Comprehensive Study Guide on Organic Chemistry, Hydrocarbons, and Biomolecules

Chemical Bonds, Water Properties, and Exam Procedures

• Electronegativity and Nonpolar Bonds:

  • An electronegativity difference of $0.4$ defines a nonpolar covalent bond.
  • Nonpolar substances repulse water (hydrophobic behavior).

• Cohesion vs. Adhesion:

  • Cohesion refers to the attraction between similar molecules (e.g., water molecules holding onto other water molecules).
  • Metaphor: Water molecules playing Red Rover to maintain surface tension.
  • Example: A wasp sitting on the surface of water is supported by water's cohesive forces holding the liquid surface together. If the weight of the wasp exceeds the cohesive strength, the water molecules separate, and the wasp sinks into the water. The water molecules do not stick to the wasp; they hold onto each other.
  • Adhesion refers to the attraction between dissimilar molecules (sticking to a different substance).

Administrative Guidelines and Exam Monitoring Rules

• Respondus Monitor Protocol:

  • Following completion of an online exam, physical whiteboards used for scratch work must be wiped completely clean.
  • Purpose: Prevents unauthorized recording or distribution of exam questions.

• Academic Resources and Final Exam Recovery:

  • Calendar booking links attached to academic email signatures allow students to directly schedule online meetings that automatically flag calendar availability.
  • Low scores on early examinations can be mitigated by strong performance on the comprehensive final exam.
  • Support options include Supplemental Instruction (SI), tutoring services, and faculty consultations.

Hierarchy of Biological Organization and Organic Hydrocarbons

• Hierarchical Scale of Life:

  • Subatomic particles ($\text{protons}$, $\text{neutrons}$, $\text{electrons}$) $\rightarrow$ Atoms $\rightarrow$ Compounds and Molecules $\rightarrow$ Biomolecules ($\text{fats/lipids}$, $\text{proteins}$, $\text{nucleic acids}$, $\text{sugars/carbohydrates}$) $\rightarrow$ Cellular Organelles ($\text{nucleus}$, $\text{Golgi apparatus}$, $\text{endoplasmic reticulum}$) $\rightarrow$ Cells $\rightarrow$ Organisms ($\text{Biology}$).

• Hydrocarbon Characteristics:

  • Organic molecules are characterized by the presence of hydrocarbons.
  • Hydrocarbons consist exclusively or primarily of carbon and hydrogen atoms ($\text{C}$ and $\text{H}$).
  • Due to the minimal electronegativity difference between carbon and hydrogen, hydrocarbons are nonpolar.
  • Hydrocarbons serve as high-energy fuel sources capable of long-term energy storage.

• Nomenclature Prefixes Based on Carbon Chain Length:

  • Single covalent bonds between carbon atoms receive the suffix -ane.
  • $1$ Carbon ($\text{meth-}$): Methane ($\text{CH}_4$), a single-carbon flammable gas.
  • $2$ Carbons ($\text{eth-}$): Ethane ($\text{C}_2\text{H}_6$) and Ethanol ($\text{C}_2\text{H}_5\text{OH}$).
  • $3$ Carbons ($\text{prop-}$): Propane ($\text{C}_3\text{H}_8$); recall analogy of an airplane with 3 propellers.
  • $4$ Carbons ($\text{but-}$ / $\text{bute-}$): Butane ($\text{C}_4\text{H}_{10}$).
  • $5$ Carbons ($\text{pent-}$): Pentane ($\text{C}_5\text{H}_{12}$).
  • $6$ Carbons ($\text{hex-}$): Hexane ($\text{C}_6\text{H}_{14}$).
  • $7$ Carbons ($\text{hept-}$): Heptane ($\text{C}_7\text{H}_{16}$).
  • $8$ Carbons ($\text{oct-}$): Octane ($\text{C}_8\text{H}_{18}$).
  • $9$ Carbons ($\text{non-}$): Nonane ($\text{C}_9\text{H}_{20}$).
  • $10$ Carbons ($\text{dec-}$): Decane ($\text{C}_{10}\text{H}_{22}$).

