Biol 20A: Cell & Molecular Biology - Chemical Principles

Vocabulary practice flashcards covering cell sizes, scales of resolution, cellular chemical composition, chemical bonds, water properties, pH, and physiological buffers from Biol 20A.

Minimum Resolvable by Unaided Eye

The smallest size resolvable by the unaided human eye, which is $0.2\,\text{mm}$ ($200\,\mu\text{m}$).

Minimum Resolvable by Light Microscope

The smallest size resolvable using a light microscope, which is $200\,\text{nm}$.

Minimum Resolvable by Electron Microscope

The smallest size resolvable using an electron microscope, which is $0.2\,\text{nm}$.

Cellular Water Content

Water accounts for $70\%$ of the total cell.

Protein Cellular Dry Weight

Proteins constitute $55\%$ of the cell's dry weight.

Major Elements in the Body

Oxygen ($65.0\%$), carbon ($18.5\%$), hydrogen ($9.5\%$), and nitrogen ($3.3\%$), which together make up about $96\%$ ($96.3\%$) of total human body mass.

Lesser Elements in the Body

Elements comprising about $3.6\%$ to $3.7\%$ of body mass: calcium ($1.5\%$), phosphorus ($1.0\%$), potassium ($0.4\%$), sulfur ($0.3\%$), sodium ($0.2\%$), chlorine ($0.2\%$), and magnesium ($0.1\%$).

Trace Elements

Elements making up less than $0.01\%$ of body mass individually (about $0.4\%$ total), including aluminum ($\text{Al}$), boron ($\text{B}$), chromium ($\text{Cr}$), cobalt ($\text{Co}$), copper ($\text{Cu}$), fluorine ($\text{F}$), iodine ($\text{I}$), iron ($\text{Fe}$), manganese ($\text{Mn}$), molybdenum ($\text{Mo}$), selenium ($\text{Se}$), silicon ($\text{Si}$), tin ($\text{Sn}$), vanadium ($\text{V}$), and zinc ($\text{Zn}$).

Atomic Number

The number of protons present in the nucleus of an atom.

Sugars

Monomeric building blocks of the cell that assemble into polysaccharides.

Fatty Acids

Monomeric building blocks of the cell that assemble into fats, lipids, and membranes.

Amino Acids

Monomeric building blocks of the cell that assemble into proteins.

Nucleotides

Monomeric building blocks of the cell that assemble into nucleic acids.

Biological Hierarchy

The organizational progression from elements ($\text{C, N, O, H, P, S}$) to molecules, macromolecules, macromolecular complexes/organelles, and ultimately cells.

Covalent Bond

A chemical bond in which one pair of electrons is shared between the outer shells of two atoms.

Ionic Bond

A chemical bond formed when an extremely electronegative atom steals electrons from its bonding partner.

Hydrogen Bond

A noncovalent attraction between a partial positive charge ($\delta+$) on a hydrogen atom and a partial negative charge ($\delta-$) on an electronegative atom (such as oxygen).

Properties of Water

Five key chemical properties: cohesion, high heat capacity, high heat of vaporization, lower density as a solid versus a liquid, and acting as a good solvent for polar molecules.

Dynamic Equilibrium of Water

A state in which water molecules dissociate into hydronium ($\text{H}_3\text{O}^+$) and hydroxide ($\text{OH}^-$) ions at the same rate at which they are reformed: $2\,\text{H}_2\text{O} \rightleftharpoons \text{H}_3\text{O}^+ + \text{OH}^-$.

Acidic Solution

A solution in which the concentration of hydrogen ions exceeds that of hydroxide ions ($[\text{H}^+] > [\text{OH}^-]$), having a pH less than 7.

Basic Solution

A solution in which the concentration of hydrogen ions is less than that of hydroxide ions ($[\text{H}^+] < [\text{OH}^-]$), having a pH greater than 7.

Buffer

A substance containing a weak acid and its corresponding base that minimizes changes in the concentrations of $\text{H}^+$ and $\text{OH}^-$ in a solution.

Carbonic Acid ($\text{H}_2\text{CO}_3$)

The weak acid and $\text{H}^+$ donor in the physiological buffer system that acts in response to a rise in pH.

Bicarbonate Ion ($\text{HCO}_3^-$)

The conjugate base and $\text{H}^+$ acceptor in the physiological buffer system that acts in response to a drop in pH.