AP Biology Macromolecules and Water Properties

Vocabulary practice flashcards covering nucleic acids, lipids, DNA/RNA structures, and water properties from the lecture notes.

Nucleotide

The monomer of nucleic acids, consisting of a phosphate group, a pentose sugar, and a nitrogenous base.

Phosphodiester linkage

The covalent bond that joins the phosphate group of one nucleotide to the hydroxyl group on the pentose sugar of another nucleotide.

Antiparallel

The orientation of double-stranded DNA where one strand runs in the $5'$ to $3'$ direction while the complementary strand runs in the $3'$ to $5'$ direction.

Purines

Nitrogenous bases made up of a double-ring nitrogen structure, consisting of adenine and guanine.

Pyrimidines

Nitrogenous bases made up of a single nitrogen ring, consisting of cytosine, thymine, and uracil.

Deoxyribose

The five-carbon pentose sugar found in DNA, characterized by having a single hydrogen atom attached to its second carbon.

Ribose

The five-carbon pentose sugar found in RNA, characterized by having a hydroxyl group attached to its second carbon.

Ester linkage

The covalent bond formed between a hydroxyl group of glycerol and the carboxyl group of a fatty acid through a dehydration reaction.

Saturated fatty acid

A fatty acid chain with only single bonds between carbon atoms, saturated with hydrogen atoms, causing it to be solid at room temperature.

Unsaturated fatty acid

A fatty acid chain containing one or more double bonds between carbon atoms, resulting in kinks that make it liquid at room temperature.

Amphipathic

A property of a molecule, such as a phospholipid, that possesses both a polar (hydrophilic) region and a nonpolar (hydrophobic) region.

Steroids

Nonpolar lipids composed of four fused carbon rings that act as signaling molecules and pass directly through hydrophobic biological membranes.

Polar covalent bond

A covalent bond between atoms where electrons are shared unequally due to differences in electronegativity, creating partial positive and partial negative charges.

Hydrogen bond

An attractive electrostatic interaction between a partially positive hydrogen atom of one polar molecule and a partially negative atom (such as oxygen) of another polar molecule.

Cohesion

The attractive force between molecules of the same substance, such as water molecules forming hydrogen bonds with each other.

Adhesion

The attractive force between water molecules and different polar substances, such as water clinging to the walls of plant xylem.

Capillary action

The process by which water moves upward through narrow spaces against gravity due to the combined effects of cohesion and adhesion.

Specific heat

The amount of heat energy required to raise the temperature of a substance, which for water is high ($4.184\,\text{J/g}$) due to its hydrogen bonding network.

Evaporative cooling

The property wherein liquid water absorbs heat energy to break hydrogen bonds and transition into a gas, removing heat and cooling the remaining liquid surface.

pH

A logarithmic measure of hydrogen ion concentration in a solution, mathematically defined as $pH = -\log[H^+]$.