar covalent bond? 3.) Define hydrogen bonding. Give an example of why it is important in biochemistry. **[Covalent bonds]** are very strong chemical bonds and a source of potential energy. When we eat food the energy we obtain from the food comes from the covalent bonds of the food molecules. When we break the covalent bonds the stored energy is released. It requires energy to break these bonds so enzymes are required to lower the amount of energy required. Enzymes are proteins. Proteins function in a narrow range of pH and temperature. Any drastic changes to pH or temperature will denature the protein (change the 3-D shape). Know that Carbon can form 4 covalent bonds due to having 4 electrons in the valence shell. Know that an atom cannot gain or lose more than 3 electrons, so everything in column 4 (including Carbon) can only share electrons to complete the outer electron shell. Know the difference between the 2 types of covalent bonds: non-polar covalent bonds and polar covalent bonds **[Ionic bonds]: Know what causes ions to form**, Know how to determine the number of electrons in an ion and the net charge of the ion. Know the terms cation and anion. Know that ions are called electrolytes in your body. Know that an atom cannot gain or lose more than 3 electrons, so everything in column 4 can only share electrons to complete the outer electron shell. **[Electronegativity]**: Understand how electronegativity "sets the stage" for hydrogen bonding between water molecules. Understand that it is the DIFFERENCE IN ELECTRONEGATIVITY between the two atoms that determines whether electrons are shared equally or unequally in a covalent bond. If two atoms have the same or similar electronegativity they will share the electrons equally in a covalent bond (non-polar covalent bond). If there is a big difference in electronegativity between the two atoms, one will have a much stronger pull on those shared electrons and they will share unequally (polar covalent bond). **[Hydrogen bonds]**: Be able to explain how and why Hydrogen bonds occur. Be able to explain the role of electronegativity in Hydrogen bonding between water molecules. Know examples of where hydrogen bonds occur: water, DNA, proteins -Water dissociates into ions: [acid/base chemistry] Know the pH scale and what defines an acid, what defines a base Know that HCl is a strong acid (pH 1-2) and NaOH is a strong base (pH 14) Know the pH of blood (7.35-7.45) Know the role of buffers in the body Know the general equation for the carbonic acid buffer system and the basics of how it works. Know what happens to proteins when pH changes in the body Know the basics of how enzymes work and what happens if enzymes are denatured Know that shape is key! The body recognizes the shape of molecules Understand that pH is not the same throughout the body Understand the digestive system story from lecture, the significance of pH changes on enzyme activity, what regulates food moving into the small intestine, why we can't just have all the food from the stomach go into the small intestine at the same time.