Structures of Major Compounds in the Body Flashcards
functional groups involve…
oxygen, nitrogen, phosphorus, or sulfur.
Carbohydrates are classified by…
Carbohydrates, commonly known as sugars, can be classified by their carbonyl group (aldo- or ketosugars), the number of carbons they contain (e.g., pentoses, hexoses), or the positions of the hydroxyl groups on their asymmetric carbon atoms (d- or l-sugars, stereoisomers, or epimers). They also can be categorized according to their substituents (e.g., amino sugars) or the number of monosaccharides (such as glucose) joined through glycosidic bonds (disaccharides, oligosaccharides, and polysaccharides).
Lipids are defined by their…
hydrophobicity; they are not very soluble in water.
The organic molecules of the body consist principally of …
carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus joined by covalent bonds.
Groups containing one, two, three, four, and five carbons plus hydrogen are referred to as…
methyl, ethyl, propionyl, butyl, and pentanyl groups, respectively.
If the carbon chain is branched, the prefix…
“iso-” is used
If the compound contains a double bond
“ene” is sometimes incorporated into the name.
Carbon structures that are straight or branched with single or double bonds, but do not contain a ring, are called
aliphatic.
Compounds containing the benzene ring, or a similar ring structure with benzene-like properties, are called…
aromatic.
Biochemical molecules are defined both by their carbon skeleton and by structures called
functional groups
In carbon–carbon and carbon–hydrogen bonds, the electrons are shared
equally between atoms, and the bonds are nonpolar and relatively unreactive
n carbon–oxygen and carbon–nitrogen bonds, the electrons are shared
unequally, and the bonds are polar and more reactive.
Major types of functional groups found in biochemical compounds of the human body
Carbon-Oxygen Groups- Alcohol, Aldehyde, Ketone, Carboxylic Acid, Ether, Acid Anhydride
Carbon- Sulfur Groups- Sulfhydryl group, a disulfide
Carbon- Nitrogen Groups- Amino group and quaternary amine
Esters and Amides- Ester, Thioester, phosphodiester, amide
Oxidation is…
the loss of electrons and results in the loss of hydrogen atoms together with one or two electrons, or the gain of an oxygen atom or hydroxyl group.
Reduction is…
the gain of electrons and results in the gain of hydrogen atoms or loss of an oxygen atom.
Acidic groups contain…
contain a proton that can dissociate, usually leaving the remainder of the molecule as an anion with a negative charge
In biomolecules, the major anionic substituents are…
carboxylate groups, phosphate groups, or sulfate groups (the “-ate” suffix denotes a negative charge)
Compounds that contain nitrogen are usually…
basic and can acquire a positive charge
Amines consist of
nitrogen attached through single bonds to hydrogen atoms and to one or more carbon atoms.
Primary amines…
such as dopamine, have one carbon–nitrogen bond. These amines are weak acids with a pKa value of approximately 9, so that at pH 7.4 they carry a positive charge.
Secondary, tertiary, and quaternary amines have
two, three, and four nitrogen–carbon bonds, respectively
Polar bonds are…
covalent bonds in which the electron cloud is more dense around one atom (the atom with the greater electronegativity) than the other.
In nonpolar carbon–carbon bonds and carbon–hydrogen bonds, the two electrons in the covalent bond are
shared almost equally.
Nitrogen, when it has only three covalent bonds, also carries
partial negative charge relative to carbon, and the carbon–nitrogen bond is polarized
Sulfur can carry a slight partial
negative charge
An ester is formed…
when a carboxylic acid and an alcohol combine, releasing water
a thioester is formed when…
an acid combines with a sulfhydryl group
an amide is formed when
an acid combines with an amine.
Nitrogen is
an electronegative atom with two unshared electrons in its outer valence shell.
At neutral pH, the nitrogen in amino groups is usually
bonded to four other atoms and carries a positive charge
the presence of a nitrogen atom in an organic compound will increase its solubility in…
water, whether the nitrogen is charged or uncharged.
Amino acids are
compounds that contain an amino group and a carboxylic acid group.
In proteins, the amino acids are always…
l-α-amino acids (the amino group is attached to the α-carbon in the l-configuration)
only l-α-amino acids are incorporated into…
proteins
Nitrogen is also a component of ring structures referred to as
heterocyclic rings or nitrogenous bases.
The three most common types of nitrogen-containing rings in the body are…
purines (e.g., adenine), pyrimidines (e.g., thymine), and pyridines (e.g., the vitamins nicotinic acid, also called niacin, and pyridoxine, also called vitamin B6)
The suffix “-ine” denotes the presence of
nitrogen (amine) in the ring. The pyrimidine uracil is an exception to this general type of nomenclature
The utility of these nitrogen-containing ring structures lies in the ability of the nitrogen to form…
hydrogen bonds and to accept and donate electrons while still part of the ring
the unsubstituted aromatic benzene ring, in which electrons are distributed equally among all six carbons is…
nonpolar, hydrophobic, and relatively unreactive.
Nitrogenous bases form
nucleosides and nucleotides
A nucleoside consists of
a nitrogenous base joined to a sugar, usually ribose or deoxyribose, through an N-glycosidic bond
If phosphate groups are attached to the sugar, the compound becomes
a nucleotide
In the name of the nucleotide ATP, the addition of the ribose is indicated by the name change from
adenine to adenosine (for the glycosidic bond).
In many of the nitrogen-containing rings, the hydrogen can shift to produce a…
tautomer
a tautomer is a…
a compound in which the hydrogen and double bonds have changed position (i.e., –N=C–OH → –NH–C=O)
Tautomers are considered the same
compound, and the structure may be represented either way.
Generally, one tautomeric form is more…
reactive than the other. For example, in the two tautomeric forms of uric acid, a proton can dissociate from the enol form to produce urate.
Glycoproteins and proteoglycans have sugars attached to their
protein components.
The major lipids of the human body are…
The major lipids of the human body are the fatty acids, which are esterified to glycerol to form triacylglycerols (triglycerides) or phosphoacylglycerols (phosphoglycerides).
In the sphingolipids, a fatty acid is attached to sphingosine, which is derived from the amino acid
In the sphingolipids, a fatty acid is attached to sphingosine, which is derived from the amino acid serine and another fatty acid.
Glycolipids contain lipids attached to
Glycolipids contain lipids attached to a sugar hydroxyl group.
Specific polyunsaturated fatty acids are precursors of
Specific polyunsaturated fatty acids are precursors of eicosanoids.
The lipid cholesterol is a component of
The lipid cholesterol is a component of membranes and the precursor of other compounds that contain the steroid nucleus, such as the bile salts and steroid hormones.
Cholesterol is one of the compounds synthesized from a….
Cholesterol is one of the compounds synthesized from a five-carbon precursor called the isoprene unit.
Nitrogen in amino groups or heterocyclic ring structures often carries a …
Nitrogen in amino groups or heterocyclic ring structures often carries a positive charge at neutral pH.
Amino acids contain
Amino acids contain a carboxyl group, an amino group, and one or more additional carbons.
Purines, pyrimidines, and pyridines have
heterocyclic nitrogen-containing ring structures. Nucleosides comprise one of these ring structures attached to a sugar.
The addition of a phosphate to a nucleoside produces a…
a nucleotide
