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Chapter 5 - The Structure and Function of Macromolecules

Terms

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Polymer
a long molecule consisting of many identical or similar building blocks linked by covalent bonds
Monomers
small molecules that serve as repeating units that serve as the building blocks of a polymer
Condensation Reaction
the reaction that forms a polymer from multiple monomers by joining two monomers together to form a water molecule; (more specifically this is a dehydration reaction)
Hydrolysis
the process by which polymers are disassembled into smaller units through the addition of water
Carbohydrates
includes sugars and their polymers
Monosaccharides
generally have the molecular formula CH2O; an example is glucose; a hydroxyl group is attached to each carbon except one, which is double-bonded to an oxygen to form a carbonyl group; sugars can be aldoses or ketoses; contains between 3 and 7 carbons in the skeleton
Disaccharides
consist of two monosaccharides joined by a glycosidic linkage, or a covalent bond formed between two monosaccharides by a dehydration reaction
Polysaccharides
macromolecules; polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages
Starch
a storage polysaccharide of plants; it is a polymer consisting entirely of glucose monomers, most joined by 1-4 linkages; starch sugars can be withdrawn as needed through hydrolysis; helical shaped
Glycogen
a polymer of glucose that is similar to some plant starches but much more extensively branched; stored mainly in liver and muscle cells; hydrolysis of glycogen in these cells releases glucose when the demand for sugar increases
Cellulose
A polysaccharide that is a major component of the tough walls that enclose plant cells; straight-shaped
Lipids
Compounds that share little or no affinity for water
Fat
Constructed from glycerol and fatty acids
Glycerol
is an alcohol with a three-carbon skeleton and a hydroxyl group on each carbon
Fatty acid
Second major component of a fat; consists of a carbon skeleton usually 16-18 atoms in length, at one end, there is a carbonyl group.
Triacylglycerol
a fat consisting of three fatty acid chains connected to one glycerol molecule
Saturated fatty acid
refers to the hydrocarbon tail of the fatty acids; if there are no double bonds between any of the carbon molecules in the skeleton, the skeleton will be straight and is referred to as saturated
Unsaturated fatty acid
refers to the hydrocarbon of the fatty acids; has one or more double bonds between the carbons, formed by the removal of hydrogen atoms from the carbon skeleton; this forces a kinked shape in the hydrocarbon skeleton
Phospholipids
similar to fats, but they only have two fatty acids rather than three, the third hydroxyl group in the glycerol molecule is bound to a phosphate group, which is negative in charge, other molecules can be linked to the phosphate; show ambivalence toward water, their tails are hydrophobic and heads are hydrophilic
Steroids
lipids characterized by a carbon skeleton consisting of four fused rings
Cholesterol
is a common component of animal cell membranes and is also the precursor from which other steroids are synthesized; high levels in the blood stream may contribute to atherosclerosis
Proteins
essential to the operations of cellular mechanisms; account for more than 50% of the dry weight of cells; polymers constructed from up to twenty different amino acids; a protein consists of one or more polypeptides folded and coiled into specific conformations
Conformation
three-dimensional shape of a protein; determines a protein’s function, or rather its ability to recognize and bind to some other molecule
Polypeptides
polymers of amino acids
Amino acids
organic molecules that contain a carboxyl group and an amino group; the physical properties of the side chain determine the unique characteristics of the amino acid
Peptide Bond
a covalent bond that is formed as a result of a dehydration reaction between the carboxyl group of one amino acid and the amino group of an adjacent amino acid; a polypeptide is formed from a polymer of many amino acids linked by peptide bonds
Primary structure
the unique sequence of amino acids that form a protein; determined by inherited genetic information; sickle cell anemia is caused by one errant amino acid in the primary structure of the protein hemoglobin
Secondary structure
the coils and folds of the polypeptide chain(s) that are the result of hydrogen bonds at regular intervals along the polypeptide backbone; an alpha helix, for example
Alpha helix
one type of secondary structure; a delicate coil held together by hydrogen bonding every fourth amino acid
Pleated sheet
a type of secondary structure; two regions of the polypeptide chain lie parallel to each other; hair is mostly composed of proteins with pleated sheet secondary structure
Tertiary structure
superimposed over secondary structure lies the tertiary structure, which consists of irregular contortions from bonding between side chains of the various amino acids
Hydrophobic interaction
as a polypeptide folds into its functional conformation, amino acids with hydrophobic (nonpolar) side chains usually congregate in clusters at the core of the protein; water excludes these molecules, van der Walls attraction reinforces these interactions
Disulfuric bridges
strong covalent bonds that reinforce the conformation of a protein; form where two cysteine monomers are brought close together by the folding of the proteins
Quaternary structure
is the overall protein structure that results from the aggregation of these polypeptide subunits
Denaturation
if the pH, salt concentration, temperature, or other aspects of its environment are altered, a protein may unravel and lose its native conformation, which renders the protein biologically inactive
Gene
consists of DNA (a polymer belonging to the class of compounds known as nucleic acids); genes determine the primary structure of proteins
Deoxyribonucleic acid (DNA
provides directions for its own replication; directs RNA synthesis; genetic material that organisms inherit through their parents
Ribonucleic acid (RNA)
directs the synthesis of proteins; DNA→RNA→protein
Nucleotides
monomers that make up DNA; composed of an organic molecule called a nitrogenous base, a pentose (five-carbon sugar), and a phosphate group; two families of nucleotides: pyrimidines and purines
Pyrimidine
a type nucleotide that has a six-membered ring of carbon and nitrogen atoms (which take up H+ from solution); members include cytosine, thymine, and uracil
Purine
a type of nucleotide that has a six member ring fused to a five member ring; members include adenine and guanine
Polynucleotide
a nucleic acid polymer in which nucleotides are joined by covalent bonds called phosphodiester linkages between the phosphate of one nucleotide and the sugar of the next

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