Biochemistry: Carbohydrates, Lipids, and Proteins — Page-by-Page Notes (Condensed)

Page 1

• Biochemistry overview: study of chemical substances in living organisms and their interactions.

• Bioinorganic vs bioorganic: water and inorganic salts vs carbohydrates, lipids, proteins, nucleic acids.

• Major body mass composition (approximate): water >2/3; inorganic salts ~4–5%; bioorganic substances (proteins ~15%, lipids ~8%, carbohydrates ~2%, nucleic acids ~2%).

• Concept: same chemical principles apply to biomolecules as in organic chemistry; living systems extend functionality via polyfunctionality and interactions.

Page 2

• Quick quiz topics summarized: mass composition and abundance of bioinorganic vs bioorganic substances; major bioorganic class by mass in the human body.

• Visual mass composition figure (roughly): water dominates bioinorganic; proteins, lipids, sugars/nucleic acids are smaller portions of body mass.

Page 3

• Occurrence and functions of carbohydrates (plants and humans).

• Carbohydrates are the most abundant class of bioorganic molecules on Earth; in plants they dominate dry mass (about 75%).

• Photosynthesis: CO₂ + H₂O + solar energy → carbohydrates + O₂.

• Plant uses: cellulose (structural), starch (energy reserve).

• Human diet: major carbohydrate source from plants; ideal diet ~two-thirds carbohydrate by mass.

• Carbohydrates provide: energy (oxidation), short-term energy reserve (glycogen), carbon skeletons for other biomolecules, components of DNA/RNA, and membrane/cell-recognition roles when linked to lipids/proteins.

Page 4

• Carbohydrates: terminology and size classes.

• General formula for simple carbohydrates historically given as CH₂O; modern view: carbohydrate is a polyhydroxy aldehyde, polyhydroxy ketone, or a compound that yields such upon hydrolysis.

• Glucose = polyhydroxy aldehyde; fructose = polyhydroxy ketone.

• Key classifications by size: monosaccharide (one unit), disaccharide (two units covalently linked), oligosaccharide (3–10 units), polysaccharide (many units).

• Hydrolysis interconversions: all categories interrelate via hydrolysis.

Page 5

• Chirality: handedness; mirror-image forms exist (left- and right-handed).

• Chiral center: carbon atom with four different groups in tetrahedral geometry; molecule is chiral if it has a chiral center.

• Achiral vs chiral: achiral mirror images are superimposable; chiral mirror images are nonsuperimposable.

• Basic example: bromochloroiodomethane has four different substituents on a central carbon and is chiral.

• Glyceraldehyde is a simple example with at least one chiral center; glyceraldehyde shows mirror-image forms.

• Handedness in biomolecules: monosaccharides in nature are typically right-handed (D-forms) while amino acids in proteins are left-handed (L-forms).

Page 6

• Visuals and examples of chiral centers in simple molecules; ring members and chiral centers in cyclic structures.

• Guidelines for identifying chiral centers in acyclic and cyclic systems; presence of double bonds generally excludes chirality at that carbon.

• Ring systems: chirality can arise in some ring carbons if the two ring halves are different.

• Example problems (1-1): identify chiral centers in given molecules; ring chirality illustrated.

Page 7

• How to identify chiral centers in ring systems: rule that a carbon in a ring becomes chiral when the two halves (around the ring) are different and the attached substituents differ.

• Examples show that halogen substituents, as well as H/other groups, matter for chirality in rings.

• The concept of chiral centers is extended to molecules with multiple chiral centers, e.g., glyceraldehyde (two other centers possible in larger sugars).

Page 8

• Additional rules for judging chirality:

  • Carbons involved in multiple bonds cannot be chiral centers (fewer than four groups).

  • -CH and -CH₂ groups are not typically chiral when attached to identical substituents.

  • In ring systems, ring-halves distinction determines chirality.

• Example problems illustrate chiral vs achiral cyclics.

Page 9

• Why chirality matters: enantiomers often have different biological activities; right/left forms can lead to different interactions with receptors.

• All proteins, most fats, and all common carbohydrates are chiral; isomerism influences biology.

• Example: epinephrine enantiomers have different potencies.

• Monosaccharides are almost always chiral and mainly exist as D-forms in nature; amino acids in proteins are typically L-forms.

Page 10

• Summary of stereoisomerism concepts: enantiomers are nonsuperimposable mirror images; diastereomers are stereoisomers that are not mirror images.

• A simple thinking flowchart for classifying stereoisomers: check if molecules are constitutional isomers, whether they are mirror images, and whether they are superimposable.

• D/L nomenclature derived from Fischer projections and the highest-numbered chiral center.

