Basic Biochemistry Review

Basic Biochemistry Review (W17) Use the figure below to answer the following questions: 1. Name the 3 molecules illustrated in the figure. Carbon, Hydrogen and Oxygen. OH – Alcohol functional group is present as well 2. How many bonds are typically formed by each of the following atoms? Carbon - 4 Hydrogen - 1 Oxygen – 2 3. Symbols or atoms of what element(s) are missing from the line drawing? Symbols or atoms of Carbon and hydrogen are missing from the line drawing. 4. Given the line drawing of the molecule below, 1) draw the same molecule filling in the missing atoms (e.g., Lewis structure), and 2) write its molecular formula. O CH 3 OH 1 O H H H C C C C OH H H H H Molecular formula – C3H7COOH (Propanoic acid) Use the figure below (Properties of Biological Molecules) to answer the following questions: 2 1. In general, the presence of which elements makes a molecule polar? Based on the above data the presence of oxygen and nitrogen generally makes a molecule polar 2. What property do atoms of these elements have that helps make the molecules they are in polar? The atoms are firstly double bonded in a higher amount and possess highly electronegative atoms which tend to attract electrons more strongly in a covalent bond which helps make them polar 3. Can nonpolar molecules also have atoms of these elements? If yes, what distinguishes a nonpolar molecule from a polar molecule? Nonpolar molecules can also have atoms of these elements but the distinguishing factor is the number of oxygen and nitrogen atoms when compared to the carbon atoms in nonpolar molecules 4. In chemistry there is a saying “like dissolves like,” which means things will mix with or dissolve into each other best when their polarities are similar. a. Is water polar or nonpolar? – polar b. Is oil polar or nonpolar? – nonpolar c. Which of the substances above would dissolve well in water? Why? Water will dissolve well as their polarities are similar. d. Which of the substances above would dissolve well in oil? Why? Oil will dissolve well as their polarities are similar. e. Which of the above classes of substances, polar or nonpolar, is most likely to be found in higher concentration in the blood stream of vertebrates? Why? Polar as our body is 70% water and as water is polar it would be most likely to find that class of substance in higher concentrations in the blood stream. 5. What is another term for a polar molecule? What is the literal translation for this term? Hydrophilic. It means water loving. 3 6. What is another term for a nonpolar molecule? What is the literal translation for this term? Hydrophobic. It means water fearing. 7. Functional Groups are key groups of atoms in biological molecules. Both of the acidic molecules above have a carboxyl group. What is a carboxyl group? A carboxyl group is a functional acidic group with a full form of carboxylic acid which comprises of a carbon bonded doubly to an oxygen atom and singly to a hydroxyl group. 8. Recall the definition of an acid that you learned in chemistry. Explain how the reaction below illustrates the acidic properties of lactic acid. Bronsted lowry acids are proton donors and as visible in the above reaction Lactic acid donates a proton (H+ atom) and gains a negative charge due to more number of electrons than protons and releases H3O+ as a product after reacting with water which justifies its an acid. 9. Functional Groups are key groups of atoms in biological molecules. Both of the basic molecules above have an amine group. What is an amine group? Amine groups are functional groups that comprise of a nitrogen atom and 2 hydrogen atoms covalently bonded together. 10. Recall the definition of a base that you learned in chemistry. Explain how the reaction below illustrates the basic properties of adrenaline. 4 Bronsted lowry bases are compounds that accept a proton from a donator compound and as visible in the above reaction Nitrogen accepts an electron from H2O and gains a positive charge while reacting with water and giving out OH- as a product which justifies it’s a base. 11. Using the figure on page 2, predict the pH (pH = 7, pH < 7, or pH > 7) of a fairly concentrated aqueous solution. Lactic acid – pH < 7 Lactose – pH = 7 Dopamine – pH > 7 Amino acid – pH = 7 12. In chemistry you learned that covalent bonds are one type of intramolecular bond. They occur between nonmetal atoms in a molecule. You may have also learned about a type of intermolecular bond called a hydrogen bond. Hydrogen bonds are weak attractive forces between polar molecules containing strong polar bonds such as H-O, H-N or H-F. a. In the figure above, on the LEFT, how many different molecules are shown? i. Circle the carboxyl group ii. Put a square around the amine group b. In the figure on the RIGHT, 1) label at least two covalent bonds, and 2) label at least two hydrogen bonds. (Blue circle = hydrogen bonds) and (Red circle = covalent bonds) 5 13. Which of the molecules on page 2 would form hydrogen bonds with itself (other molecules of the same type) or with water molecules if in solution? Valine, Lactic acid and fatty acids when with water in a solution. 14. Although amino acids have “acid” in their name, some are acidic in water solutions, some are basic, and others are neutral. Propose an explanation for this observation based on the structures and descriptions of the amino acids below. These types of molecules are called amphiprotic species which change their nature of being an acid, base or neutral based on different reactions. It’s due to the molecules possessing the 15. The pH of a 5-Hour Energy drink is 3. a. What is the hydrogen ion concentration? = 0.001 moldm-3 b. Write the hydrogen ion concentration as a decimal. = 2.85 c. What is the hydroxide ion concentration? = 10-11 d. Write the hydroxide ion concentration as a decimal = 0.00000000001 moldm-3 16. An Unknown Solution has a pH of 6. 6 a. What is the hydrogen ion concentration of the Unknown Solution? – 10-6 moldm-3 b. Write the hydrogen ion concentration as a decimal. – 0.000001 moldm-3 17. Which decimal is bigger, H+ concentration of the 5-Hour Energy drink (15b) OR the unknown solution (16b)? The decimal of the 5-Hour energy drink is bigger than the unknown solution. 18. How many times more acidic is the 5-Hour Energy drink than the Unknown Solution? It is 103 times acidic 7