Unit 1 Review Answers PDF

Topic 1.1: Structure of Water and Hydrogen Bonding 1. Describe the structure of water that gives it its unique properties. Water is a polar compound where hydrogen and oxygen do not evenly share electrons (oxygen has a higher electronegativity and pulls electrons close). This gives ox...

Topic 1.1: Structure of Water and Hydrogen Bonding 1. Describe the structure of water that gives it its unique properties. Water is a polar compound where hydrogen and oxygen do not evenly share electrons (oxygen has a higher electronegativity and pulls electrons close). This gives oxygen a partial NEGATIVE charge and hydrogen a partial POSITIVE charge. 2. What is the difference between hydrogen bonding, ionic bonding, and covalent bonding? Hydrogen bonding is a weak interaction between polar compounds. Ionic bonding occurs to make a compound and is a transfer of electrons from a metal to a nonmetal (or sometimes polyatomic ions). Covalent bonding occurs to make a compound and is a sharing of electrons. 3. What types of compounds are hydrophobic? Hydrophilic? Compounds with a lot of C-H bonds or compounds that are evenly distributed (non-polar) are hydrophobic, whereas ionic compounds and polar compounds are hydrophilic. 4. What are the unique properties of water, and how does hydrogen bonding relate to all of them? High Specific Heat - More heat to change temp, as some heat breaks hydrogen bonds rather than increasing kinetic energy. Cohesion - water sticks to water, hydrogen bonding. Adhesion - water sticks to other polar substance, hydrogen bonding. High Heat of Vaporization - more heat to change from liquid to gas, as hydrogen bonds constantly reform More dense as liquid - when at a lower temperature, hydrogen bonding spreads water molecules out to form a lattice structure Evaporative cooling (see high heat of vaporization), water absorbs heat to vaporize, cooling organisms Surface tension (see cohesion), water molecules held together tightly at surface, requiring force to break H-bonds. Topic 1.2: Elements of Life 1. What are the elements that are necessary for life? CHONPS 2. Where do organisms obtain these elements? Depends. Plants get C and O from the air, H and O from water, and the others from the soil. Animals and fungi get O from air, H and O from water, and all others from food. Bacteria vary, as some can get C from air, but most are similar to animals. 3. What macromolecules use each element? Carbs- CHO Lipids- CHO (phospholipids have P) Protein- CHON and some S Nucleic acid- CHONP Topic 1.3: Introduction to Biological Macromolecules 1. What is dehydration synthesis? What is it used for, and for which monomers? Dehydration synthesis is the removal of -H from one monomer and -OH from another. A bond is then formed at that location between the monomers and water is removed. It is used to join all monomers (or to add a monomer to a polymer). 2. What is hydrolysis? What is it used for and for which polymers? It is basically the reverse of dehydration synthesis. A bond is broken between monomers (or two sections of a polymer) and -H is added to one and -OH is added to the other, resulting in two molecules. Topic 1.4: Properties of Biological Macromolecules 1. What are the monomers of Nucleic Acids? What three things do they consist of? Nucleotides, consisting of a phosphate group, a 5 carbon sugar (deoxyribose or ribose), and a nitrogenous base (Adenine and Guanine-Purines, Cytosine and Thymine/Uracil- Pyrimidines) 2. What are the monomers of Proteins? What three major groups do they consist of? Why are the characteristics of the R groups important? Amino acids, consisting of an amine group, a carboxyl group, and a central carbon with an R-group. R groups can be hydrophilic, hydrophobic, or ionic, and these help determine tertiary structure. 3. What are the monomers of Carbohydrates? How can you identify them? Monosaccharides, which have C, H, and O in a 1:2:1 ratio (roughly). 4. What are the monomers of Lipids? How does saturation/unsaturation affect a lipid? How is a phospholipid different than other lipids? Lipids are generally made of fatty acids and glycerol, though cholesterol doesn’t fit this. Saturated lipids are less fluid and pack tightly together due to straight chains of carbon and hydrogen. Unsaturated lipids are more fluid, as they have double bonds which create a solid bend in the chain, preventing tight packing. Phospholipids have a polar phosphate head, meaning they have a polar section and a non-polar section (other lipids are non-polar). Topic 1.5: Structure and Function of Biological Macromolecules 1. What is the basic structure of a DNA molecule? What pairs with what (NOTE HOW MANY HYDROGEN BONDS, this indicates strength)? What does the term anti-parallel mean? Usually, DNA exists as a double stranded molecule where the strands are arranged anti-parallel (if you examine the sugar-phospate backbone, imagine the sugar has a bottom and the phospate group is the top, one side starts with the sugar group and proceeds down, phosphate group binding to sugar, and the strand ends in a phosphate group. On the opposite side, the start is a phosphate group and it ends with the bottom of a sugar molecule). The  outer portion of the double strand is the sugar-phospate backbone, and the inner portion is the nitrogenous base pairing (A to T, G to C). 2. What is the type of bond formed between amino acids in proteins called? Is it a covalent, ionic, or hydrogen bond? Peptide bond, and it’s covalent between Nitrogen and Carbon. 3. What determines the primary, secondary, tertiary, and quaternary structure of a protein? Primary: Sequence of amino acids Secondary: As the protein starts to fold, the main chain of the polypeptide (H-N-C-C=O) begins to form hydrogen bonding between nearby folds (C=O:::H-N where ::: is hydrogen bonding). This forms helices (alpha) and sheets (beta). Tertiary: Interactions between R groups upon further folding. Hydrophobic regions clump together inside the protein, hydrophilic regions face the outside, ionic regions attract (+ to -) and sulfur containing regions can form covalent disulfide bonds. Quaternary: Multiple proteins forming together, sometimes with covalent bonds, sometimes with hydrogen bonding. 4. What interactions/bonds within DNA and Proteins does a change of pH and heat impact? How might this impact the macromolecule’s structure? Hydrogen bonding. Hydrogen bonding is a weak attractive force, so when these molecules are heated, the bonds break. When pH changes, the increased H+ or OH- will disrupt the hydrogen bonding attraction. This causes denaturation, so the molecule begins to lose its structure and cannot function. 5. What are the two main ways that carbohydrate monomers can be joined? In chains (like cellulose) or branched chains (like glycogen). Topic 1.6: Nucleic Acids 1. What is on the outside of a DNA double strand? What is on the inside? Already answered in previous section (Sugar Phosphate backbone outside, nitrogenous basepairs inside) 2. How does DNA differ from RNA? DNA is usually double stranded, RNA is usually single stranded. DNA has deoxyribose sugar, RNA has ribose. DNA has A, T, G, C, RNA replaces T with U. In double stranded DNA, A and T numbers are the same, as are G and C. In single stranded RNA, the number of A, U, G, C is independent.