Page 11

• Fischer projection basics for monosaccharides:

  • Chiral center represented at the intersection of vertical and horizontal lines; central atom (usually C) not shown explicitly.

  • Convention: vertical lines point to groups going into the page; horizontal lines point to groups coming out.

• D/L designation is assigned based on the orientation of the highest-numbered chiral center relative to the CHO group at the top.

Page 12

• Glyceraldehyde-derived enantiomer pairs; examples of monosaccharide Fischer projections for D- and L-glyceraldehyde.

• Open-chain vs cyclic monosaccharides and how the highest-numbered chiral center defines D or L for molecules with more than one chiral center.

• Examples of enantiomeric pairs for 2,3,4-trihydroxybutanal (a polyhydroxy ketone) and its Fischer projections.

Page 13

• Practice: drawing enantiomer Fischer projections; mirror image rule for monosaccharides.

• D/L designations for multi-center monosaccharides extend from glyceraldehyde; highest-numbered chiral center determines D/L for the pair; other centers accounted for by naming conventions (D-erythrose vs D-threose, etc.).

• Epimers: diastereomers differing at one chiral center.

Page 14

• Example problems: constructing Fischer projections for enantiomers of given monosaccharides; pairs that are diastereomers or enantiomers; counting possible stereoisomers (2^n for n chiral centers).

Page 15

• Quick quizzes recap: identifying enantiomers, diastereomers, and L/D configurations from Fischer projections.

• D/L designations defined at highest-numbered center; examples of erythrose and threose pairs.

Page 16

• Summary graphics: skeletal isomers and stereochemistry concepts; a quick guide to Fischer vs Haworth relation visuals.

Page 17

• Optical activity: enantiomers rotate plane-polarized light in opposite directions; dextrorotatory (+) vs levorotatory (-).

• Not all D- and L- enantiomers rotate light in the same direction; the direction is determined experimentally with a polarimeter.

• Interactions with chiral vs achiral solvents show differences in solubility and reaction rates.

Page 18

• Taste and receptor interactions can be enantiomer-dependent (e.g., carvone in spearmint vs caraway).

• Epinephrine example: D- vs L- forms show dramatically different receptor interactions.

• Anomeric effects and anomers (α and β) arise from cyclic hemiacetal formation; reactivity depends on the anomeric carbon geometry.

Page 19

• Summary of monosaccharide structures and properties: D-glucose, D-galactose, D-fructose, D-ribose, etc.; key differences in ring size, carbonyl type, and stereochemistry.

• D-Glucose is the most abundant and nutritionally important hexose; D-Fructose is a ketohexose; D-Galactose is an aldose epimer of glucose.

• Ribose is an aldopentose; differences between aldoses and ketoses arise in the open-chain form and subsequent cyclization.

Page 20

• Reactions of monosaccharides: oxidation to aldonic acids and uronic acids; reduction to alditols; glycoside formation; phosphate ester formation; amino sugar formation.

• Aldoses as reducing sugars; ketoses can become reducing sugars via isomerization to aldoses under basic/alkaline conditions.

• Glycosides are acetals formed from hemiacetals by reaction with alcohols; glucosides, galactosides, etc.

Page 21

• Aldoses and ketoses differ by carbonyl position; D-aldoses (e.g., glucose) are common; D-fructose is a ketose that cyclizes to five-membered or six-membered rings depending on carbon count.

• Important pairings: aldose vs ketose; D-forms are common in nature; L-forms are rare biologically.

Page 22

• Focus on triose, tetrose, pentose, and hexose Fischer projections and the number of chiral centers increases with carbon count in aldoses/ketoses.

• For glyceraldehyde (triose), one chiral center; for aldo-/keto-tetrose/pentose/hexose, chiral centers increase by one with each added carbon in the chain.

Page 23

• Biochemically Important Monosaccharides (summary): D-Glyceraldehyde, Dihydroxyacetone, D-Glucose, D-Galactose, D-Fructose, D-Ribose as key examples.

• D-Glucose: grape sugar; D-Fructose: levulose; D-Galactose: epimer of glucose at C-4; D-Ribose: ribose sugar in nucleic acids.

Page 24

• D-Glucose is abundant and nutritionally essential; blood glucose normal range; hormones insulin and glucagon regulate blood glucose; diabetes risk if dysregulated.

• D-Galactose is part of lactose in milk; epimer of glucose at C-4; major in glycoproteins and glycolipids.

• D-Fructose is found in fruits and honey; different metabolic fate than glucose; produced commercially as HFCS.

Page 25

• Cyclic forms of monosaccharides: hemiacetal formation between carbonyl group and an internal hydroxyl group.

