Chapter 3: Biological Macromolecules Flashcards
What are the four classes of biological macromolecules?
Carbohydrates, Lipids, Proteins, Nucleic Acids
Define dehydration synthesis (condensation) and hydrolysis.
Dehydration synthesis: Joins monomers by removing water (e.g., forming a glycosidic bond in starch).
Hydrolysis: Breaks polymers by adding water (e.g., digesting starch into glucose).
What are monomers and polymers? Give examples.
Monomers: Small subunits (e.g., glucose for starch).
Polymers: Chains of monomers (e.g., cellulose).
List the three types of carbohydrates with examples.
Monosaccharides (glucose, fructose).
Disaccharides (sucrose, lactose).
Polysaccharides (starch, glycogen, cellulose).
Compare α-glucose and β-glucose. Why does this matter?
α-glucose: OH group below ring (forms starch).
β-glucose: OH group above ring (forms cellulose). Differences in bonding create distinct structures.
What is the function of starch vs. glycogen vs. cellulose?
Starch: Energy storage in plants.
Glycogen: Energy storage in animals (liver/muscles).
Cellulose: Structural support in plant cell walls.
Why can humans digest starch but not cellulose?
Enzymes (amylase) break α-1,4 glycosidic bonds in starch but not β-1,4 bonds in cellulose.
What are lipids? List their four main types.
Hydrophobic molecules:
Fats/Triglycerides, Phospholipids, Steroids, Waxes.
Describe the structure of a triglyceride.
Glycerol + 3 fatty acids. Saturated (no double bonds, solid) vs. unsaturated (double bonds, liquid).
What are trans fats? Why are they harmful?
Artificially hydrogenated oils with trans double bonds. Increase LDL cholesterol and heart disease risk.
Explain the structure of a phospholipid.
Glycerol + 2 fatty acids + phosphate group. Forms bilayers in cell membranes (hydrophilic heads, hydrophobic tails).
What are steroids? Example and function.
Four fused carbon rings. Example: Cholesterol (cell membrane fluidity, precursor to hormones like estrogen).
Define protein. What are their four levels of structure?
Polymers of amino acids.
Primary (sequence).
Secondary (α-helices/β-sheets via hydrogen bonds).
Tertiary (3D folding via R-group interactions).
Quaternary (multiple polypeptide subunits).
What is the peptide bond? Draw its formation.
Covalent bond between amino acids (carboxyl group + amino group → releases H₂O).
What causes protein denaturation? Give examples.
Loss of structure due to heat/pH changes. Example: Cooking egg white (albumin denatures).
What are enzymes? How do they work?
Catalytic proteins that lower activation energy. Bind substrates at active sites (e.g., amylase breaks starch).
Name 4 functions of proteins with examples.
Structural (collagen).
Transport (hemoglobin).
Defense (antibodies).
Catalysis (enzymes).
What are nucleic acids? Compare DNA and RNA.
DNA: Double-stranded, deoxyribose, stores genetic info.
RNA: Single-stranded, ribose, involved in protein synthesis.
Describe the structure of a nucleotide.
5-carbon sugar (ribose/deoxyribose) + phosphate group + nitrogenous base (A, T, C, G, U).
What is the central dogma of molecular biology?
DNA → RNA → Protein. DNA is transcribed to RNA, which is translated into proteins.
What are essential amino acids? How many exist for humans?
Amino acids humans cannot synthesize (9 out of 20). Example: Isoleucine, leucine.
What is a chaperonin? Function?
Protein that assists in proper folding of other proteins (prevents misfolding like in prion diseases).
Define hydrophobic vs. hydrophilic in protein folding.
Hydrophobic R-groups cluster inside; hydrophilic face outward (drives tertiary structure).
What is cellulose’s role in plant cells? Why is it indigestible?
Provides structural support. β-1,4 glycosidic bonds resist human enzymes.
What are omega-3 fatty acids? Health benefits?
Polyunsaturated fats with double bond at 3rd carbon. Reduce heart disease risk.
Explain the fluid mosaic model of cell membranes.
Phospholipid bilayer with embedded proteins (fluid structure).
What is glycogen? Where is it stored?
Branched glucose polymer (α-1,4 and α-1,6 bonds). Stored in liver and muscles.
How do waxes differ from fats? Function?
Long-chain fatty acids + alcohols. Waterproofing (e.g., plant cuticles, bee honeycombs).
What is the R-group in amino acids? Why is it critical?
Variable side chain determining amino acid properties (e.g., polar, charged, hydrophobic).
Describe the quaternary structure of hemoglobin.
Four polypeptide subunits (2 α, 2 β) with heme groups binding oxygen.
