Biochemistry Basics: Reaction Rates, Water, pH, and Organic vs Inorganic Molecules

Flashcards covering key concepts from reaction rates to lipids and membranes, drawn from the biochemistry lecture notes.

How does heat affect the rate of chemical reactions?

Increases molecular motion and collisions, leading to a faster reaction.

How does increasing reactant concentration influence reaction rate?

More collisions between reacting molecules, increasing the rate.

How does particle size affect reaction rate?

Smaller particles move more easily, collisions occur more readily, speeding the reaction.

What is a catalyst?

A substance that speeds a reaction without being consumed or permanently changed, by providing an alternative pathway.

What are enzymes?

Biological catalysts that speed biochemical reactions in cells.

What defines organic compounds?

Organic compounds contain carbon (with rare exceptions).

What are two exceptions to the rule 'carbon-containing = organic'?

Carbon monoxide (CO) and carbon dioxide (CO2).

What are inorganic compounds?

Compounds that do not contain carbon (e.g., water, salts).

Why is carbon central to life?

Carbon forms four covalent bonds, enabling three-dimensional, diverse biomolecules.

What makes water a polar solvent and why is hydrogen bonding important?

Water is polar and forms hydrogen bonds, giving high heat capacity, high heat of vaporization, solvent properties, and cushioning.

What happens when salts are dissolved in water (dissociation)?

Water surrounds ions and splits the salt into cations and anions (hydration/dissociation).

Name some common electrolytes in blood.

Sodium (Na+), potassium (K+), chloride (Cl-), calcium (Ca2+), phosphate (PO4^3-).

How are acids and bases defined in aqueous solutions?

Acids donate hydrogen ions; bases accept hydrogen ions or produce hydroxide; related to pH.

What is the pH scale and what do its numbers mean?

0-14 scale; 7 is neutral; below 7 acidic; above 7 basic; lower numbers = higher [H+].

What is the relationship between pH and hydrogen ion concentration?

pH is the negative log of [H+]; a one-unit change represents a tenfold change in [H+].

What is the physiological pH of blood?

Approximately 7.4 (slightly basic).

What is a buffer pair? Give an example.

A conjugate acid-base pair that resists pH changes; example: carbonic acid (H2CO3) and bicarbonate (HCO3-).

What is dehydration synthesis?

A reaction that joins monomers by removing water to form a polymer.

What is hydrolysis?

A reaction that breaks polymers into monomers by adding water.

What are the main hexose monosaccharides?

Glucose, fructose, and galactose (C6H12O6).

What is a pentose sugar and its role?

Five-carbon sugar used to build DNA/RNA; e.g., deoxyribose (DNA).

What are disaccharides and examples?

Two monosaccharides linked; sucrose (glucose+fructose), maltose (glucose+glucose), lactose (glucose+galactose).

What is glycogen and where is it stored?

A branched glucose polymer stored in liver and skeletal muscle.

What are the main classes of lipids?

Triglycerides, phospholipids, and steroids.

Describe triglyceride structure.

Glycerol backbone with three fatty acid chains; energy storage; nonpolar; hydrophobic.

What makes fats saturated vs unsaturated?

Saturated fats have no double bonds; straight chains; solid at room temperature. Unsaturated fats have one or more double bonds, causing kinks; liquid at room temperature; generally healthier.

What are trans fats and why are they harmful?

Trans fats result from hydrogenation; unsaturated fats converted to unnatural trans configuration; associated with increased LDL and decreased HDL; health risks.

What is a phospholipid and why are they amphipathic?

A modified triglyceride with two fatty acid tails and a phosphate head; amphipathic: hydrophobic tails, hydrophilic head; forms cell membranes.

How do phospholipids organize in water?

Tails face inward away from water; heads face outward; form lipid bilayers.

What is cholesterol's role in membranes and as a precursor to other molecules?

Stabilizes membranes by occupying spaces between phospholipids; precursor to steroid hormones and vitamin D.