• D-Glucose forms a six-membered ring (pyranose) via C5–C1 cyclization; two anomers: α and β; anomeric carbon is C-1.

• Equilibrium exists among α, β, and open-chain forms in solution; typical distribution for glucose in water: ~63% β-D-glucose, ~37% α-D-glucose, <0.01% open-chain.

• Anomeric carbon becomes chiral upon cyclization; interconversion between α and β forms occurs via open-chain form.

Page 26

• Terminology: anomeric carbon atom; α- vs β-anomer distinctions depend on OH position relative to CH₂OH; ring closure can interchange via open-chain intermediate.

• Haworth projections provide a two-dimensional view of cyclic forms; vertical orientation maps to substituent orientation on the chair/form.

Page 27

• Cyclic forms of other monosaccharides: fructose (furanose five-membered ring) and ribose (furanose-like five-membered ring in some forms).

• D-Fructose cyclization involves C-2 (keto) and C-5; D-Ribose cyclization involves C-1 and C-4.

• Pyranose = six-membered ring; furanose = five-membered ring.

• Specific names: D-Glucose in a-D-glucopyranose form; D-Fructose in a-D-fructofuranose form.

Page 28

• Distinguishing common monosaccharides by structural features: hexose vs pentose; aldose vs ketose; cyclic form ring size; alpha/beta forms.

• Example problem outcomes summarized for understanding D-forms and ring sizes.

Page 29

• Haworth projection details for sugars: ring size, anomeric carbon, D/L designation via CH₂OH orientation, alpha/beta depending on OH at C-1 relative to CH₂OH.

• Conversion rules: from Fischer to Haworth, substituents on right in Fischer go down in Haworth; left in Fischer go up in Haworth (for the typical D-series).

• Examples demonstrate conversion for D-mannose and others.

Page 30–31

• Haworth vs Fischer match-ups; common conventions for D- and L- forms in Haworth projections; notes on pi- and cis/trans-like relationships for ring substituents.

Page 32–35

• Reactions of monosaccharides (Section 1-12):

  • Oxidation to acidic sugars: aldose ends can become aldonic acids (e.g., glucose → gluconic acid) with Tollens/Benedict’s reagents.

  • Reduction to sugar alcohols (alditols, alditols): e.g., glucose → sorbitol.

  • Glycoside formation: hemiacetals react with alcohols to form acetals (glycosides).

  • Phosphate ester formation: phosphate esters (e.g., glucose-1-phosphate) form in metabolism.

  • Amino sugar formation: replacement of a hydroxyl with an amino group (e.g., glucosamine).

Page 36–39

• Disaccharides (Section 1-13):

  • Maltose: two glucose units; α(1→4) linkage; reducing sugar (one hemiacetal at C-1 on one unit).

  • Cellobiose: two glucose units; β(1→4) linkage; reducing sugar.

  • Lactose: galactose + glucose; β(1→4) linkage; reducing sugar (glucose unit hemiacetal).

  • Sucrose: glucose + fructose; α(1→2) linkage; nonreducing sugar (no freely opening hemiacetal).

• Hydrolysis products: disaccharides yield monosaccharides upon hydrolysis; glycosidic linkage determines products and reducing nature.

Page 40–41

• Blood sugar and lactase: lactose intolerance; lactase persistence varies by population; lactose hydrolysis yields glucose + galactose.

• Lactose in milk as major sugar; milk types (human vs cow) vary in lactose content; enzyme lactase is key for digestion.

• Lactose intolerance prevalence across populations; CFU notes and dietary implications.

Page 42–46

• Oligosaccharides: raffinose (galactose-glucose-fructose) and stachyose (raffinose with an extra galactose); linked via α(1→6) and β(1→2) glycosidic bonds.

• Undigested raffinose/stachyose reach colon; bacteria ferment them causing gas; Beano enzyme helps digestion.

• Blood type determinants involve specific oligosaccharide markers on red blood cells; shared tetrasaccharide core with variations (A/B) from additional sugars.

• Solanine (potato toxin) is an oligosaccharide-containing alkaloid; galactose/glucose units linked to a multi-ring alkaloid framework.

Page 47–50

• General characteristics of polysaccharides: polymers of monosaccharides; can be homopolysaccharides (one type) or heteropolysaccharides (two or more types).

• Branched vs unbranched structures; repeating units; sometimes disaccharide repeating units in heteropolysaccharides.

• Polysaccharides are not sweet and have low water solubility due to high molecular weight; often used as thickeners.

Page 51–53

• Storage polysaccharides: starch (plants) and glycogen (animals).

