Unit 1 Biochemistry and Macromolecules - Comprehensive Study Notes

Exam overview and study resources

Exam: Wednesday; Unit 1 content; 50 multiple-choice questions
Covered material: introductory PowerPoints including regional terms, directional terms, homeostasis, negative and positive feedback, and all Chemistry 1 content; will touch a bit on Chemistry 2 as needed
After-class Q&A (bio 101): Wednesday 12:30 PM on Zoom; link on Moodle under Additional Resources → Unit 1
- Not mandatory; not an exam review; you can attend to ask unanswered questions from class
- Recording will be uploaded if you cannot attend
Two quizzes due on 9/9 at 11:59 PM
- Quiz 2: 10 MCQs (mostly content covered so far; mix of Chemistry 1 and some Chemistry 2)
- Quiz 3: 5 MCQs (focused on Chemistry 2 topics like buffers, etc.)
Additional study resources uploaded on Engage
- Chemistry review PowerPoint (click-through topics)
- Q&A link and a study guide expanding on learning objectives
- Learning objectives include: list body systems, survival needs, necessary life functions, structure-function, atomic condition, regional terms, planes, body cavities, and then chemistry topics (chemical makeup of the body, key elements, bonds)
Study tips shared by the instructor
- Use flashcards for directional/regional terms or print labeling sheets
- Do a “brain dump” exercise: write what you know about a topic to reinforce understanding
Acknowledge: the instructor encouraged active participation and asked for feedback on understanding

Inorganic compounds: acids, bases, and pH

Definitions
- Acids: proton donors; release hydrogen ions (H⁺) in solution; also called hydrogen ion donors
- Bases: proton acceptors; sponge up H⁺; raise pH
pH and hydrogen ion concentration
- pH is a measure of hydrogen ion concentration in a solution
- As [H⁺] increases, pH decreases; as [H⁺] decreases, pH increases
- Neutral pH = 7 (pure water)
- Blood pH is around 7.4 (slightly basic under normal conditions)
Common macroscopic terms
- Acids: acidic solutions have low pH and high H⁺ concentration
- Bases/alkaline solutions: high pH and lower H⁺ concentration
- Neutralization: acid + base → water + salt (e.g.,
  ext{NaOH} + ext{HCl}
  ightarrow ext{NaCl} + ext{H}_2 ext{O}
The four most common elements in body macromolecules: $ext{C}, ext{H}, ext{O}, ext{N}$ (with occasional S and P in some molecules)
Carbon dioxide, water, and carbonic acid in the blood
- CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻
- Carbonic acid (H₂CO₃) is a weak acid; bicarbonate (HCO₃⁻) is a weak base
- The carbonic acid–bicarbonate buffering system is the most important buffer in blood to maintain pH ~7.4
Buffering in blood
- When blood becomes acidic (high H⁺), the buffer system shifts to neutralize excess H⁺ by forming H₂CO₃ or consuming H⁺, helping keep pH within a narrow range (homeostasis)
- When blood becomes basic (low H⁺), the system shifts to release H⁺ by converting bicarbonate to carbonic acid and then CO₂ + H₂O (which is exhaled) to bring pH back down
Respiratory acid-base disturbances (conceptual scenarios)
- Respiratory distress/hypoventilation: CO₂ retention ↑ → carbonic acid ↑ → pH ↓ (respiratory acidosis)
- Hyperventilation: CO₂ loss ↓ → carbonic acid ↓ → pH ↑ (respiratory alkalosis)
- Rebreathing CO₂ (paper bag technique) can help prevent or correct alkalosis by increasing CO₂ levels in blood
Quick recap: key dynamics
- CO₂ and H₂O form carbonic acid; carbonic acid can dissociate to release H⁺ (acidifying) or bicarbonate can buffer by consuming H⁺ (basic direction)
- Buffer systems act to resist pH changes to maintain homeostasis
- The pH scale is logarithmic; small changes in H⁺ concentration reflect as changes in pH value

Introduction to organic macromolecules

What makes something organic?
- Organic molecules contain carbon
- Two notable exceptions: carbon dioxide (CO₂) and carbon monoxide (CO) are not considered organic
Carbon basics
- Carbon is tetravalent; forms four covalent bonds
- Carbon often forms chains and rings; many molecules are built from carbon skeletons

Energy-rich macromolecules: carbohydrates

General formula and structure
- Carbohydrates contain carbon, hydrogen, and oxygen; commonly written as
 $ext{(CH}2 ext{O)}n$
- Monomers: monosaccharides (glucose, fructose, ribose, etc.)
- Disaccharides: formed by dehydration synthesis of two monosaccharides (e.g., sucrose, maltose, lactose)
- Polysaccharides: long chains of monosaccharides (glycogen, starch, cellulose – structural vs storage roles)
Specific sugars
- Glucose (C₆H₁₂O₆) and fructose (C₆H₁₂O₆) are hexose monosaccharides (six carbons)
- Ribose and deoxyribose are five-carbon sugars (pentose): ribose in RNA; deoxyribose in DNA
Storage form in animals
- Glycogen stored primarily in the liver; breakdown via hydrolysis releases glucose into blood
- When glycogen stores are depleted, fat breakdown increases; prolonged starvation can lead to muscle or protein catabolism
Reactions in metabolism
- Dehydration synthesis (condensation): monomers join, water is released; forms covalent bonds
- Hydrolysis: addition of water breaks bonds, releasing monomers
Important notes
- Most carbohydrates are absorbed as monomers or small polymers after digestion
- Carbohydrates serve as a quick energy source and play structural roles in some organisms

