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of plants; it is a polymer consisting entirely of glucose monomers, most joined by 1-4 linkages; starch sugars can be withdrawn as needed through hydrolysis; helical shaped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