• Starch components: amylose (unbranched, α(1→4) linkages) and amylopectin (branched, α(1→4) and α(1→6)); branching increases number of chain ends and digestion rate.

• Glycogen: highly branched, α(1→4) and α(1→6) linkages; more compact and highly soluble; liver and muscle store glycogen; glycogenolysis/glycogenesis in metabolism.

• Iodine test for starch: blue-black color; digestion removes color as starch breaks down.

• Dietary implications: starch is major carbohydrate source; fiber in plant foods important for health.

Page 54–55

• Structural polysaccharides: cellulose and chitin.

• Cellulose: β(1→4) linkages; linear chains; forms rigid fibers due to extensive interchain hydrogen bonding; not digestible by humans; structural in plants; cotton and wood cellulose.

• Chitin: similar to cellulose but monomer is N-acetyl-D-glucosamine; major component in exoskeletons of arthropods; also in fungal cell walls.

• Comparison: both are structural polysaccharides; cellulose is glucose-based; chitin uses N-acetylglucosamine; all linkages are β(1→4).

Page 56–60

• Acidic polysaccharides: hyaluronic acid and heparin.

• Hyaluronic acid: repeating units of N-acetylglucosamine and D-glucuronate with alternating β(1→3) and β(1→4) linkages; very viscous; lubricates joints and eye vitreous humor.

• Heparin: highly sulfated, small polymer; acts as anticoagulant; used pharmaceutically to prevent clot formation; present in mast cells.

• Quick quiz recaps: structural features and functions of hyaluronic acid vs heparin.

• Dietary notes wrap up carbohydrate chapter: simple vs complex carbohydrates; natural vs refined sugars; dietary fiber health benefits.

• Glycolipids and glycoproteins (cell recognition): oligosaccharides attached to lipids/proteins on cell membranes function as recognition markers; ABO blood typing involves glycoproteins/oligosaccharides on red blood cells.

Page 61

• Concepts-to-remember digest: summarize core ideas from carbohydrates: biochemistry overview, carbon hydrates structure, chirality, Fischer/Haworth conventions, reactions, disaccharides, oligosaccharides, polysaccharides, dietary aspects, and cell-recognition roles.

Page 62–66

• Transition to Lipids: lipids are defined by solubility (insoluble in water, soluble in nonpolar solvents) rather than a single structural motif.

• Lipid classes (biochemical function): energy storage (triacylglycerols), membrane lipids (phospholipids, sphingolipids, cholesterol), emulsification (bile acids), messenger lipids (steroids, eicosanoids), protective coatings (waxes).

• Saponifiable vs nonsaponifiable: saponifiable lipids hydrolyze under basic conditions to yield smaller units; nonsaponifiable lipids do not.

Page 67–70

• Fatty acids: monocarboxylic acids with long unbranched chains; typically even-numbered due to biosynthesis; saturated vs unsaturated; cis configurations predominate; omega notation describes the position of the first double bond from the methyl end.

• Common fatty acids and shorthand: 16:0 palmitic acid; 18:1 oleic acid; 18:2 linoleic acid; 18:3 linolenic acid; 20:4 arachidonic acid.

• Omega-3 vs omega-6: omega-3 first double bond at C-3 from the methyl end; omega-6 first at C-6; essential fatty acids include linoleic (18:2, omega-6) and linolenic (18:3, omega-3).

Page 71–74

• Reactions of fatty acids and lipids (basics): hydrogenation (cis to trans conversion possible; unsaturated fats can be hardened); oxidation yields rancid products; saponification yields fatty acid salts.

• Fats vs oils: fats are solid/semi-solid at room temp, richer in saturated fats; oils are liquid at room temp, richer in unsaturated fats.

• Trans fats: produced by partial hydrogenation; associated with health risks similar to saturated fats; regulatory labeling concerns and efforts to reduce trans fats.

• Health notes: essential fatty acids must be obtained from diet; omega-3s associated with cardiovascular benefits; cold-water fish are rich sources of omega-3s.

Page 75–78

• Hydrogenation details and fat substitutes: Simplesse (protein-based fat substitute) and olestra (sucrose ester with multiple fatty acids) as examples of fat substitutes; benefits and drawbacks (calorie reduction vs GI effects and vitamin absorption).

• Lipid oxidation and antioxidants: vitamin C and E as natural antioxidants; BHA and BHT as synthetic antioxidants; oxidation leads to rancidity.

Page 79–83

• Emulsification lipids: bile acids emulsify dietary fats in the digestive tract; bile acids are derivatives of cholesterol with hydrophobic steroid nucleus and hydrophilic sides via amino acid conjugation (glycine or taurine).

• Complexed bile acids (glycocholic + taurocholic) increase emulsification; bile is produced by liver, stored in the gallbladder, released during digestion.

