Unit 1: The Chemistry of Life Flashcards

A set of vocabulary flashcards covering the chemistry of life, including water properties, atomic structure, macromolecules, and chemical reactions.

Protons

Positively-charged subatomic particles found in the center of an atom, called the nucleus.

Electrons

Negatively-charged subatomic particles located outside the nucleus in regions called shells.

Valence electrons

Electrons located in the outermost shell that directly determine how an atom shares or transfers electrons to bond with other atoms.

Nucleus (Atomic)

The center of an atom containing protons and neutrons; it is roughly $1$ million times smaller than the nucleus of a cell.

Atomic Mass

The sum of the protons and neutrons in an atom ($\text{protons} + \text{neutrons}$).

Polar Covalent Bond

A bond involving the unequal sharing of electrons, occurring when an atom with more protons (such as Oxygen) pulls shared electrons closer to itself.

Electronegativity

An atom's attraction for, or pull on, shared electrons.

Hydrogen Bonds

Relatively weak intermolecular attractions between a slightly positive ($\text{δ}+$) hydrogen atom and a slightly negative ($\text{δ}-$) oxygen or nitrogen atom.

Specific Heat Capacity

The amount of heat energy that must be gained or lost to change the temperature of $1\,g$ of a substance by $1^{\circ}\text{C}$.

Thermal Buffering

A process where water resists temperature changes by releasing heat energy when H-bonds form (cooling) or absorbing heat to break H-bonds (warming).

Heat of Vaporization

The amount of additional heat energy that must be gained to change $1\,g$ of liquid water to $1\,g$ of gaseous water at the same temperature.

Evaporative Cooling

A process where high-energy molecules evaporate and remove thermal energy, lowering the average kinetic energy and temperature of the remaining liquid.

Cohesion

A property where polar water molecules form hydrogen bonds and stick to each other.

Adhesion

A property where polar water molecules form hydrogen bonds and stick to other types of polar molecules.

Surface Tension

A phenomenon caused by stronger cohesion between water molecules at the surface, allowing certain organisms to walk on water.

Capillary Action

The upward movement of water against gravity in tiny spaces, driven by a combination of cohesion and adhesion.

Density Anomaly of Water

A unique property where ice is less dense than liquid water because hydrogen bonds lengthen to their maximum distance during freezing; water is most dense at $4^{\circ}\text{C}$.

Brumation

A reptile form of hibernation, such as in alligators, where the heart rate drops to as low as $3$ beats per minute to conserve energy.

Monomers

The individual, single sub-units that serve as the chemical building blocks for larger, complex structures.

Polymers

Complex molecular chains formed by covalently bonding multiple smaller monomers together in sequence.

Dehydration Synthesis

A chemical reaction that joins monomers into a polymer by removing a hydrogen atom ($\text{-H}$) from one and a hydroxyl group ($\text{-OH}$) from another, releasing a water ($H_2O$) molecule.

Hydrolysis

A chemical reaction that breaks down a polymer into monomers by splitting a water ($H_2O$) molecule and adding a hydrogen atom to one monomer and a hydroxyl group to the other.

Functional Groups

Specific clusters of atoms attached to a molecule's carbon skeleton that act as chemical 'handles' and determine how a molecule behaves.

Hydroxyl Group

A highly polar, hydrophilic functional group ($\text{-OH}$) used in all four macromolecules for dehydration synthesis and hydrolysis.

Carboxyl Group

A polar, acidic functional group ($\text{-COOH}$) that releases a hydrogen ion into solution; found in amino acids and fatty acids.

Amino Group

A polar, basic functional group ($\text{-NH}_2$) that picks up free-floating $H^+$ ions; found in the backbone of amino acids.

Sulfhydryl Group

A weakly polar functional group ($\text{-SH}$) that forms covalent disulfide bridges to stabilize the 3D structure of proteins.

Methyl Group

A nonpolar, hydrophobic functional group ($\text{-CH}_3$) that does not participate in linking or breaking monomers.

Monosaccharides

Simple sugar monomers containing Carbon, Hydrogen, and Oxygen in a $1:2:1$ ratio; the building blocks of carbohydrates.

Glycosidic Linkages

The covalent bonds that connect monosaccharides to form polysaccharides.

Starch

A polysaccharide used by plants for long-term energy storage, containing alpha ($\alpha$) 1-4 and 1-6 linkages.

Cellulose

A structural polysaccharide in plant cell walls made of straight, unbranched chains with beta ($\beta$) 1-4 linkages.

Saturated Fatty Acids

Fats with no double bonds between carbon atoms, resulting in straight chains that are solid at room temperature.

Unsaturated Fatty Acids

Fats with one or more double covalent bonds between carbon atoms, resulting in bent chains that are liquid at room temperature.

Phospholipids

Lipids with a hydrophilic phosphate head and two hydrophobic fatty acid tails; they form the structural foundation of cell membranes.

Enzymes

Protein molecules that catalyze chemical reactions by binding to substrates at an active site and reducing activation energy.

Peptide Bonds

Covalent bonds formed between the carboxyl group of one amino acid and the amino group of the adjacent amino acid.

Disulfide Bridges

Strong covalent links ($S-S$ bonds) formed between two cysteine amino acids that lock a protein's tertiary structure into place.

Primary Structure

The level of protein structure consisting of the unique sequence of amino acids in a polypeptide chain.

Secondary Structure

Protein structure involving the formation of alpha-helices ($α$-helices) and beta-pleated sheets ($β$-pleated sheets) stabilized by hydrogen bonding.

Tertiary Structure

The overall three-dimensional shape of a polypeptide resulting from R-group interactions such as hydrogen bonds, ionic bonds, and disulfide bridges.

Nucleotides

The monomers of nucleic acids consisting of a $5$-carbon sugar, a phosphate group, and a nitrogenous base.

Phosphodiester Bonds

Covalent bonds that connect the sugar-phosphate backbone of DNA and RNA molecules.

Antiparallel

The structural orientation of the DNA double helix where the two strands run in opposite $5'$ to $3'$ directions.

RNA World Hypothesis

The proposal that RNA was the first molecule to store genetic information and catalyze chemical reactions prior to the evolution of DNA and proteins.