Petroleum Fuel Refining, Engine Mechanics, and Functional Groups

• Gasoline Octane Ratings and Engine Physics:

  • Commercial gasoline fuel pumps offer octane ratings such as $87$, $89$, and $91$ octane.
  • Gasoline physically feels oily and forms nonpolar, insoluble layers on water puddles.
  • Octane ($\text{C}_8\text{H}_{18}$) is a long-chain hydrocarbon fat/fuel.
  • Internal combustion engines compress fuel-air mixtures before ignition by a spark plug to drive pistons.
  • High-performance, high-compression engines (e.g., turbocharged or supercharged engines in sports cars) require high octane ratings ($91$ octane) to prevent predetonation.
  • Predetonation occurs when lower-octane fuel spontaneously combusts under high compression before spark plug ignition, causing engine knock because the fuel lacks sufficient hydrocarbon chain length to resist premature compression ignition.

• Crude Oil Extraction and Refining:

  • Fuel pumps carry certification seals from the Department of Agriculture because petroleum originates from geological deposits inside the Earth.
  • Crude oil (black gold or Texas tea) is extracted via drilling from regions such as West Texas, the Gulf of Mexico, Venezuela, and the Middle East.
  • Extracted crude oil is transported via tankers to industrial refineries (such as those in Houston) where fractional distillation yields heavy grade fuel oils, diesel, asphalt, tar, motor oils, liquid fuel grades, and compressed natural gases (butane, propane, ethane, methane).
  • Fossil fuels represent ancient organic residues from compressed prehistoric plants and dinosaurs.

• Alteration of Chemical Functionality via Functional Groups:

  • Methane ($\text{CH}_4$): A flammable gas generated by organic decomposition in landfills and animal flatulence.
  • Adding a hydroxyl group ($-\text{OH}$) converts gaseous methane into liquid methanol ($\text{CH}_3\text{OH}$), a liquid top-fuel used in drag strip racing engines (e.g., nitromethane/methanol blends at speedways located 7 exits north on I-15 North).
  • Adding a hydroxyl group ($-\text{OH}$) to ethane forms liquid ethanol ($\text{C}_2\text{H}_5\text{OH}$), the alcohol present in consumable beverages.
  • Adding a hydroxyl group ($-\text{OH}$) to propane yields liquid propanol ($\text{C}_3\text{H}_7\text{OH}$), which is polar and water-soluble.
  • Compressed butane inside disposable gas station lighters exists as a liquid under pressure, but volatilizes into a gas immediately upon release of pressure.
  • Attaching carboxylic acid functional groups ($-\text{COOH}$ attached to an $\text{R}$ group) converts nonpolar hydrocarbons into polar or amphipathic molecules such as pentanaldehyde or fatty acids.

Elemental Composition and Mass Distribution of Organisms

• Elemental Definitions of Major Biomolecules:

  • Hydrocarbons: Contain Carbon and Hydrogen ($\text{C}, \text{H}$).
  • Sugars / Carbohydrates: Contain Carbon, Hydrogen, and Oxygen ($\text{C}, \text{H}, \text{O}$).
  • Proteins: Contain Carbon, Hydrogen, Oxygen, and Nitrogen ($\text{C}, \text{H}, \text{O}, \text{N}$); some contain Sulfur ($\text{S}$).
  • Nucleic Acids (DNA / RNA): Contain Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, and Sulfur ($\text{C}, \text{H}, \text{O}, \text{N}, \text{P}, \text{S}$).

