Flashcards in Chapter 4- Carbohydrate Structure and Function Deck (37)
trioses- 3 carbons
tetroses- 4 carbons
pentoses- 5 carbons
hexoses- 6 carbons
carbohydrates that contain an aldehyde group as their most oxidized functional group
carbohydrates that contain a ketone group as their most oxidized functional group
simplest aldose sugar
glyceraldehyde (aka. aldotriose)
which carbon is typically the most oxidized
the carbonyl carbon (attached to the doublebonded O)
sugars acting as substituents (typically aldehyde carbon)
simplest ketone sugar (ketose). carbonyl carbon is most oxidized (carbonyl carbon is usually C2)
optical isomers. compounds that have the same chemical formula (only differ from one another in terms of spatial arrangement)
same molecular formula
mirror images of each other.
any molecule that contains chiral carbons and no internal planes of symmetry.
number of stereoisomers with common backbone
2^n (n = number of chiral carbons in the molecule)
horizontal lines (wedges)-- out of page (right side pointing down)
vertical lines (dashed)-- into page
same molecular formula
not mirror images
subtype of diastereomers that differ in configuration at exactly one chiral center (ex: D-ribose and D-arabinose)
most common electrophile
carbonyl group (C doublebonded to O)
pyranose and furanose rings
pyranose- 6C rings
furanose- 5C rings
rings are typically hemiacetals or hemiketals
what happens when you expose a hemiacetal ring to water?
they will spontaneously cycle b/w open and closed form
interconversion between anomers of a compound (ex: a and B conformations)
spontaneous change of configuration about C-1 and occurs more rapidly when the reaction is catalyzed with an acid or base.
reactions that monosaccharides can undergo and why
b/c they contain alcohols and either aldehydes or ketones they can undergo....
3. nucleophilic attack (creating glycosides- sugar bound to another functional group)
the aldehyde group of a monosaccharide is oxidized to a carboxylic acid. this oxidized aldose (reducing agent) is called an aldonic acid.
any monosaccharide with a hemiacetal ring
cyclic ester. when aldose being oxidized is in ring formation then the oxidation yields a lactone. (ex: vitamin C)
how to detect the presence of reducing sugars?
Tollen's reagent: uses Ag(NH3)2+ as oxidizing agent. so aldehydes reduce Ag+ to metallic silver
Benedict's reagent: aldehyde group of an aldose is readily oxidized by Cu(OH)2, indicated by a red precipitate of Cu2O
*note: ketose sugars are also reducing sugars and give positive test results for these.
rearrangement of bonds in a compound, usually by moving a hydrogen and forming a double bond.
compound with a double bond and an alcohol group
formed when the aldehyde group of an aldose is reduced to an alcohol
contains a hydrogen that replaces a hydroxyl group on the sugar (most well known is the deoxyribose which is the carbohydrate found in DNA)
carbohydrates have hydroxyl groups which can react with carboxylic acids and their derivatives to form esters. (most important reaction in body is the phosphorylation of glucose to form a phosphate ester, this uses hexokinase or glucokinase as an enzyme)
formed when hemiacetals (hemiketals) react with alcohols under acidic conditions, resulting C-O bonds are called glycosidic bonds and the acetals (ketals) formed are glycosides --dehydration reaction
furanosides and pyranosides
glycosides derived from furanose and pyranose rings, respectively -- dehydration reaction