Chemistry of Life Flashcards

Vocabulary practice flashcards generated from the Week 1 Chemistry of Life lecture notes and learning objectives.

Atom

The basic structural unit of matter that makes up our bodies, consisting of subatomic particles including positively charged protons, uncharged neutrons, and negatively charged electrons.

Atomic Number

The total number of protons located in an atom's nucleus, which uniquely identifies a chemical element.

Neutral Atom

An atom that possesses an equal number of protons and electrons, resulting in a net electrical charge of zero.

Ion

An atom or group of molecules that possesses an uneven number of protons and electrons, giving it a net electrical charge.

Cation

A positively charged ion formed when an atom gives up negatively charged electrons.

Anion

A negatively charged ion formed when an atom accepts negatively charged electrons.

Ionization

The chemical process through which a neutral atom gains or loses electrons to become a charged ion.

Voltage

The electrical potential difference created by the physical separation of charged particles across a distance or membrane.

Current

The physical flow or movement of charged particles, such as ions passing through channels across cell membranes.

Molecule

A group of two or more individual atoms linked together and held in association by chemical bonds.

Ionic Bond

A chemical bond formed by the electrostatic attraction between two oppositely charged ions, such as in table salt ($\text{NaCl}$).

Covalent Bond

A strong chemical bond formed when participating atoms share valence electrons with one another.

Polar Covalent Bond

A covalent bond resulting from the unequal sharing of valence electrons between atoms, giving rise to slight partial positive ($\delta+$) and partial negative ($\delta-$) charges.

Nonpolar Covalent Bond

A covalent bond formed by the equal sharing of valence electrons between atoms, resulting in no charge imbalance across the bond (e.g., oxygen gas, $\text{O}_2$).

Hydrogen Bond

A weak attraction between neighboring molecules where a partially positive hydrogen atom is attracted to a partially negative region of another molecule, without sharing electrons.

Polarity

The unequal distribution of electrical charge across a molecule, such as in water where oxygen strongly attracts shared electrons away from hydrogen atoms.

Organic Molecule

A carbon-containing molecule essential to life, belonging to one of four main categories: carbohydrates, lipids, proteins, or nucleic acids.

Monomer

A single molecular unit that acts as a fundamental building block for constructing larger polymer chains.

Polymer

A macromolecule composed of many repeating molecular subunits or monomers joined together.

Carbohydrate

An organic macromolecule category made of single monosaccharides or polysaccharide polymers that serve as cellular fuel and short-term energy storage.

Glucose

A major six-carbon carbohydrate monomer (monosaccharide) utilized directly by cells as primary energy fuel.

Glycogen

A complex, highly branched carbohydrate polymer of glucose monomers used as the main carbohydrate energy storage molecule in animals.

Starch

A carbohydrate polymer composed of repeating glucose monomer units (typically containing $300\text{--}600$ units) synthesized by plants for energy storage.

Cellulose

A structural carbohydrate polymer of glucose monomers found exclusively in plant cell walls.

Triglyceride

A lipid composed of a glycerol backbone bound to 3 fatty acid tails, functioning in long-term energy storage and insulation.

Saturated Fatty Acid

A lipid chain containing only single covalent bonds between carbon atoms and maximum hydrogen saturation, commonly found in meat and dairy products.

Unsaturated Fatty Acid

A lipid chain containing one or more double covalent carbon bonds, creating bends in the tail and lower hydrogen saturation; found in plant oils, fish, and avocados.

Phospholipid

A membrane-forming lipid made of a glycerol backbone attached to 2 hydrophobic fatty acid tails and 1 hydrophilic phosphate-containing head group.

Hydrophilic

Having an affinity for water; refers to polar or charged molecular regions, such as the phosphate head of a phospholipid.

Hydrophobic

Lacking an affinity for water; refers to nonpolar molecular regions, such as the fatty acid tails of a phospholipid.

Steroid

A class of lipids characterized by a core structure of four fused carbon rings, synthesized from cholesterol.

Steroid Hormone

Lipid-derived chemical messengers synthesized from cholesterol (e.g., estrogen, testosterone) that transmit signals between cells.

Protein

A biological polymer composed of amino acid monomers whose physiological activity relies completely on its folded three-dimensional shape.

Primary Structure

The linear sequence or string of amino acids linked together by peptide bonds in a protein.

Protein Structural Hierarchy

The structural organizational levels of proteins: primary (amino acid sequence), secondary (local foldings like $\alpha$-helices and $\beta$-sheets), tertiary (overall 3D shape), and quaternary (complex of multiple polypeptide chains).

Enzyme

A specialized protein that acts as a biological catalyst to enable or accelerate chemical reactions in physiological processes.

Nucleic Acid

An organic polymer made of nucleotide monomers responsible for storing genetic information (DNA) and directing protein synthesis (RNA).

Nucleotide

The basic monomer unit of nucleic acids, consisting of a sugar, a phosphate group, and a nitrogenous base (adenine, thymine, guanine, or cytosine).

DNA (Deoxyribonucleic Acid)

A double-stranded nucleic acid polymer composed of adenine, thymine, guanine, and cytosine nucleotides that encodes genetic instructions within genes.

Gene Expression

The two-step process of converting DNA genetic instructions into functional proteins via transcription and translation.

Transcription

The first phase of gene expression where a gene's DNA sequence is copied into a complementary RNA nucleotide strand.

Translation

The second phase of gene expression where an RNA nucleotide sequence is decoded by ribosomes to assemble amino acids into a protein's primary structure.

ATP (Adenosine Triphosphate)

A nucleotide molecule that serves as the primary energy currency for cellular work, releasing usable free energy upon losing a phosphate group.

ATP Hydrolysis

The chemical reaction in which ATP is split by water to yield ADP and inorganic phosphate, releasing usable free energy to drive physiological reactions.