• Gallstones: cholesterol precipitation can form gallstones when bile acid balance is disrupted.

Page 84–86

• Messenger lipids: steroid hormones and eicosanoids; steroids are cholesterol derivatives; major classes: sex hormones (estrogens, androgens, progestins) and adrenocorticoids (mineralocorticoids like aldosterone and glucocorticoids like cortisol).

• Synthetic steroids: contraceptives and anabolic steroids; health risks and regulation (doping concerns).

• Eicosanoids: prostaglandins, thromboxanes, leukotrienes; derived from arachidonic acid; regulatory roles in inflammation, fever, pain, blood pressure, clotting, reproduction, sleep/wake cycle.

Page 87–90

• Cyclic and prostanoid chemistry: prostaglandins contain a cyclopentane ring; thromboxanes have a cyclic ether ring; leukotrienes contain conjugated double bonds; NSAIDs inhibit cyclooxygenase (COX) to reduce prostaglandin synthesis, reducing inflammation and fever.

• COX-1 vs COX-2: COX-1 maintains gastric mucosa; COX-2 more linked to inflammation; selective COX-2 inhibitors reduce inflammation with fewer GI side effects but have cardiovascular risks (e.g., Vioxx withdrawal).

Page 91–94

• Protective-coating lipids: waxes are long-chain fatty acids esterified to long-chain alcohols; properties are water-repellent and protective; examples include beeswax, carnauba wax, lanolin; waxes are often polymers.

• Distinction from mineral waxes (paraffin waxes): mineral waxes are nonbiological hydrocarbons.

Page 95–99

• Saponifiable vs nonsaponifiable lipids recapped with examples: saponifiable include triacylglycerols, glycerophospholipids, sphingophospholipids, sphingoglycolipids, and waxes; nonsaponifiable include cholesterol, bile acids, steroid hormones, eicosanoids.

• Number of linkages and building blocks determines saponifiability; nonsaponifiable lipids lack hydrolyzable links.

Page 100–106

• Membrane lipids: amphipathic molecules with a hydrophilic head and hydrophobic tails; the lipid bilayer forms a two-layer sheet with hydrophobic tails inside and polar heads outside.

• Phospholipids and sphingophospholipids as primary membrane lipids; cholesterol modulates membrane fluidity.

• Membrane proteins: integral and peripheral; transport across membranes via passive, facilitated, and active transport.

• Aquaporins allow water transport; membranes are dynamic and allow lateral mobility of lipids and proteins.

Page 107–113

• Phospholipids: glycerophospholipids and sphingophospholipids; glycerophospholipids have two fatty acids and a phosphate-containing head; sphingophospholipids have a fatty acid and a phosphate attached to the sphingosine backbone.

• Head vs tails: headgroup hydrophilic; tails hydrophobic; phosphatidylcholines, phosphatidylethanolamines, and phosphatidylserines discussed.

• Sphingomyelin is a sphingophospholipid with a choline head; important in myelin sheath.

• Sphingoglycolipids have fatty acid + carbohydrate head; cerebrosides and gangliosides are examples.

Page 114–118

• Cholesterol: steroid nucleus structure; four fused rings (3 six-membered rings + 1 five-membered ring); little polarity; sits in membranes altering fluidity; lipoprotein transport of cholesterol (LDL and HDL).

• Lipoproteins: HDL, LDL, VLDL, chylomicrons; density relates to protein vs lipid content; cholesterol transport in blood with LDL delivering cholesterol to tissues and HDL removing excess cholesterol to liver.

Page 119–123

• Cyclosporine and immunoglobulins: steroid and peptide interactions in immunology; immunoglobulins are glycoproteins with carbohydrate components; antibody structure: two heavy and two light chains with variable and constant regions; antigen binding at variable regions.

• Colostrum vs mature milk: immunoglobulins (IgA) and other nutrients; infant formula differences; lactation and transfer of immunity.

Page 124–131

• Glycoproteins and lipoproteins: collagen and immunoglobulins are glycoproteins; collagen contains nonstandard amino acids (hydroxyproline, hydroxylysine) and carbohydrate attachments; collagen glycosylation influences triple-helix assembly; vitamin C is essential for collagen biosynthesis.

• Immunoglobulins: heterotetramer structure with disulfide bonds; antigen binding occurs at variable regions; multiple antigen binding sites.

• Cyclosporine: immunosuppressive cyclic peptide used to prevent transplant rejection; unusual amino acid composition and modifications.

Page 132–136

• Four levels of protein structure recapped: primary, secondary, tertiary, quaternary.