• Organismal Water and Dry Mass Breakdown:

  • Living organisms consist of $60\%$ to $90\%$ water by weight (averaging approximately $70\%$ water mass).
  • Total body weight distribution: Approximately $75\%$ water weight and $25\%$ dry solid mass weight.
  • Electrolytes / Ions: Small inorganic ions like Iron ($\text{Fe}$ in hemoglobin) and Calcium ($\text{Ca}$ in bone matrices) constitute a tiny fraction of total weight. Soluble ions in excess are excreted via urine.
  • Dry solid mass distribution ($25\%$ of total body weight):
  • Protein: Constitutes over $50\%$ (approx. $55\%$) of dry mass, comprising muscle tissue, structural bone matrix, and organ connective tissues.
  • Nucleic Acids (DNA / RNA): Represents a measurable portion of dry mass (accounting for several pounds in a $100\,\text{lbs}$ organism).
  • Carbohydrates: Stored short/medium-term fuel in the liver and skeletal muscle groups.
  • Lipids: Stored long-term energy reserves throughout body adipose tissue.

• Chemical Transformation during Digestion:

  • Ingested dietary proteins (e.g., cow skeletal muscle steak or plant tofu) are chemically broken down during digestion into constituent amino acids.
  • The human body does not integrate foreign proteins directly; instead, it hydrolyzes dietary proteins and reassembles the free amino acids into human-specific proteins.

Polymer Dynamics, Hydrolysis, and Dehydration Synthesis

• Monomer and Polymer Definitions:

  • Monomer: A single chemical subunit (mono = one, mer = subunit), such as an individual glucose molecule.
  • Polymer: A large macromolecule composed of many linked subunits (poly = many, mer = subunit).

• Chemical Reactions for Cleavage and Synthesis:

  • Hydrolysis:
  • Etymology: hydro = water, lysis = to cut, break, or burst.
  • Process: Disassembly of polymers into individual monomers through the insertion of a water molecule ($\text{H}_2\text{O}$).
  • Mechanism: Water splits and cleaves the covalent bond joining two subunits. To fully digest a polymer held by $3$ covalent bonds, $3$ water molecules must be inserted.
  • Dehydration Synthesis:
  • Etymology: dehydrated = loss of water, synthesis = to create or make something original.
  • Process: Assembly of polymers from individual monomers through the removal of a water molecule ($\text{H}_2\text{O}$).
  • Mechanism: A hydroxyl group and a hydrogen atom are removed from adjacent monomers, forming water as a byproduct and creating a new covalent bond between the subunits.

Enzymes and Energetics of Activation

• Core Properties of Enzymes:

  1. Enzymes are specialized proteins.
  2. Enzymes act as catalysts that accelerate chemical reaction rates.
  3. Enzymes possess extreme specificity, performing one specific job.
  4. Enzymes lower the activation energy ($E_a$) required for chemical reactions.

• Activation Energy and Covalent Bond Formation:

  • Covalent bonds involve the sharing of valence electrons between nonmetal atoms.
  • Electron clouds carry negative charges; bringing two separate monomeric molecules together creates strong electrostatic repulsive forces between their electrons.
  • Activation Energy ($E_a$): The energy threshold required to overcome repulsive forces and facilitate bond formation or breakage.
  • Analogy for Catalysis: Dating applications (such as Tinder, Hinge, Bumble, or PlentyOfFish) serve as facilitators for bond formation, drastically reducing the effort and energy required for two individuals to establish a bond.
  • Analogy for Bond Cleavage: A gossip-spreading acquaintance who introduces interpersonal tension acts as an enzyme applying strain to weaken and sever a stable bond.

Classification and Physical Properties of Carbohydrates and Lipids

• Classifications across Biomolecule Families:

  • Carbohydrates: Monosaccharides (e.g., glucose, fructose) $\rightarrow$ Disaccharides (e.g., sucrose, lactose, maltose) $\rightarrow$ Polysaccharides (e.g., starch, glycogen, cellulose, chitin).
  • Lipids: Fatty acids and glycerol $\rightarrow$ Monoglycerides, Diglycerides, Triglycerides, Biological Membranes, Waxes, and Steroids.
  • Proteins: $20$ standard Amino Acids $\rightarrow$ Polypeptide chains and functional Proteins.
  • Nucleic Acids: Nucleotides ($\text{Adenine}$, $\text{Thymine}$, $\text{Cytosine}$, $\text{Guanine}$, $\text{Uracil}$) $\rightarrow$ DNA and RNA.
  • Adenosine Triphosphate (ATP): The universal cellular energy molecule generated by breaking down fats, proteins, and carbohydrates.

