24 Key Terms
- active site
- location on an enzyme configured to bind a substrate
- alpha-helix structure (α-helix)
- type of secondary protein structure formed by folding the polypeptide into a helix shape with hydrogen bonds stabilizing the structure
- amino acid
- a protein’s monomer; has a central carbon or alpha carbon to which an amino group, a carboxyl group, a hydrogen, and an R group or side chain are attached; the R group is different for all 20 common amino acids
- beta-pleated sheet (β-pleated)
- secondary structure in proteins in which hydrogen bonding forms “pleats” between atoms on the polypeptide chain’s backbone
- biological macromolecule
- large molecule necessary for life that is built from smaller organic molecules
- carbohydrate
- biological macromolecule in which the ratio of carbon to hydrogen and to oxygen is 1:2:1; carbohydrates serve as energy sources and structural support in cells and form arthropods’ exoskeleton
- cellulose
- polysaccharide that comprises the plant’s cell wall; provides structural support to the cell
- chaperone
- (also, chaperonin) protein that helps nascent protein in the folding process
- chitin
- type of carbohydrate that forms the outer skeleton of all arthropods including crustaceans and insects; it also forms fungi cell walls
- chromatin
- complex of histone proteins and DNA, the substance of eukaryotic chromosomes
- chromosome
- structure composed of DNA and histone proteins, containing genetic information
- dehydration synthesis
- (also, condensation) reaction that links monomer molecules, releasing a water molecule for each bond formed
- denaturation
- loss of shape in a protein as a result of changes in temperature, pH, or chemical exposure
- deoxyribonucleic acid (DNA)
- double-helical molecule that carries the cell’s hereditary information
- disaccharide
- two sugar monomers that a glycosidic bond links
- enzyme
- catalyst in a biochemical reaction that is usually a complex or conjugated protein
- genome
- a cell or organism’s entire genetic content
- glycogen
- storage carbohydrate in animals
- glycosidic bond
- bond formed by a dehydration reaction between two monosaccharides, involving eliminating a water molecule
- hormone
- chemical signaling molecule, usually protein or steroid, secreted by endocrine cells that act to control or regulate specific physiological processes
- hydrolysis
- reaction that causes breakdown of larger molecules into smaller molecules by utilizing water
- hydrolysis reactions
- breaking a large molecule into smaller molecules by adding and splitting a water molecule
- lipid
- macromolecule that is nonpolar and insoluble in water
- messenger RNA (mRNA)
- RNA that carries information from DNA to ribosomes during protein synthesis
- monomer
- smallest unit of larger molecules that are polymers
- monosaccharide
- single unit or monomer of carbohydrates
- nucleic acid
- biological macromolecule that carries the cell’s genetic blueprint and carries instructions for the cell’s functioning
- nucleotide
- monomer of nucleic acids; contains a pentose sugar, one or more phosphate groups, and a nitrogenous base
- omega fat
- type of polyunsaturated fat that the body requires; numbering the carbon, omega starts from the methyl end, or the end that is farthest from the carboxylic end
- peptide bond
- bond formed between two amino acids by a dehydration reaction
- phosphodiester
- linkage covalent chemical bond that holds together the polynucleotide chains with a phosphate group linking neighboring nucleotides’ two pentose sugars
- phospholipid
- membranes’ major constituent; comprised of two fatty acids and a phosphate-containing group attached to a glycerol backbone
- polymer
- chain of monomers that covalent bonds link; polymerization is the process of polymer formation from monomers by condensation
- polynucleotide
- long chain of nucleotides
- polypeptide
- long chain of amino acids that peptide bonds link
- polysaccharide
- long chain of monosaccharides; may be branched or unbranched
- primary structure
- linear sequence of amino acids in a protein
- protein
- biological macromolecule comprised of one or more amino acid chains
- purine
- type of nitrogenous base in DNA and RNA; adenine and guanine are purines
- pyrimidine
- type of nitrogenous base in DNA and RNA; cytosine, thymine, and uracil are pyrimidines
- quaternary structure
- arrangement of polypeptide subunits within a protein that has multiple subunits
- ribonucleic acid (RNA)
- single-stranded, often internally base paired, molecule that is involved in protein synthesis
- ribosomal RNA (rRNA)
- RNA that ensures the proper alignment of mRNA and ribosomes during protein synthesis and catalyzes formation of the peptide linkage
- saturated fatty acid
- long-chain hydrocarbon with single covalent bonds in the carbon chain; the number of hydrogen atoms attached to the carbon skeleton is maximized
- secondary structure
- regular structure that proteins form by intramolecular hydrogen bonding between the oxygen atom of one amino acid and the hydrogen attached to the nitrogen atom of another
- starch
- storage carbohydrate in plants
- steroid
- type of lipid comprised of four fused hydrocarbon rings forming a planar structure
- tertiary structure
- a protein’s three-dimensional conformation, including interactions between secondary structural elements; formed from interactions between amino acid side chains
- trans fat
- fat formed artificially by hydrogenating oils, leading to a different arrangement of double bond(s) than those in naturally occurring lipids
- transcription
- process through which messenger RNA forms on a template of DNA
- transfer RNA (tRNA)
- RNA that carries activated amino acids to the site of protein synthesis on the ribosome
- translation
- process through which RNA directs the protein’s formation
- triacylglycerol (also, triglyceride)
- fat molecule; consists of three fatty acids linked to a glycerol molecule
- unsaturated fatty acid
- long-chain hydrocarbon that has one or more double bonds in the hydrocarbon chain
- wax
- lipid comprised of a long-chain fatty acid that is esterified to a long-chain alcohol; serves as a protective coating on some feathers, aquatic mammal fur, and leaves
