AP Biology Unit 1 – Chemistry of Life: Ultimate Study Notes (CED aligned)

What defines an atom’s atomic number?

The number of protons

How is an isotope different from the normal element?

It has a different number of neutrons

Why are electron configurations important?

They determine chemical reactivity

Give a biological use of radioisotopes.

Tracing metabolic pathways or PET scans

Which bond is the strongest in a biological molecule?

Covalent bond

What type of bond forms between water molecules?

Hydrogen bond

Why is water polar?

Unequal sharing of electrons in covalent bonds

Which bonds stabilize DNA base pairing?

Hydrogen bonds

Which property of water helps pull it up plant xylem?

Cohesion + adhesion (capillary action)

Why does ice float?

Hydrogen bonds create a lattice that lowers density

Why is water a good solvent for polar molecules?

Its partial charges interact with solutes

What is the role of water in buffering?

Resists changes in pH, maintains homeostasis

Monomer of carbohydrates?

Monosaccharides

Why can humans digest starch but not cellulose?

Humans can hydrolyze α-glucose linkages, not β-glucose linkages

Main functions of carbohydrates?

Energy storage and structural support

Function of phospholipids?

Form cell membranes (hydrophilic heads, hydrophobic tails)

Difference between saturated and unsaturated fats?

Saturated = no double bonds, solid; Unsaturated = double bonds, liquid

Function of steroids?

Hormonal signaling and membrane stability

Monomer of proteins?

Amino acids

Bonds stabilizing tertiary/quaternary structure?

Hydrogen, ionic, van der Waals, disulfide bridges

Why is protein shape important?

Shape determines function; denaturation disrupts activity

DNA strands are…?

Antiparallel, 5’ → 3’ orientation

Function of nucleic acids?

Store and transfer genetic information

Which group is acidic and releases H⁺?

Carboxyl (-COOH)

Which functional group is in ATP?

Phosphate (-PO₄)

Which group forms disulfide bridges in proteins?

Sulfhydryl (-SH)

Example molecule for hydroxyl group?

Ethanol

Dehydration synthesis does what?

Builds polymers by removing water

Hydrolysis does what?

Breaks polymers by adding water

Enzymes…

Lower activation energy without being consumed

Example of enzyme catalysis?

Catalase converts H₂O₂ → H₂O + O₂

Oxidation in metabolism means…

Loss of electrons

Reduction in metabolism means…

Gain of electrons

How does OIL RIG apply to cellular respiration?

Glucose is oxidized, oxygen is reduced

Competitive inhibition…

Inhibitor binds active site, competes with substrate

Noncompetitive inhibition…

Inhibitor binds elsewhere and changes enzyme shape

Vmax in enzyme kinetics…

Maximum reaction rate at saturating substrate