• Structural Modification of Hydrocarbons into Fatty Acids:

  • Modifying an octane molecule ($\text{C}_8\text{H}_{18}$) by removing two terminal hydrogens and bonding a carboxylic acid functional group ($-\text{COOH}$) yields a fatty acid molecule featuring a nonpolar hydrocarbon tail and a polar carboxylic acid head.

• Chemical Ratios and Molecular Weight Distinctions in Sugars:

  • Simple Monomeric Sugars:
  • Stoichiometric ratio: $\text{C}_n\text{H}_{2n}\text{O}_n$ or a $1:2:1$ ratio of $\text{C}:\text{H}:\text{O}$, where $n$ ranges from $3$ to $7$.
  • $n=3 \rightarrow \text{C}_3\text{H}_6\text{O}_3$
  • $n=4 \rightarrow \text{C}_4\text{H}_8\text{O}_4$
  • $n=5 \rightarrow \text{C}_5\text{H}_{10}\text{O}_5$
  • $n=6 \rightarrow \text{C}_6\text{H}_{12}\text{O}_6$ (Glucose)
  • $n=7 \rightarrow \text{C}_7\text{H}_{14}\text{O}_7$
  • Glucose possesses a low molar mass / molecular weight of $180.01\,\text{g/mol}$.
  • Properties of Low Molecular Weight Sugars: Sweet taste, highly soluble in water (e.g., sucrose/fructose in sports drinks like Gatorade).
  • Complex Polysaccharides:
  • Composed of extensive chains (e.g., $150$ or more glucose subunits linked together).
  • Molar mass calculation example: $150 \times 180.01\,\text{g/mol} = 27001.5\,\text{g/mol}$.
  • Properties of High Molecular Weight Carbohydrates: Tasteless, insoluble in water.
  • Examples: Paper fibers, wood products (medium-density fiberboard, plywood), cotton fabric clothing.

Plant and Animal Energy Storage Polysaccharides

• Thermal Hydrolysis of Polysaccharides:

  • Boiling or cooking starchy foods (such as rice or potatoes) supplies thermal energy to break long polysaccharide chains into simple monosaccharide units via hydrolysis, rendering cooked rice sticky and cooked sweet potatoes sweet to the taste.

• Biological Roles of Complex Carbohydrates:

  • Starch: Primary energy storage polysaccharide in plants. Photosynthetic leaves convert light energy into sugars, which are transported to root tubers (e.g., potatoes, sweet potatoes, carrots, radishes, beets). During spring regrowth, plants mobilize stored starch from root tubers to sprout new leaves.
  • Glycogen: Primary energy storage polysaccharide in animals, stored concentratedly inside the liver and large skeletal muscle groups.
  • Cellulose: Major structural polysaccharide forming plant cell walls, raw timber, paper, linen, and cotton textiles. Insoluble in water.
  • Chitin: Structural polysaccharide forming the hard protective exoskeletons of arthropods, including cockroaches, shrimp, and crabs.

Questions & Discussion

• Question: After completing an exam monitored by Respondus Monitor, is it mandatory to wipe down the physical whiteboard?

  • Answer: Yes. Whiteboards must be wiped completely clean immediately after finishing the exam session to prevent taking photos or distributing confidential exam questions to peers.

• Question: When consuming animal tissue (such as beef steak), does foreign cow protein remain intact inside the body?

  • Answer: No. Foreign proteins enter the digestive tract where digestive enzymes break them down into constituent amino acids. The body then uses these individual amino acid building blocks to synthesize human-specific proteins required for biological function.