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Glycosidic bonds
________ are usually formed between a covalently modified sugar and the growing polymer chain.
Biomembranes
________ have a hydrophobic core that separates two aqueous solutions and acts as a permeability barrier.
D 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.
Hydrocarbons
________**- molecules made up only of carbon and hydrogen- are virtually insoluble in water.
Sulphur
________ forms two covalent bonds in hydrogen sulphide (H2S), but also can accommodate six covalent bonds, as in sulfuric acid (H2SO4) and its sulphate derivatives.
Nucleotides
________ are nucleosides that have one, two, or three** phosphate groups** esterified at the 5 hydroxyl.
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)
similar electronegativities
A bond between atoms with identical or ________ is said to be nonpolar.
Nitrogen
________ and phosphorus each have five electrons to share.
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.
tryptophan
Cysteine, ________, and methionine are rare amino acids; together they constitute approximately 5 % of the amino acids in a protein.
Ionic
________ and hydrogen bonds stabilize the interaction of the phospholipid polar head groups with one another and with water.
Arginine
________ and lysine are positively charged; aspartic acid and glutamic acid are negatively charged (their charged forms are called** aspartate** and** glutamate**)
plants
Many species of ________, bacteria, and molds produce cellulose- degrading enzymes.
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.
Mannose
________ is identical with glucose except that the orientation of the groups bonded to carbon 2 is reversed.
inorganic ions
7 % of the weight is living matter composed of ________ and small molecules (amino acids, nucleotides, and sugars)
Fatty acids
________ with no carbon- carbon double bonds are said to be saturated; those with at least one double bond are unsaturated.
Cells
________ and extracellular fluids in organisms contain small concentrations of** nucleosides**, combinations of a base and sugar without a phosphate.
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.
Polysaccharides
________ are linear or branched polymers of monosaccharides (sugars) such as glucose linked by** glycosidic bonds**
steady state
The system of linked reactions for producing and consuming that substance is said to be in a(n) ________.
Hexoses
________ (n= 6) and pentoses (n= 5) are the most common monosaccharides.
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.
hydrogen bonds
Rather than constituting an attractive force such as in ________, the hydrophobic effect results from avoidance of an unstable state (extensive water cages around individual nonpolar molecules)
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.
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.
Adenine
________ and guanine are purines, which contain a pair of fused rings; cytosine, thymine, and uracil are pyrimidines, which contain a single ring.
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.
Human digestive enzymes
________ can hydrolyze the glycosidic bonds in starch, but not the glycosidic bonds in cellulose.
epimerase
The ________ enzymes that interconvert different monosaccharides often do so using the nucleotide sugars rather than the unsubstituted sugars.
Nucleic acids
________ are linear polymers containing hundreds to millions of nucleotides linked by phosphodiester bonds.
Larger polysaccharides
________, 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.
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.
equilibrium constant Keq
The ________ depends on the nature of the reactants and products, the temperature, and the pressure (particularly in reactions involving gases)
Proteins
________ are linear polymers containing ten to several thousand amino acids linked by peptide bonds.
Van der Waals interactions
________**, involving either transiently induced or permanent electric dipoles, occur in all types of molecules, both polar and nonpolar.
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.
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.
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** ________, or R group**
Covalent bonds
________ are very stable because the energies required to break them are much greater than the thermal energy available at room temperature (25oC) or body temperature (37oC)
RNA
In ________, the pentose is ribose; in DNA, it is** deoxyribose**
Membranes
________ literally define what is a cell (the outer ________ and the contents within the ________) and what is not (the extracellular space outside the ________)
Nucleoside monophosphates
________ have a single esterified phosphate, diphosphates contain a pyrophosphate group, triphosphates have the third phosphate.
