Chapter 5

Polysaccharides

A polymer of many monosaccharides, formed by dehydration reactions.

Purines

one of two types of nitrogenous bases found in nucleotides, characterized by a six-membered ring fused to a five-membered ring. adenine (a) and guanine (G).

fatty acid

A carboxylic acid with a long carbon chain. Fatty acids vary in length and in the number and location of double bonds; three fatty acids linked to a glycerol molecule form a fat molecule, also known as a triacylglycerol or triglyceride.

dehydration reaction

A chemical reaction in which two molecules become covalently bonded 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.

glycosidic linkage

A covalent bond formed between two monosaccharides by a dehydration reaction.

gene

A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses).

disaccharide

A double sugar, consisting of two monosaccharides joined by glycosidic linkage formed by dehydration synthesis.

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 that has one or more double bonds between carbons in the hydrocarbon tail. Such bonding reduces the number of hydrogen atoms attached to the carbon skeleton.

macromolecules

A giant molecule formed by the joining of smaller molecules, usually by a dehydration reaction. ex. carbohydrates, proteins, and nucleic acids

triacylglycerol

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

fat

A lipid consisting of three fatty acids linked to one glycerol molecule; also called a triacylglycerol or triglyceride.

phospholipid

A lipid made up of a glyerol joined to two fatty acids and a phosphate group; has two hydrophobic tails and a polar, hydrophilic head

Cholesterol

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

polymer

A long molecule consisting of many similar or identical monomers linked together.

enzymes

A macromolecule serving as a catalyst, a chemical agent that increases the rate of a reaction without being consumed by the reaction. Most enzymes are proteins.

deoxyribonucleic acid (DNA)

A nucleic acid molecule, usually a double-stranded helix, in which each polynucleotide strand consists of nucleotide monomers with a deoxyribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and thymine (T); capable of being replicated and determining the inherited structure of a cell's proteins.

polynucleotides

A polymer consisting of many nucleotide monomers in a chain; nucleotides can be those of DNA or RNA.

Nucleic acids

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

starch

A storage polysaccharide in plants consisting entirely of glucose monomers joined by glycosidic linkages

chitin

A structural polysaccharide, consisting of amino sugar monomers, found in many fungal cell walls and in the exoskeletons of all arthropods.

Carbohydrates

A sugar (monosaccharide) or one of its dimers (disaccharide) or polymers (polysaccharide)

Steroids

A type of lipid characterized by a carbon skeleton consisting of four rings with various functional groups attached.

ribonucleic acid (RNA)

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.

Which functional group(s) is (are) present in all amino acids?

An amino acid has an amino group (−NH2−NH2) and a carboxyl group (−COOH−COOH).

glycogen

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

trans fats

An unsaturated fat, formed artificially during hydrogenation of oils, containing one or more trans double bonds.

lipids

Any of a group of large biological molecules, including fats, phospholipids, and steroids, that mix poorly, if at all, with water.

The four main categories of large biological molecules present in living systems are _____. See Concept 5.1 A. nucleic acids, carbohydrates, monosaccharides, and proteins B. proteins, nucleic acids, carbohydrates, and lipids C. RNA, DNA, proteins, and carbohydrates D. proteins, DNA, RNA, and steroids E. monosaccharides, lipids, polysaccharides, and proteins

B. proteins, nucleic acids, carbohydrates, and lipids

A dehydration reaction (or condensation reaction) is the process in which _____. See Concept 5.1 (Page 67) A. the bonds between the individual monomers of a polymer are broken by the addition of water molecules B. water molecules are produced as a polymer is formed from monomers C. water molecules are used as a source of raw material to break down polymers to monomers D. water molecules are attracted to each other E. None of the choices is correct.

B. water molecules are produced as a polymer is formed from monomers Monomers are joined together in a reaction in which two molecules are covalently bonded to each other through the loss of a water molecule; this is called a condensation reaction or, specifically, a dehydration reaction.

Starch is composed of ________. A. branched amylopectin and branched amylose B. unbranched amylopectin and unbranched amylose C. branched amylopectin and unbranched amylose D. unbranched amylopectin and branched amylose

C. branched amylopectin and unbranched amylose

What component of amino acid structure varies among different amino acids? A, the long carbon-hydrogen tails of the molecule B. the glycerol molecule that forms the backbone of the amino acid C. the components of the R group D. the presence of a central C atom

C. the components of the R group

The characteristic that all lipids have in common is that _____. See Concept 5.3 (Page 72) A. they are all made of fatty acids and glycerol B. they do not have a high energy content C. they are all acidic when mixed with water D. they all contain nitrogen E. none of them dissolves in water

E. none of them dissolves in water Almost all the covalent bonds in lipids are nonpolar, causing their solubility in water to be extremely low. Lipids are hydrophobic substances.

The building blocks or monomers of nucleic acid molecules are called _____. See Concept 5.5 (Page 84) A. pyrimidines and purines B. polysaccharides C. DNA and RNA D. fatty acids E. nucleotides

E. nucleotides A nucleotide is a nucleic acid monomer consisting of a nitrogen base, a pentose sugar, and a phosphate group. Nucleotides joined together by covalent bonds called phosphodiester linkages form nucleic acid molecules.

pyrimidine

One of two types of nitrogenous bases found in nucleotides, characterized by a six-membered ring. Cytosine (C), thymine (T), and uracil (U) are pyrimidines.

nucleotides

The building block of a nucleic acid, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and one to three phosphate groups.

double helix

The form of native DNA, referring to its two adjacent polynucleotide strands wound into a spiral shape.

gene expression

The process by which information encoded in DNA directs the synthesis of proteins or, in some cases, RNAs that are not translated into proteins and instead function as RNAs.

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.

monomers

The subunit that serves as the building block of a polymer.

deoxyribose

The sugar component of DNA nucleotides, having one fewer hydroxyl group than ribose, the sugar component of RNA nucleotides.

ribose

The sugar component of RNA nucleotides.

bioinformatics

The use of computers, software, and mathematical models to process and integrate biological information from large data sets.

cellulose

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

antiparallel

referring to the arrangement of the sugar-phosphate backbones in a DNA double helix (they run in opposite 5' -3' directions).

proteomics

the systematic study of sets of proteins and their properties, including their abundance, chemical modifications, and interactions

genomics

the systematic study of whole sets of genes (or other DNA) and their interactions within a species, as well as genome comparisons between species