Lipids and their diversity

General properties
- Lipids are hydrophobic (insoluble in water) due to their nonpolar nature
Triglycerides (fats where foods like butter are solid; oils are liquid)
- Structure: glycerol backbone + three fatty acid tails (triacylglycerol)
- Built by dehydration synthesis; broken down by hydrolysis for energy
- Functions: energy storage, insulation, and protection around organs
- Saturated vs unsaturated fats
- Saturated fats: no C=C double bonds; chains fully hydrogenated; typically solid at room temperature
- Unsaturated fats: contain one or more C=C double bonds; chains have kinks; typically liquid at room temperature
Phospholipids
- Structure: two fatty acid tails + a glycerol backbone + a phosphate-containing head group (often with a nitrogenous group)
- Amphipathic: hydrophilic (polar) head; hydrophobic (nonpolar) tails
- Form the phospholipid bilayer of cell membranes (two layers with hydrophobic tails inward and hydrophilic heads outward)
Steroids
- Built from cholesterol core with hydrophobic hydrocarbon rings (steroid nucleus)
- Cholesterol is essential for membrane fluidity and is a precursor for steroid hormones (testosterone, estrogen, progesterone) and vitamin D synthesis
- Cholesterol also contributes to plasma membrane structure
Prostaglandins and other signaling lipids
- Derived from fatty acids (e.g., arachidonic acid)
- Key roles: immune responses, uterine contractions during labor, clotting/hemostasis, and various signaling functions
Key takeaway about lipids
- Lipids have multiple roles: energy storage, membrane structure, signaling, and insulation/protection

Proteins: structure, function, and diversity

Building blocks
- Monomer: amino acids (there are 20 standard amino acids)
- Polymers formed by dehydration synthesis (peptide bonds) between amino acids
- Hydrolysis breaks peptide bonds to release amino acids
Major classes of proteins and roles
- Structural proteins: collagen (tensile strength), provide support and structure
- Enzymatic proteins: lactase (breaks down lactose), hexokinase (phosphorylates glucose as part of glycolysis)
- Transport proteins: hemoglobin (oxygen transport in blood)
- Regulatory proteins: insulin (regulates blood glucose)
- Antibodies: immune defense
Importance of protein diversity
- Proteins perform a wide range of functions from catalysis to transport, signaling, and defense
Broader context
- Proteins are the most functionally diverse macromolecules in the body

Nucleic acids: DNA and RNA

Core roles
- Store and transmit genetic information (DNA) and participate in protein synthesis (RNA)
Sugar components
- DNA uses deoxyribose; RNA uses ribose
Basic note
- Both are polymers built from nucleotide monomers; sequence determines genetic information and functional outcomes

Interconnections and overarching themes

Structure-function relationship
- Molecular structure (e.g., phospholipid bilayer, collagen fibers, protein active sites) dictates function and biological behavior
Homeostasis and metabolism
- Buffer systems and pH regulation maintain cellular and systemic stability; metabolism relies on hydrolysis and dehydration synthesis to remodel macromolecules
Energy flow and storage
- Carbohydrates provide quick energy; lipids provide long-term energy storage and insulation
Membranes and signaling
- Phospholipids form membranes; cholesterol modulates membrane properties; prostaglandins and other lipids participate in signaling and regulation
Genetic information and protein synthesis
- Nucleic acids store information; proteins execute most cellular functions; regulation of expression links genetics to phenotype

Practical takeaways for exam preparation

Be able to differentiate acids and bases and describe pH changes with hydrogen ion concentration
Understand the carbonic acid–bicarbonate buffering system and how respiration influences pH
Recall unit-one learning objectives: body systems, survival needs, life functions, structure-function, and core chemistry basics (atoms, bonds, regional terms, planes, and body cavities)
Distinguish monosaccharides, disaccharides, and polysaccharides; know examples (glucose, fructose, ribose, deoxyribose; sucrose, lactose, maltose; glycogen)
Describe triglycerides and the difference between saturated and unsaturated fats; explain phospholipids and the formation of the phospholipid bilayer
Recognize steroids (cholesterol as a backbone) and prostaglandins as signaling lipids
Recall protein categories and representative examples (collagen, lactase, hexokinase, hemoglobin, insulin, antibodies)
Remember nucleic acids as DNA/RNA with ribose/deoxyribose backbones

Quick reference formulas and concepts (LaTeX)

Acid-base equilibrium (carbonic acid buffer)
ext{CO}2 + ext{H}2 ext{O}
ightleftharpoons ext{H}2 ext{CO}3
ightleftharpoons ext{H}^+ + ext{HCO}_3^-
Buffer response and pH relation
- Acidic shift: increase in H⁺ lowers pH; bicarbonate buffer consumes H⁺ to form CO₂ and H₂O
- Basic shift: decrease in H⁺ raises pH; carbonic acid dissociates to release H⁺ or CO₂ is exhaled
Neutralization example
ext{NaOH} + ext{HCl}
ightarrow ext{NaCl} + ext{H}_2 ext{O}
Carbohydrate general structure
$ext{(CH}2 ext{O)}n ext{ (typical for monosaccharides)}$
Glucose formula (example of a hexose monosaccharide)
$ext{C}6 ext{H}{12} ext{O}_6$
Triglyceride formation (dehydration synthesis)
ext{Glycerol} + 3 ext{R-COOH}
ightarrow ext{Triglyceride} + 3 ext{H}_2 ext{O}
Phospholipid bilayer concept
- Hydrophilic head; hydrophobic tails; two-layer membrane (bilayer)

Notes on study logistics discussed in the transcript

The Q&A session is not mandatory and is not an official exam review; it is a resource to ask questions and get explanations
Recordings of the Q&A will be posted for students who cannot attend live
The study guide expands on the learning objectives from the lectures to help students prepare for the exam
Encouragement to use active study techniques (flashcards, labeling sheets, paragraph brain dumps) to reinforce understanding