Chapter 2 - Chemical Foundations

Glycosidic bonds

________ are usually formed between a covalently modified sugar and the growing polymer chain.

Glucose

________ (C6H12O6) is the principal external source of energy for most cells in higher organisms and can exist in three different forms: a linear structure and two different.

Asparagine

________ and glutamine are uncharged but have polar side chains containing amide groups with extensive hydrogen- bonding capacities.

fatty acyl chains

The ________ in each leaflet minimize contact with water by aligning themselves.

Large triacylglycerols

________ (or triglycerides), which comprise animal fats and vegetable oils, also are insoluble in water.

Nucleotides

________ are nucleosides that have one, two, or three phosphate groups esterified at the 5 hydroxyl.

Sulfur

________ forms two covalent bonds in hydrogen sulphide (H2S), but also can accommodate six covalent bonds, as in sulfuric acid (H2SO4) and its sulphate derivatives.

Hydrocarbon's molecules

________ made up only of carbon and hydrogen- are virtually insoluble in water.

similar electronegativities

A bond between atoms with identical or ________ is said to be nonpolar.

Arginine

________ and lysine are positively charged; aspartic acid and glutamic acid are negatively charged (their charged forms are called aspartate and glutamate)

Nitrogen

________ and phosphorus each have five electrons to share.

carbon atom

In nucleotides, the 1 ________ of the sugar (ribose or deoxyribose) is attached to the nitrogen at position 9 of a purine (N9) or at position 1 of a pyrimidine (N1)

Ionic

________ and hydrogen bonds stabilize the interaction of the phospholipid polar head groups with one another and with water.

CH2O

Monosaccharides are carbohydrates, which are literally covalently bonded combinations of carbon and water in a one- to- one ratio (________) n, where n equals 3, 4, 5, 6, or 7.

Mannose

________ is identical with glucose except that the orientation of the groups bonded to carbon 2 is reversed.

enzymes

The ________ that make the glycosidic bonds linking monosaccharides into polysaccharides are specific for the or anomer of one sugar and a particular hydroxyl group on the other.

hydroxyl

All monosaccharides contain ________ (OOH) groups and either an aldehyde or a keto group.

X-ray crystallography

________ combined with computational analysis permits an accurate depiction of the distribution of electrons in covalent bonds and the outermost unbonded electrons of atoms.

inorganic ions

7 % of the weight is living matter composed of ________ and small molecules (amino acids, nucleotides, and sugars)

Fatty acids

________ containing 12 or more carbon atoms are nearly insoluble in aqueous solutions because of their long hydrophobic hydrocarbon chains.

Polysaccharides

________ are linear or branched polymers of monosaccharides (sugars) such as glucose linked by glycosidic bonds.

glycogen

Both ________ and starch are composed of the anomer of glucose.

spherical micelles

When a suspension of phospholipids is mechanically dispersed in an aqueous solution, the phospholipids aggregate into one of three forms: ________ and liposomes and sheetlike, two- molecule- thick phospholipid bilayers.

guanine

The bases adenine, ________, and cytosine are found in both DNA and RNA; thymine is found only in DNA, and uracil is found only in RNA.

steady state

The system of linked reactions for producing and consuming that substance is said to be in a(n) ________.

DNA

The monomers from which ________ and RNA are built, called nucleotides, all have a common structure: a phosphate group linked by a phosphodiester bond to a pentose (a five- carbon sugar molecule) that in turn is linked to nitrogen- and carbon- containing ring structure commonly referred to as a "base.

Hexoses

________ (n= 6) and pentoses (n= 5) are the most common monosaccharides.

Adenine

________ and guanine are purines, which contain a pair of fused rings; cytosine, thymine, and uracil are pyrimidines, which contain a single ring.

hydrogen bonds

There are four major types of noncovalent interactions: ionic interactions, ________, van der Waals interactions, and the hydrophobic effect.

rigid planarity

The ________ imposed by double bonds has enormous significance for the shapes and flexibility of large biological molecules such as proteins and nucleic acids.

Micelles

________ are rarely formed from natural phosphoglycerides, whose fatty acyl chains generally are too bulky to fit into the interior of a(n) ________.

Disulphide bonds

________ are commonly found in extracellular proteins, where they help stabilize the folded structure.

OOH bonds

Because of its two ________, water molecules (H2O) are dipoles that form electrostatic, noncovalent interactions with one another and with other molecules.

core

Because of their hydrophobic ________, bilayers are virtually impermeable to salts, sugars, and most other small hydrophilic molecules.

nucleic acids

Unlike the proteins, ________, and polysaccharides, membranes are assembled by the noncovalent association of their component building blocks.

Human digestive enzymes

________ can hydrolyze the glycosidic bonds in starch, but not the glycosidic bonds in cellulose.

polar covalent bond

A(n) ________ in one molecule will attract an oppositely oriented dipole in another.

polysaccharides

Larger ________, containing dozens to hundreds of monosaccharide units, can function as reservoirs for glucose, as structural components, or as adhesives that help hold cells together in tissues.

epimerase

The ________ enzymes that interconvert different monosaccharides often do so using the nucleotide sugars rather than the unsubstituted sugars.

Amino acids

________ with polar side chains are hydrophilic and tend to be on the surfaces of proteins; by interacting with water, they make proteins soluble in aqueous solutions and can form noncovalent interactions with other water- soluble molecules.

exert different attractions for

Many molecules, the bonded atoms ________ the electrons of the covalent bond, resulting in unequal sharing of the electrons.

Biomembranes

________ are large flexible sheets that serve as the boundaries of cells and their intracellular organelles and form the outer surfaces of some viruses.

Proteins

________ are linear polymers containing ten to several thousand amino acids linked by peptide bonds.

aldehyde group

If the ________ on carbon 1 reacts with the hydroxyl group on carbon 5, the resulting hemiacetal, D- glucopyranose, contains a six- member ring.

hydrogen atom

A(n) ________ forms only one bond.

Van der Waals interactions

________, involving either transiently induced or permanent electric dipoles, occur in all types of molecules, both polar and nonpolar.

side chain

The monomeric building blocks of proteins are 20 amino acids, all of which have a characteristic structure consisting of a central carbon atom (C) bonded to four different chemical groups: an amino (NH2) group, a carboxyl (COOH) group, hydrogen (H) atom, and one variable group, called a(n) ________, or R group.

nonspecific attractive force

When any two atoms approach each other closely, they create a weak, ________ called a van der Waals interaction.

RNA

In ________, the pentose is ribose; in DNA, it is deoxyribose.

functions of biomolecules

The weak attractive forces of noncovalent interactions are equally important in determining the properties and ________ such as proteins, nucleic acids, carbohydrates, and lipids.