The Structure and Function of Large Biological Molecules

Flashcards covering key vocabulary related to the structure and function of large biological molecules, including carbohydrates, lipids, proteins, and nucleic acids.

Macromolecules

Large and complex molecules, including carbohydrates, lipids, proteins, and nucleic acids.

Polymer

A long molecule consisting of many similar building blocks (monomers).

Monomer

The repeating units that serve as building blocks for polymers.

Enzymes

Specialized macromolecules (proteins) that speed up chemical reactions, such as those that make or break down polymers.

Dehydration reaction

A chemical reaction that occurs when two monomers bond together through the loss of a water molecule, synthesizing a polymer.

Hydrolysis

A chemical reaction that disassembles polymers to monomers by adding a water molecule, essentially the reverse of the dehydration reaction.

Carbohydrates

Large biological molecules that include sugars and the polymers of sugars, serving as fuel and building material.

Monosaccharides

The simplest carbohydrates, also known as simple sugars (e.g., glucose).

Polysaccharides

Carbohydrate macromolecules; polymers composed of many sugar building blocks, having storage and structural roles.

Disaccharide

Formed when a dehydration reaction joins two monosaccharides.

Glycosidic linkage

The covalent bond that joins two monosaccharides.

Starch

A storage polysaccharide of plants, consisting entirely of glucose monomers.

Glycogen

A storage polysaccharide in animals, mainly stored in liver and muscle cells.

Cellulose

A major component of the tough wall of plant cells, a polymer of glucose with different glycosidic linkages from starch.

Chitin

A structural polysaccharide found in the exoskeleton of arthropods and the cell walls of many fungi.

Lipids

A diverse group of hydrophobic biological molecules that do not include true polymers and mix poorly with water.

Hydrophobic

A property of lipids, meaning they repel water, due to consisting mostly of hydrocarbons which form nonpolar covalent bonds.

Fats

Lipids constructed from glycerol and fatty acids, primarily functioning in energy storage.

Glycerol

A three-carbon alcohol with a hydroxyl group attached to each carbon, a component of fats.

Fatty acid

Consists of a carboxyl group attached to a long carbon skeleton, a component of fats.

Triacylglycerol (triglyceride)

A fat molecule formed when three fatty acids are joined to glycerol by an ester linkage.

Saturated fatty acids

Fatty acids that have the maximum number of hydrogen atoms possible and no double bonds, typically forming solid saturated fats at room temperature.

Unsaturated fatty acids

Fatty acids that have one or more double bonds, typically forming liquid unsaturated fats (oils) at room temperature.

Hydrogenation

The process of converting unsaturated fats to saturated fats by adding hydrogen.

Trans fats

Unsaturated fats with trans double bonds, created by hydrogenating vegetable oils, potentially contributing to cardiovascular disease.

Essential fatty acids

Unsaturated fatty acids that are not synthesized in the human body and must be supplied in the diet.

Adipose cells

Cells where humans and other mammals store their long-term food reserves as fats, also cushioning organs and insulating the body.

Phospholipid

A lipid in which two fatty acids and a phosphate group are attached to glycerol, forming a hydrophilic head and hydrophobic tails, crucial for cell membranes.

Bilayers

Double-layered structures formed by phospholipids in water, which are fundamental to cell membranes.

Steroids

Lipids characterized by a carbon skeleton consisting of four fused rings (e.g., cholesterol).

Cholesterol

A type of steroid that is a component in animal cell membranes and a precursor from which other steroids are synthesized.

Proteins

Large biological molecules that account for more than 50% of the dry mass of most cells, performing diverse functions from catalysis to structural support.

Amino acids

The building blocks from which all proteins are constructed (20 different types), linked by peptide bonds.

Polypeptides

Unbranched polymers built from amino acids, which fold into a protein structure.

Peptide bonds

Covalent bonds that link amino acids together to form polypeptides.

Primary structure

The unique, linear sequence of amino acids in a protein, determined by inherited genetic information.

Secondary structure

Consists of coils (α helix) and folds (β pleated sheet) in the polypeptide chain, resulting from hydrogen bonds between repeating constituents of the polypeptide backbone.

Tertiary structure

The overall shape of a polypeptide, resulting from interactions among various side chains (R groups), including hydrogen bonds, ionic bonds, hydrophobic interactions, and disulfide bridges.

Quaternary structure

Results when a protein consists of two or more polypeptide chains forming one macromolecule (e.g., hemoglobin, collagen).

Denaturation

The loss of a protein’s native structure due to alterations in physical or chemical conditions (e.g., pH, temperature), rendering it biologically inactive.

Chaperonins

Protein molecules that assist the proper folding of other proteins.

X-ray crystallography

A method used by scientists to determine a protein’s three-dimensional structure.

Nucleic acids

Biological molecules (DNA and RNA) that store, transmit, and help express hereditary information.

Gene

A unit of inheritance consisting of DNA, which programs the amino acid sequence of a polypeptide.

DNA (deoxyribonucleic acid)

A nucleic acid that stores hereditary information, provides directions for its own replication, and directs the synthesis of messenger RNA (mRNA).

RNA (ribonucleic acid)

A nucleic acid, including messenger RNA (mRNA), involved in the process of gene expression and protein synthesis.

Gene expression

The process by which DNA directs the synthesis of mRNA and, through mRNA, controls protein synthesis (DNA → RNA → protein).

Nucleotides

The monomers that make up polynucleotides, each consisting of a nitrogenous base, a pentose sugar, and one or more phosphate groups.

Nucleoside

The portion of a nucleotide without the phosphate group, consisting of a nitrogenous base and a pentose sugar.

Pyrimidines

Nitrogenous bases (cytosine, thymine, and uracil) that have a single six-membered ring.

Purines

Nitrogenous bases (adenine and guanine) that have a six-membered ring fused to a five-membered ring.

Phosphodiester linkage

The covalent bond that links adjacent nucleotides in a polynucleotide, forming a sugar-phosphate backbone.

Double helix

The characteristic structure of DNA molecules, consisting of two polynucleotides spiraling around an imaginary axis.

Antiparallel

Refers to the arrangement of the two sugar-phosphate backbones in a DNA double helix, running in opposite 5′ → 3′ directions.

Complementary base pairing

The specific pairing of nitrogenous bases in DNA (adenine with thymine, guanine with cytosine) and in RNA (adenine with uracil, guanine with cytosine) via hydrogen bonds.

Bioinformatics

The use of computer software and computational tools to deal with and analyze large sets of biological data, such as genome sequences.

Genomics

The analysis of large sets of genes or comparing whole genomes of different species.

Proteomics

The analysis of large sets of proteins, including their sequences.