• Primary structure: amino acid sequence and peptide bonds; determined by the N- to C-terminus order.

• Secondary structure: α-helix and β-pleated sheets stabilized by hydrogen bonds between the backbone C=O and N–H groups.

• Tertiary structure: three-dimensional arrangement of a single polypeptide; stabilized by disulfide bonds (cysteine), electrostatic interactions, hydrogen bonds, and hydrophobic interactions.

• Quaternary structure: arrangement of multiple polypeptide subunits in multimeric proteins; stabilized by similar noncovalent interactions as in the tertiary structure.

Page 137–140

• Alpha and beta structures, hydrogen bonding patterns, and unstructured segments in proteins.

• Disulfide bonds can be intrachain or interchain and are the strongest covalent interactions in protein structure.

Page 141–146

• Protein denaturation: loss of secondary, tertiary, and quaternary structure with retained primary sequence; denaturation can be caused by heat, pH changes, detergents, organic solvents, heavy metals, or reducing agents; renaturation possible in some cases.

• Denaturation affects function but not necessarily primary structure; coagulation and precipitation can occur when proteins unfold.

Page 147–151

• Protein classification by shape: fibrous vs globular; fibrous (e.g., keratin, collagen) are long and insoluble; globular (e.g., hemoglobin, myoglobin) are soluble and globular; function correlation with hydrophobic/hydrophilic surface exposure.

• Myoglobin vs hemoglobin: myoglobin stores oxygen in muscles (monomeric); hemoglobin carries oxygen in blood (tetrameric of 4 subunits).

• Structural examples: keratin fibers provide protection; collagen triple helix; silk fibroin β-sheets provide strength.

Page 152–156

• Conjugated proteins and glycoproteins: glycoproteins (carbohydrate attachments to proteins) include collagen and immunoglobulins; lipoproteins include lipids covalently linked to proteins; prosthetic groups define conjugation.

• Unstructured regions may provide functional flexibility and binding versatility.

Page 157–161

• Glycoproteins: collagen as glycoprotein due to nonstandard amino acids with carbohydrate attachments; collagen cross-linking and vitamin C role in proline/lysine hydroxylation.

• Immunoglobulins: antibody structure, variable regions, and antigen-binding sites; glycosylation affects stability/destinations.

• Lipoproteins: plasma lipoproteins carry lipids in blood; four major classes (chylomicrons, VLDL, LDL, HDL) distinguished by density and composition; LDL is “bad cholesterol,” HDL is “good cholesterol”; cholesterol transport and disease risk.

Page 162–166

• Quick review: primary, secondary, tertiary, quaternary structure; peptide bonds; protein denaturation; protein classification by function; examples of proteins (insulin, myoglobin, hemoglobin); immunoglobulins and lipoproteins.

Page 167–171

• Functional protein types recap: enzymes (catalysis), defense (immunoglobulins), transport (hemoglobin, transferrin), messenger (insulin, growth hormone), contractile (actin and myosin), structural (collagen, keratin), transmembrane (channels), storage (ferritin, myoglobin), regulatory and nutrient proteins; fuel reserves.

Page 172–176

• Glycoproteins and immunoglobulins continued: immunoglobulins overview; cyclosporine as an immunosuppressive drug from a fungus; glossary of immunoglobulin roles; colostrum content and infant immunity.

• Additional notes on blood group antigens and related glycoprotein structures.

Page 177–181

• Lipoprotein structure and function recap: plasma lipoproteins; density-based classification; chylomicrons, VLDL, LDL, HDL and their roles.

• Summary of the importance of HDL/LDL balance for heart disease risk; cholesterol distribution and transport in blood; cholesterol esters in lipoprotein cores.

• Conceptual links to nutrition and disease risk; cholesterol in membranes and as a hormone precursor.

Page 182–186

• Quick reference and problems: a broad set of exercise/problems connecting to the above topics; many questions require identifying components, linkages, and functional groups in proteins, glycoproteins, lipids, and carbohydrates; practice with primary structure, secondary structure, and protein function classification.

• Aimed at reinforcing understanding of the protein hierarchy, glycoproteins, lipoproteins, and biological roles of major biomolecules.

Summary by topic (condensed cross-chapter essentials)

• Carbohydrates

  • Definition and classification: monosaccharides, disaccharides, oligosaccharides, polysaccharides; empirical CH₂O notion expanded to polyhydroxy aldehydes/ketones.

  • Chirality and stereochemistry: enantiomers vs diastereomers; D/L designations in monosaccharides; Fischer and Haworth projections; cyclic forms (pyranose/furanose) and anomerism (α/β).

  • Key monosaccharides: D-glucose (most important in nutrition), D-galactose, D-fructose, D-ribose, glyceraldehyde, dihydroxyacetone.

