Biochemistry: Macromolecules and Cellular Chemistry

Vocabulary flashcards covering the four major classes of macromolecules—carbohydrates, lipids, proteins, and nucleic acids—along with their monomers, structural levels, chemical bonds, and biological functions.

Macromolecule

A large molecule that carries out major function(s) within a cell.

Monomer

A small molecule that acts as a fundamental building block for assembling larger molecules.

Polymer

A larger molecule formed by multiple monomers bonded together.

Carbohydrates

A class of macromolecules (sugars) utilized for energy storage (such as glycogen and starch) and structural support (such as cellulose).

Monosaccharide

A single carbohydrate monomer unit, of which glucose is the most prominent example.

Disaccharide

A carbohydrate molecule composed of two bonded monosaccharide monomers.

Polysaccharide

A carbohydrate polymer formed by multiple monosaccharide monomers linked together.

Glucose

The most famous monosaccharide monomer, possessing the chemical formula $C_6H_{12}O_6$.

Lipids

A class of non-polar macromolecules (fats) used for long-term energy storage and cell structures, which includes fatty acids, glycerides, phospholipids, and steroids.

Fatty Acids

Lipid structures consisting of long chains of carbon with hydrogen atoms bonded along the sides.

Saturated Fatty Acid

A fatty acid chain containing only single bonds between carbon atoms, holding the maximum possible number of hydrogens and the maximum potential energy.

Unsaturated Fatty Acid

A fatty acid chain containing one or more double bonds between carbon atoms, which reduces the maximum energy of the chain because two carbons share an additional bond.

Phospholipid

The primary lipid of plasma membranes, composed of a polar hydrophilic phosphate head and two nonpolar hydrophobic fatty acid tails linked by a glycerol.

Phospholipid Bilayer

A membrane arrangement consisting of two opposing sheets of phospholipids, where polar hydrophilic heads face the surrounding water and nonpolar hydrophobic tails orient inward away from water.

Cholesterol

A steroid lipid found in the plasma membrane that makes it more tolerant to increases in temperature; it also serves as an energy storage molecule and the building block of all steroids.

Lipoproteins

Carrier complexes in the bloodstream that transport cholesterol, categorized into Low Density Lipoproteins (LDL) and High Density Lipoproteins (HDL).

Proteins

The specialized 'doers of the cell' that perform tasks ranging from digesting food, carrying oxygen, and transporting cellular nutrients, to determining hair and skin color.

Amino Acids

The $20$ different monomer building blocks of proteins, each structured with an amino group, a carboxyl group, a hydrogen atom, and a distinctive variable side chain ($R$ group).

Polypeptide Chain

A polymer formed by amino acids joined together by peptide bonds, which folds into a functional protein depending on the sequence and chemical nature of the side chains.

Primary Protein Structure

The first level of protein structure, characterized by the specific linear sequence of amino acids in a polypeptide chain.

Secondary Protein Structure

The second level of protein structure, formed when hydrogen bonds between backbone atoms create regular repeating patterns: alpha helices and beta sheets.

Tertiary Protein Structure

The third level of protein structure, formed when interactions among the side groups ($R$ groups) on a polypeptide chain fold it into complex three-dimensional conformations.

Quaternary Protein Structure

The fourth level of protein structure, produced when multiple distinct polypeptide chains (subunits) assemble together into a single functional complex.

Nucleic Acids

The class of macromolecules consisting of DNA and RNA that store, replicate, and transport genetic instructions within the cell.

Nucleotide

The monomer building block of nucleic acids, consisting of three parts: a phosphate group, a 5-carbon sugar, and a nitrogenous base.

Deoxyribonucleic Acid (DNA)

A double-stranded nucleic acid forming a double helix that codes for genetic information and is stored and replicated in the nucleus; contains adenine, thymine, guanine, and cytosine.

Ribonucleic Acid (RNA)

A single-helical nucleic acid synthesized in the nucleus and exported to the cell to transport genetic instructions; replaces thymine with uracil.

Complementary Base Pairing

The specific hydrogen-bonding rule between nitrogenous bases in DNA, where adenine pairs exclusively with thymine ($A\text{--}T$) and guanine pairs with cytosine ($G\text{--}C$).