Molecules Of Life Flashcards
Distinguish between condensation reactions and hydrolysis. Provide examples for each class of biomolecules.
Condensation Reaction (Dehydration Synthesis): Two molecules bond by removing a water molecule.
• Example: Glucose + Fructose → Sucrose + H₂O
Hydrolysis Reaction: A molecule is broken down by adding water.
• Example: Sucrose + H₂O → Glucose + Fructose
Biomolecule Examples:
• Carbohydrates: Starch synthesis (condensation), starch breakdown (hydrolysis).
• Proteins: Peptide bond formation (condensation), protein digestion (hydrolysis).
• Lipids: Triglyceride formation (condensation), fat digestion (hydrolysis).
• Nucleic Acids: DNA synthesis (condensation), DNA breakdown (hydrolysis).
Provide examples of human proteins and their functions.
Hemoglobin: Transports oxygen in blood.
Collagen: Provides structural support in skin and connective tissues.
Insulin: Regulates blood sugar levels.
Actin & Myosin: Involved in muscle contraction.
Antibodies: Help fight infections.
Enzymes (e.g., Amylase, Pepsin): Speed up biochemical reactions.
Compare and contrast sucrose and lactose in terms of structure and biological role.
Sucrose: Made of glucose + fructose, found in plants (e.g., sugarcane).
Lactose: Made of glucose + galactose, found in milk (mammals).
Both: Disaccharides that provide energy, but lactose is broken down by lactase, whereas sucrose is broken down by sucrase.
Explain the difference between lactose intolerance and lactase persistence.
Lactose Intolerance: Body does not produce lactase, leading to digestive issues when consuming dairy.
Lactase Persistence: Body continues to produce lactase into adulthood, allowing digestion of lactose.
Describe and sketch amylase, amylopectin, and glycogen. Explain how structure relates to function.
Amylose: Unbranched, linear starch—efficient for energy storage.
Amylopectin: Branched starch—allows for faster energy release.
Glycogen: Highly branched—stored in liver/muscles for quick energy access.
How do beta-1,4 linkages in cellulose result in a different structure and function than polysaccharides with alpha linkages?
Beta-1,4 linkages in cellulose form straight, rigid fibers, making it structurally strong (cell walls in plants).
Alpha linkages in starch/glycogen form coiled, branched structures, making them easier to digest for energy.
Q: Distinguish between fats and oils in terms of structure and function.
Fats (e.g., butter, lard): Saturated fatty acids, solid at room temp, used for long-term energy storage & insulation.
Oils (e.g., olive oil, fish oil): Unsaturated fatty acids, liquid at room temp, used for quick energy & cell membrane flexibility.
Sketch the general structure of an amino acid
Describe the pathway of excess amino acids in body cells.
Excess amino acids cannot be stored, so they undergo deamination in the liver, removing the amino group (NH₂).
The amino group is converted to urea and excreted via urine.
The remaining carbon skeleton is used for energy (gluconeogenesis) or stored as fat.
List the 3 categories of R-groups and explain essential amino acids.
- Nonpolar (hydrophobic) – e.g., leucine
- Polar (hydrophilic) – e.g., serine
- Charged (acidic/basic) – e.g., glutamate (+) or lysine (-)
Essential amino acids: Cannot be synthesized by the body and must be obtained from food (e.g., lysine, tryptophan).
Describe peptide bond formation and the primary structure of a protein.
Peptide bond: Formed by a condensation reaction between the carboxyl group (COOH) of one amino acid and the amino group (NH₂) of another, releasing H₂O.
Primary structure: A linear sequence of amino acids linked by peptide bonds.
Distinguish between alpha-helices and beta-pleated sheets in secondary protein structure.
Alpha-helices (α-helices): Coiled, spiral structures stabilized by hydrogen bonds. Found in keratin.
Beta-pleated sheets (β-sheets): Folded, sheet-like structures stabilized by hydrogen bonds. Found in silk.
Describe the relationship between the primary and tertiary structure of a protein.
The primary structure (amino acid sequence) determines the tertiary structure (3D shape) by influencing how the protein folds.
Mutations in the primary sequence can alter the folding, affecting function (e.g., sickle cell hemoglobin).
List 4 types of interactions that contribute to a protein’s tertiary structure.
- Hydrogen bonds – Between polar R-groups.
- Ionic bonds – Between charged R-groups.
- Disulfide bridges – Covalent bonds between sulfur atoms (cysteine).
- Hydrophobic interactions – Nonpolar R-groups cluster away from water.
Why is the tertiary structure of a protein dynamic and not static?
Proteins constantly shift their shape for function, such as enzyme activity, ligand binding, and cellular signaling.
Environmental factors (e.g., pH, temperature) can temporarily alter their shape.
