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The Structure and Function of Large Biological Molecules

macromolecules

A giant molecule in a living organism formed by the joining of smaller molecules: a protein, carbohydrate, or nucleic acid.

polymer

a long molecule consisting of many similar or identical building blocks linked by covalent bonds

monomers

repeating units that serve as the building blocks of a polymer

enzymes

specialized macromolecules that speed up chemical reactions in cells

dehydration reaction

A chemical reaction in which two molecules covalently bond to each other with the removal of a water molecule.

hydrolysis

A chemical reaction that breaks bonds between two molecules by the addition of water; functions in disassembly of polymers to monomers.

carbohydrates

Organic compounds composed of carbon, hydrogen, and oxygen in a ratio of one carbon atom to two hydrogen atoms to one oxygen atom. They exist as monosaccharides, disaccharides, and polysaccharides.

monosaccharides

The simplest carbohydrate, active alone or serving as a monomer for disaccharides and polysaccharides. Also known as simple sugars, the molecular formulas of are generally some multiple of CH2O.

aldose

a monosaccharide sugar that contains the aldehyde group or is hemiacetal

ketose

any monosaccharide sugar that contains a ketone group or its hemiacetal

disaccharide

any of a variety of carbohydrates that yield two monosaccharide molecules on complete hydrolysis

glycosidic linkage

A covalent bond formed between two monosaccharides by a dehydration reaction. - sucrose, glucose

polysaccharides

macromolecules, polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages - starch, cellulose

starch

A storage polysaccharide in plants consisting entirely of glucose.

glycogen

an extensively branched glucose storage polysaccharide found in the liver and muscle of animals; the animal equivalent of starch

cellulose

a structural polysaccharide of plant cell walls, consisting of glucose monomers joined by β glycosidic linkages.

chitin

complex carbohydrate that makes up the cell walls of fungi; also found in the external skeletons of arthropods

lipids

Large, non-polar organic molecules which do not dissolve in water. - fats, phospholipids, steroids, waxes.

fat

organic compound consisting of a three-carbon backbone (glycerol) attached to three fatty acids

fatty acids

A long carbon chain carboxylic acid. Fatty acids vary in length and in the number and location of double bonds; three fatty acids linked to a glycerol molecule form fat.

triacylglycerol

three fatty acids linked to one glycerol molecule; also called a fat or a triglyceride.

saturated fatty acid

A fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds, thus maximizing the number of hydrogen atoms that can attach to the carbon skeleton.

unsaturated fatty acid

a fatty acid whose carbon chain can absorb additional hydrogen atoms

trans fats

made by hydrogenating unsaturated fats, considered "bad fats"; can lead to clogged arteries

phospholipids

A molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail.

steroids

lipids characterized by a carbon skeleton consisting of four fused rings

cholesterol

A steroid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis of other biologically important steroids.

catalyst

substance that speeds up the rate of a chemical reaction

polypeptide

hundreds of amino acids bonded together in a long chain, sequence of amino acids determines protein

protein

A functional biological molecule consisting of one or more polypeptides folded and coiled into a specific three-dimensional structure.

enzymatic proteins

selective acceleration of chemical reactions
ex. digestive enzymes

storage proteins

Function: storage of amino acids (ex - casein in milk, ovalbumin in egg whites)

defensive proteins

protection against disease
ex. antibodies

transport proteins

Proteins that combine with other substances and acts as a mode of transport through the body (e.g. albumin, hemoglobin, transferrin, and vitamin d-binding protein).

hormonal proteins

Function: coordination of an organism's activities.
(ex - insulin causes other tissues to take up glucose)

receptor proteins

Function: response of cell to chemical stimuli (ex - nerve cell receptors detect signaling molecules)

motor proteins

protein that interacts with cytoskeletal elements and other cell components, producing movement of the whole cell or parts of the cell - cilia, flagella, actin and myosin proteins

structural proteins

very important in binding structures together and providing strength in certain body tissues, Keratins, collagens, and cytoskeleton, Proteins that are important for holding cells and organisms together, such as the proteins that make up the cell membrane, muscles, tendons, and blood

amino acid

monomer that makes up proteins; contains carboxyl and amino functional groups - 20

peptide bond

the covalent bond between two amino acid units in a polypeptide, formed by a dehydration reaction

primary structure

The first level of protein structure; the specific sequence of amino acids making up a polypeptide chain.

secondary structure

Alpha helix and beta pleated sheet formed through formation of hydrogen bonds., The second level of protein structure; the regular local patterns of coils or folds of a polypeptide chain.

tertiary structure

the third level of protein structure; the overall, three-dimensional shape of a polypeptide due to interactions of the R groups of the amino acids making up the chain

quaternary structure

The fourth level of protein structure; the shape resulting from the association of two or more polypeptide subunits

sickle-cell disease

A human genetic disease caused by a recessive allele that results in the substitution of a single amino acid in a globin polypeptide that is part of the hemoglobin protein; characterized by deformed red blood cells (due to protein aggregation) that can

denaturation

For proteins, a process in which a protein unravels and loses its native conformation, thereby becoming biologically inactive. For DNA, the separation of the two strands of the double helix. Denaturation occurs under extreme conditions of pH, salt concentration, and temperature.

chaperonins

Protein molecules that assist the proper folding of other proteins; they work by keeping the new polypeptide segregated from bad influences in the cytoplasmic environment while it folds spontaneously

X-ray crystallography

a laboratory technique that is used to determine the three-dimensional structure of biological molecules such as proteins and DNA

nuclear magnetic resonance spectroscopy

Technique used for determining the three-dimensional structure of a protein. It is performed in solution without requiring a protein crystal.

gene

sequence of DNA that codes for a protein and thus determines a trait

nucleic acids

Polymers assembled from individual nucleotides; used to store and transmit hereditary, or genetic, information; the two kinds of nucleic acids are ribonucleic acid (RNA) and deoxyribonucleic acid (DNA)

deoxyribonucleic acid

A nucleic acid found in all living cells which carries the organism's hereditary information

ribonucleic acid

A type of nucleic acid consisting of nucleotide monomers with a ribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and uracil (U); usually single-stranded; functions in protein synthesis and as the genome of some viruses.

polynucleotides

A polymer consisting of many nucleotide monomers; serves as a blueprint for proteins and, through the actions of proteins, for all cellular activities. The two types are DNA and RNA

nucleotides

monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base

nucleoside

portion of nucleotide without phosphate group

pyramidine

Six-membered ring of carbon and nitrogen; includes cytosine (C), thymine (T), and uracil (U)

purines

the family of larger nitrogenous bases in which its members have a six-membered ring fused to a five-membered ring; members are adenine (A) and guanine (G)

deoxyribose

a five carbon sugar that is a component of DNA nucleotides

ribose

a pentose sugar important as a component of ribonucleic acid

double helix

a pair of parallel helices intertwined about a common axis, esp. that in the structure of the DNA molecule

antiparallel

The opposite arrangement of the sugar-phosphate backbones in a DNA double helix.

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