BILD 1: Midterm 1 Review (Lectures 2-8)

Vocabulary practice flashcards covering fundamental concepts from Lectures 2 to 8, including matter, chemical bonding, water, nucleic acids, proteins, carbohydrates, lipids, and cell biology.

Atom

A tiny particle of matter consisting of positively charged protons, uncharged neutrons, and negatively charged electrons.

Element

A pure chemical substance composed exclusively of one specific type of atom.

Proton

A positively charged subatomic particle located in the atomic nucleus whose number determines the identity of an element.

Valence Electrons

Electrons residing in the outermost shell (valence shell) of an atom that determine its chemical reactivity and bonding capacity.

Electronegativity

The ability of an atom to attract shared electrons toward itself, increasing from left to right and from bottom to top across the periodic table ($O > N > C \sim H$).

Covalent Bond

A chemical bond formed when two or more atoms share valence electrons to achieve stability; sharing one pair forms a single bond, while sharing two pairs forms a double bond.

Ionic Bond

A chemical bond formed by the complete transfer of electrons between atoms due to a large electronegativity difference, producing salts.

Emergent Properties

Novel characteristics that emerge in a compound that are distinct from the individual physical and chemical properties of its constituent elements.

Hydrogen Bond

A weak non-covalent attraction occurring when a hydrogen atom covalently bound to an electronegative atom is attracted to another electronegative atom (typically oxygen or nitrogen).

Van der Waals Interactions

Weak, transient attractions between molecules brought close together due to temporary, asymmetric distributions of electron density.

Solvent

The dissolving agent within a solution that dissolves a solute; in an aqueous solution, water functions as the solvent.

Solute

The substance that is dissolved by a solvent within a homogeneous solution.

Hydration Shell

A sphere of oriented water molecules that encloses each dissolved ion when an ionic compound dissociates in water.

Hydrophilic

Having an affinity for water; characteristic of polar covalent and ionic compounds that interact favorably with and dissolve in water.

Hydrophobic

Lacking an affinity for water; characteristic of nonpolar substances (such as hydrocarbons, oils, and fats) that do not dissolve in aqueous environments.

Hydrocarbon

An organic molecule consisting entirely of carbon and hydrogen atoms, capable of forming straight chains, branched frameworks, double bonds, and rings.

Nucleic Acids

Polymers (such as DNA and RNA) composed of nucleotide monomers that store, transmit, and express hereditary genetic information.

Deoxyribonucleic Acid (DNA)

A stable, double-stranded nucleic acid containing deoxyribose sugar and thymine that directs its own replication and controls cellular mRNA synthesis.

Ribonucleic Acid (RNA)

A single-stranded, comparatively less stable nucleic acid containing ribose sugar and uracil in place of thymine.

Monomer

A single repeating molecular subunit that serves as the building block for synthesizing larger polymers.

Polymer

A large macromolecule composed of numerous identical or similar monomer units joined together by covalent bonds.

Dehydration Reaction

A condensation reaction that covalently connects monomers to form polymers with the concurrent release of a water molecule ($H_2O$).

Hydrolysis

A chemical reaction that breaks the covalent bonds between monomers within a polymer through the addition and consumption of a water molecule ($H_2O$).

Amino Acid

The monomer building block of proteins, structured with a central alpha ($\alpha$) carbon bound to an amino group, a carboxyl group, a hydrogen atom, and a variable $R$ group.

Peptide Bond

The covalent bond formed between the carboxyl carbon of one amino acid and the amino nitrogen of another via a dehydration reaction.

Primary Structure

The linear sequence of amino acids covalently linked by peptide bonds within a polypeptide chain.

Secondary Structure

Localized conformational patterns (alpha helices and beta pleated sheets) formed by repetitive hydrogen bonding along the polypeptide backbone.

Tertiary Structure

The overall three-dimensional conformation of a single polypeptide chain determined by chemical interactions among the variable $R$ group side chains.

Quaternary Structure

The aggregated three-dimensional structure resulting from specific interactions between two or more distinct polypeptide subunits.

Monosaccharide

A simple sugar molecule having the general molecular formula $(CH_2O)_x$ (such as glucose or fructose), functioning as the monomer of carbohydrates.

Disaccharide

A carbohydrate composed of two monosaccharide units covalently linked by a glycosidic bond (such as sucrose or maltose).

Polysaccharide

A carbohydrate macromolecule consisting of long chains of linked monosaccharide subunits (such as starch, glycogen, cellulose, or chitin).

Glycosidic Linkage

The covalent bond that joins two carbohydrate monosaccharides through a dehydration synthesis reaction.

Fat

A lipid composed of one glycerol molecule linked to fatty acids, serving primarily in cellular energy storage in saturated or unsaturated forms.

Steroid

A class of lipids characterized by a carbon skeleton comprising four interconnected, fused carbon rings (such as cholesterol).

Phospholipid

An amphipathic lipid consisting of a hydrophilic glycerol and phosphate head attached to two hydrophobic fatty acid tails.

Eukaryotic Cell

A complex cell type containing a membrane-bound nucleus housing its genetic material, an endomembrane system, and specialized membrane-bound organelles.

Prokaryotic Cell

A unicellular organism (Bacteria and Archaea) lacking a membrane-delimited nucleus and membrane-bound organelles, with DNA localized in the cytoplasm.

Endomembrane System

The interconnected network of internal eukaryotic membranes that synthesize, modify, package, and transport lipids and proteins (includes the nuclear envelope, ER, Golgi, lysosomes, vesicles, and plasma membrane).

Mitochondria

Cellular organelles that utilize oxygen to synthesize chemical energy in the form of $ATP$ from sugars via cellular respiration.

Ribosome

A molecular machine made of ribosomal RNA and proteins that performs protein synthesis in both prokaryotic and eukaryotic cells.

Lysosome

A membrane-enclosed digestive organelle in animal cells containing enzymes to degrade macromolecules and cellular debris.

Chloroplast

A photosynthetic organelle present in plant cells that captures solar energy from sunlight to synthesize sugars.

Central Vacuole

A prominent organelle in plant cells that absorbs water, stores nutrients, and generates turgor pressure for structural rigidity.

Cell Wall

A rigid extracellular barrier composed of polysaccharides located external to the plasma membrane in plants and prokaryotes.