  • Reactions: oxidation/reduction; glycoside formation; phosphorylation; amino sugars.

  • Disaccharides: maltose (glucose-glucose, α(1→4), reducing), cellobiose (glucose-glucose, β(1→4), reducing), lactose (galactose-glucose, β(1→4), reducing), sucrose (glucose-fructose, α(1→2), nonreducing).

  • Oligosaccharides and polysaccharides: raffinose, stachyose; starch, glycogen; cellulose, chitin; hyaluronic acid and heparin; dietary fiber.

  • Cell recognition: glycolipids and glycoproteins in membranes; blood types linked to oligosaccharide markers.

• Lipids

  • Solubility-based definition; major functional classes: energy storage (triacylglycerols), membranes (phospholipids, sphingolipids, cholesterol), emulsifiers (bile acids), messenger lipids (steroids and eicosanoids), protective lipids (waxes).

  • Fatty acids: saturated, monounsaturated (cis most common), polyunsaturated (cis); omega-3 and omega-6 families; essential fatty acids (linoleic and linolenic).

  • Triacylglycerols: glycerol + three fatty acids; fats vs oils; hydrolysis and saponification; hydrogenation and trans fats; fat substitutes.

  • Membrane lipids: glycerophospholipids and sphingophospholipids; amphipathic nature; cholesterol as a membrane regulator.

  • Sphingoglycolipids: cerebrosides and gangliosides; glycosyl headgroups; roles in membranes and brain.

  • Cholesterol: rigid steroid nucleus; membrane component; precursor to bile acids, hormones, vitamin D; lipoprotein transport (LDL/HDL) and heart-disease risk.

  • Eicosanoids: prostaglandins, thromboxanes, leukotrienes; derived from arachidonic acid; involved in inflammation, fever, pain, blood pressure, clotting, and reproduction; NSAIDs inhibit COX enzymes.

  • Waxes: biological waxes (esters of long-chain fatty acids and long-chain alcohols) with protective/coating roles.

  • Saponifiable vs nonsaponifiable: definitions and examples; importance in metabolism and digestion.

• Proteins

  • Core concepts: proteins are polymers of amino acids; amino acids are chiral except glycine; L-forms predominate in proteins.

  • Levels of structure: primary (sequence), secondary (α-helix and β-pleated sheets via backbone H-bonds), tertiary (3D folding via R-group interactions: disulfide bonds, electrostatics, H-bonds, hydrophobic effects), quaternary (assembly of multiple subunits in multimeric proteins).

  • Amino acids: 20 standard amino acids; categorized by side-chain polarity (nonpolar, polar neutral, polar acidic, polar basic); essential vs nonessential;

  • Proline is unique (cyclic side chain).

  • Peptides: peptide bonds (amide linkages) join amino acids; direction always N- to C-terminus; small peptides named via terminal amino acid and -yl on others; example Gly-Ala-Ser; cyclic peptides and disulfide bonds in some proteins.

  • Glycoproteins and lipoproteins: carbohydrates as prosthetic groups; collagen as a glycoprotein; immunoglobulins as glycoproteins; lipoproteins as protein carriers for lipids.

  • Enzymes: catalytic proteins; broad roles in metabolism.

  • Protein denaturation: disruption of secondary/tertiary/quaternary structure by heat, pH, detergents, solvents; primary structure remains intact; renaturation possible in some cases.

  • Protein nutrition: essential and nonessential amino acids; complete vs incomplete dietary proteins; complementary proteins.

  • Immunoglobulins: antibodies with Y-shaped structure; variable regions for antigen binding; disulfide bonds stabilize structure; glycosylation can affect function.

Notes on notation and formulas (LaTeX-ready examples):

• General carbohydrate formula: $ext{CH}<em>2 ext{O}$; oligo/polysaccharide general formula: igl( ext{CH}2 ext{O}igr)_n.

• Monosaccharide ring size and anomeric carbon are often denoted in Haworth projection terms, e.g., D-glucose as a-D-glucopyranose or a-D-glucopyranose depending on α/β.

• Fatty acid shorthand: e.g., linoleic acid: $ext{18:2 (Δ9,12)}$ or in omega notation: $ext{ω-6}$; palmitic acid: $ext{16:0}$; oleic acid: $ext{18:1 (Δ9)}$.

• Disaccharide linkages: maltose is $ext{Glc(α1→4)Glc}$; lactose is $ext{Gal(β1→4)Glc}$; sucrose is $ext{Glc(α1→2)Fru}$.

• Anomeric carbon designation: α vs β depends on orientation of the anomeric OH relative to CH₂OH in the ring.

