chapter 7 pt 1 Flashcards
what is energy?
fuel for most organisms
-colorless, crystalline solids that are freely soluble in water due to many OH groups but insoluble in nonpolar solvents
-multiple asymmetric (chiral) carbons
-2^n stereoisomers
-general formula (CH2O)n
Monosaccharides
monosaccharides with two or more hydroxyl groups
aldehydes or ketones
two families of monosaccharides
aldoses & ketoses (usually at C2)
backbones of common monosaccharides
unbranched carbon chains where all the carbon atoms are linked by single bonds
describe open chain form of monosaccharides
one of the carbon atoms is double-bonded to an oxygen atom to form a carbonyl group; other carbon atoms have a hydroxyl group
when the carbonyl group is at an end of the carbon chain
the monosaccharide is an aldose
when the carbonyl group is at any other position (not the end)
the monosaccharide is a ketose
what are the simplest monosaccharides?
2 three-carbon trioses:
glyceraldehyde, an aldotriose, & dihydroxyacetone, a ketotriose
biological length of monosaccharides
3 to 9 carbons (5 & 6 most common) and unbranched
what does n equal in 2^n stereoisomers?
n = # of chiral carbons
monosaccharides with 4, 5, 6, & 7 carbon atoms in backbones are called
tetroses, pentoses, hexoses, and heptoses
hexoses of monosaccharides
aldohexose D-glucose, ketohexose D-fructose
components of nucleotides and nucleic acids
aldopentoses of D-ribose, 2 deoxy-D-ribose
what type of centers do monosaccharides have?
-asymmetric centers
-they contain one or more asymmetric (chiral) carbon atoms and occur in optically active isomeric forms
simplest aldose that contains one chiral center (middle carbon atom) and two different optical isomers
glyceraldehyde
two different optical isomers; mirror images of each other
enantiomers
when the hydroxyl group on the reference carbon is on the right (with the carbonyl carbon at the top) then the sugar is a ?
-D isomer
-Most organisms have D isomers
L-glyceraldehyde
D-glyceraldehyde
monosaccharide that has achiral carbon
dihydroxyacetone
differ in 1 or more chiral centers
diastereomers
differ at only 1 carbon
epimers
what are glycoconjugates?
complex carbohydrate polymers covalently attached to proteins or lipids that act as signals that determine the intracellular destination or metabolic fate of these hybrid molecules
What is a carbohydrate?
polyhydroxy aldehydes or ketones or substances that yield such compounds on hydrolysis
3 major classes of carbohydrates
-monosaccharides
-oligosaccharides
-polysaccharides
-consists of short chains of monosaccharide units or residues joined by characteristic linkages called glycosidic bonds
-most common form is dissacharides - with two monosaccharide units
Oligosaccharides
what suffix do common monosaccharides and disaccharides have?
common names ending with the suffix “-ose”
sugar polymers containing more than 20 or so monosaccharides
Polysaccharides
when the hydroxyl group is on the left then its an ?
L isomer
Fischer projection of ?
D-glucose
How are carbons numbered?
carbons of a sugar are numbered beginning at the end of the atom nearest the carbonyl group
what types of structures do common monosaccharides have?
cyclic structures
ring structure formation of monosaccharides usually form derivatives called
hemiacetals or hemiketals
what are hemiketals?
addition to a ketose
what are hemiacetals?
addition to an aldose
what bond is formed in a hemiacetal or hemiketal?
glycosidic linkage
what acetal or ketal is formed when the two molecules that react are monosaccharides?
disaccharide
isomeric forms of monosaccharides that differ only in their configuration about the hemiacetal or hemiketal carbon atom are called
anomers (carbonyl carbon atom is called anomeric carbon)
six membered ring compounds
pyranoses
stereoisomeric configurations (used for Haworth projection)
alpha, beta
what type of monosaccharide is pyranose?
aldose
what type of monosaccharide is furanose?
ketose
cyclization of glucose & fructose & alcohol & carbonyl forms a ?
cyclic hemiacetal
alpha and beta anomers interconverting in solution due to spontaneous reversible ring opening/ closing (either alpha or beta configuration at C1)
mutarotation
if the OH on C1 is on top, then its ?
beta
if the OH on C1 is down, then its ?
alpha
When drawing the Haworth projection, anything to the left is drawn ____ and anything to the right is drawn ______
up; down
the terminal in the Haworth projection, CH2OH, is up for _____ isomers and down for ______ isomers
D; L
Monosaccharides are _____ agents
reducing
Monosaccharides can be oxidized by relatively mild oxidizing agents such _____ ion (carbonyl group is oxidized to a carboxyl group)
cupric (Cu 3+)
sugars capable of reducing cupric ions (such as glucose)
reducing sugars
Disaccharides contain a _____ bond
glycosidic
Disaccharides consist of two monosacchraides formed covalently by an ____
O-glycosidic bond
How is an O-glycosidic bond formed?
when a hydroxyl group of one sugar molecule reacts with the anomeric carbon of the other (forms a glycoside0 (C1-C4 bonds)
important Hexose derivatives:
Glc =
Fru =
Gal =
Man =
Rib =
Xyl =
GlcN =
GlcNAc =
GalN =
GalNAc =
GlcA =
GlcUA =
glucose
fructose
galactose
mannose
ribose
xylose
glucosamine
N-acetylglucosamine
galactosamine
N-acetylgalactosamine
gluconic acid
glucuronic acid
