Unit 1.2: Properties of Water, Biomolecules, Cell Transport, and Enzymes

Vocabulary flashcards generated from lecture notes on properties of water, biomolecules, cell membranes, and enzymes.

Polar Molecule

A molecule in which charges are unevenly distributed due to an unequal sharing of electrons caused by differences in electronegativity, such as in a water molecule.

Hydrogen Bond

A weak attraction formed between polar molecules, such as between the slightly positive hydrogen atom of one water molecule and the slightly negative oxygen atom of another.

Organic Molecules

Any molecules containing a carbon-hydrogen bond, such as $C_6H_{12}O_6$, $C_2H_4O_2$, and $C_8H_8O_3$.

Inorganic Molecules

Any molecules that do not contain a carbon-hydrogen bond, such as $CO_2$, $H_2O$, $CaCl_2$, $H_3PO_4$, and $Na_2SO_4$.

Cohesion

The attraction between molecules of the same substance, such as water molecules forming hydrogen bonds with one another.

Adhesion

The attraction between molecules of different substances, such as water molecules adhering to glass.

Surface Tension

A property related to cohesion that measures how difficult it is to stretch or break the surface of a liquid.

Biomolecules

Large organic molecules (also known as macromolecules) found in living things, categorized as carbohydrates, lipids, proteins, and nucleic acids.

Polymerization

The process of building larger compounds (polymers) by joining smaller repeating units (monomers) together.

Dehydration Synthesis Reaction

A chemical reaction in which monomers join together to form a polymer by losing a molecule of water ($H_2O$).

Monomer

A small chemical unit or building block that joins with other units to form a polymer.

Polymer

A large molecule composed of many smaller, repeating monomer units joined together.

Hydrolysis Reaction

A chemical process that breaks the bonds in polymers to create monomers by adding water molecules ($H_2O$).

Monosaccharides

Single-molecule simple sugars with the molecular formula $C_6H_{12}O_6$ that serve as the monomers of carbohydrates, including glucose, fructose, and galactose.

Polysaccharides

Complex carbohydrates formed from long chains of monosaccharides joined via dehydration synthesis, including starch, glycogen, and cellulose.

Saturated Fat

A lipid containing fatty acid chains with only single carbon-carbon bonds and the maximum number of hydrogen atoms, which is typically solid at room temperature.

Unsaturated Fat

A lipid containing fatty acid chains with at least one carbon-carbon double bond, which is liquid at room temperature.

Triglyceride

A lipid polymer constructed from three fatty acid chains attached to one glycerol molecule.

Amino Acid

The monomer of proteins, consisting of an amino group ($\text{-NH}_2$), a carboxyl group ($\text{-COOH}$), a central carbon atom, and a variable R-group.

Peptide Bond

A covalent bond formed between the amino group of one amino acid and the carboxyl group of another during a dehydration reaction.

Polypeptide

A long chain of amino acids joined together by peptide bonds, which folds into a functional protein.

Nucleotide

The monomer of nucleic acids composed of a 5-carbon sugar, a phosphate group ($\text{-PO}_4$), and a nitrogenous base.

Nucleic Acids

Polymers assembled from nucleotides, specifically DNA and RNA, that store and transmit genetic information.

Cell Membrane

A flexible, double-layered lipid bilayer surrounding all cells that regulates what enters and leaves the cell while protecting and supporting it.

Selectively Permeable

A property of biological membranes that allows some substances to pass across while blocking others.

Cell Wall

A strong supporting layer outside the cell membrane that shapes, supports, and protects cells in prokaryotes, plants, and fungi.

Enzymes

Proteins that act as biological catalysts to speed up chemical reactions by lowering the activation energy required.

Activation Energy

The minimum amount of energy needed to start a chemical reaction.

Active Site

The specific region on an enzyme where substrate molecules bind to undergo a chemical reaction.

Induced Fit

The model of enzyme activity in which the active site changes shape slightly to fit tightly around the substrate.

Denaturation

The loss of an enzyme's functional three-dimensional shape, rendering it inactive due to extreme changes in temperature or pH.