BIO CHAPTER 3

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 to which an amino group, a carboxyl group, a hydrogen, and an R group is attached.

amphipathic

A molecule with both hydrophobic and hydrophilic parts.

beta-pleated sheet (β-pleated sheet)

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 to oxygen is 1:2:1; serves as energy sources and structural support.

cellulose

Polysaccharide that comprises the plants’ cell wall; provides structural support.

chaperone

Protein that helps nascent protein in the folding process.

chitin

Type of carbohydrate that forms the outer skeleton of arthropods and also forms fungi cell walls.

dehydration synthesis

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.

glycogen

Storage carbohydrate in animals.

glycosidic bond

Bond joining monosaccharides.

hormone

Chemical signaling molecules that are usually small proteins.

hydrolysis

Reaction that causes breakdown of larger molecules into smaller molecules by utilizing water.

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.

nucleotide

Monomer of nucleic acids; contains a pentose sugar, one or more phosphate groups, and a nitrogenous base.

omega fatty acid

Type of unsaturated fatty acid, some of which the body requires in the diet.

peptide bond

Bond formed between two amino acids by a dehydration reaction.

phospholipid

Major constituent of membranes; comprised of two fatty acids and a phosphate-containing group.

polymer

Chain of monomer residues linked by covalent bonds.

polypeptide

Long chain of amino acids linked by peptide bonds.

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

pyrimidine

Type of nitrogenous base in DNA and RNA; cytosine, thymine, and uracil

quaternary structure

Association of discrete polypeptide subunits in a protein.

ribonucleic acid (RNA)

Single-stranded molecule involved in protein synthesis.

ribosomal RNA (rRNA)

RNA that ensures the proper alignment of the mRNA and ribosomes during protein synthesis.

saturated fatty acid

Long-chain hydrocarbon with single covalent bonds in the carbon chain.

secondary structure

Regular structures that proteins form by intramolecular hydrogen bonding.

starch

Storage carbohydrate in plants.

steroid

Type of lipid comprised of four fused hydrocarbon rings.

tertiary structure

A protein’s three-dimensional conformation formed from interactions between amino acid side chains.

transcription

The process by which DNA dictates the structure of RNA.

translation

The process by which mRNA dictates the structure of proteins.

trans fat

Fat formed artificially by hydrogenating oils.

triacylglycerol (triglyceride)

Fat molecule consisting 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.