If you’d like, I can tailor the notes to a specific subset (e.g., only Carbohydrates, or only Lipids) or reduce/expand any section for exam-focused review. I can also convert this into a PDF-ready outline or export a compact cheat-sheet for quick recall.

Biochemistry Overview

• Study of chemical substances in living organisms and their interactions.

• Major body mass: water (>2/3), inorganic salts ($\sim4-5\%$), bioorganic substances (proteins $\sim15\%$), lipids $\sim8\%$), carbohydrates $\sim2\%$), nucleic acids $\sim2\%$).

• Biomolecules follow organic chemistry principles but extend functionality via polyfunctionality and interactions.

Carbohydrates

• Definition & Classification: Polyhydroxy aldehydes/ketones or their derivatives. Classified as monosaccharides (1 unit), disaccharides (2), oligosaccharides (3-10), polysaccharides (many).

• Chirality & Stereochemistry: Chiral centers create mirror-image forms (enantiomers, diastereomers). D/L designation from Fischer projections (highest-numbered chiral center). Cyclic forms (pyranose/furanose) generate $ext{α/β}$ anomers at the anomeric carbon.

• Functions: Primary energy source, short-term energy storage (glycogen), structural components (cellulose), cell recognition (glycolipids, glycoproteins).

• Key Examples: D-Glucose (most abundant hexose), D-Fructose (ketohexose), D-Galactose (glucose epimer), D-Ribose (pentose).

• Reactions: Oxidation (aldonic/uronic acids), reduction (alditols), glycoside formation (acetals), phosphate ester formation, amino sugar formation.

• Disaccharides: Maltose ($ext{Glc(α1→4)Glc}$), Cellobiose ($ext{Glc(β1→4)Glc}$), Lactose ($ext{Gal(β1→4)Glc}$) are reducing sugars; Sucrose ($ext{Glc(α1→2)Fru}$) is nonreducing.

• Polysaccharides: Starch (amylose/amylopectin) and Glycogen (storage); Cellulose and Chitin (structural, $\beta(1\to4)$ linkages); Hyaluronic Acid and Heparin (acidic, functional).

Lipids

• Definition: Water-insoluble, nonpolar-solvent soluble organic compounds.

• Functional Classes: Energy storage (triacylglycerols), membranes (phospholipids, sphingolipids, cholesterol), emulsifiers (bile acids), messengers (steroids, eicosanoids), protective coatings (waxes).

• Fatty Acids: Long-chain carboxylic acids; saturated or unsaturated (predominantly cis); classified by omega notation (e.g., $ext{ω-3}$ vs $ext{ω-6}$); linoleic and linolenic are essential.

• Triacylglycerols: Esters of glycerol and three fatty acids. Fats (solid, saturated) vs. oils (liquid, unsaturated). Hydrogenation can produce trans fats. Saponification yields fatty acid salts.

• Membrane Lipids: Amphipathic molecules forming lipid bilayers. Glycerophospholipids and sphingophospholipids are primary. Cholesterol modulates fluidity.

• Cholesterol: Steroid nucleus (four fused rings); membrane component; precursor for bile acids, steroid hormones, vitamin D. Transported by lipoproteins (LDL, HDL).

• Eicosanoids: Derived from arachidonic acid; include prostaglandins, thromboxanes, leukotrienes. Regulate inflammation, pain, fever. NSAIDs inhibit COX enzymes.

• Waxes: Esters of long-chain fatty acids and long-chain alcohols, serving protective roles.

Proteins

• Structure Levels:

  • Primary: Amino acid sequence linked by peptide bonds (N- to C-terminus).

  • Secondary: Local folding (e.g., $\alpha$)-helix, $\beta$-pleated sheet) stabilized by backbone hydrogen bonds.

  • Tertiary: Overall 3D shape of a single polypeptide chain, stabilized by R-group interactions (disulfide bonds, electrostatics, H-bonds, hydrophobic effects).

  • Quaternary: Arrangement of multiple polypeptide subunits in multimeric proteins.

• Amino Acids: 20 standard types; chiral (L-forms predominate, except glycine); classified by side-chain polarity; essential vs. nonessential.

• Peptide Bonds: Amide linkages between amino acids.

• Denaturation: Loss of secondary, tertiary, and quaternary structure (primary intact) due to heat, pH, solvents; loss of function.

• Functions: Enzymes (catalysis), defense (immunoglobulins), transport (hemoglobin), structural (collagen, keratin), messengers (hormones), storage (myoglobin).

• Glycoproteins & Lipoproteins: Proteins with covalently attached carbohydrates or lipids, respectively; involved in cell recognition and transport.