Carbohydrates Flashcards
What is the most basic structural unit of carbohydrates?
monosaccharides
What is the simplest monosaccharide?
trioses
What are aldoses?
carbohydrates that contain an aldehyde group as their most oxidized functional group
What are ketoses?
carbohydrates that contain a ketone group as their most oxidized functional group
Structure of D-fructose
google it
Structure of D-glucose
google it
Structure of D-galactose
google it
Structure of D-mannose
google it
What are stereoisomers?
compounds that have the same chemical formula but differ in spatial arrangement of atoms
What are enantiomers?
stereoisomers that are non-identical, nonsuperimposable mirror images of each other
Equation for number of stereoisomers
2^n
What are diasteroemers?
stereoisomers that are non identical and not mirror images
What are epimers?
diastereoisomers that differ in configuration at exactly on chiral center
What is a six membered ring called?
furanose
What is a five membered ring called?
pyranose
What is an alpha -anomer?
when the -OH group of C-1 is trans to the CH2OH group (axial and down)
What is a beta-anomer?
when then -OH group of C-1 is cis to the CH2OH group (equatorial and up)
What is mutarotation?
spontaneous change of configuration about C-1 and is catalyzed with acid or base; results in a mixture of both alpha and beta anomers
What are aldonic acids?
oxidized aldoses
What are lactones?
a cyclic ester with a carbonyl group
What are two reagents used to test the presence of a reducing sugar?
Tollen’s reagent and Benedict’s reagent
What is Tollen’s reagent?
silver nitrate + NaOH –> silver oxide + ammonia –> Tollen’s reagent
How does Benedict’s reagent work?
aldehyde group of aldose is readily oxidized and a red precipitate is formed
What is tautomerization?
refers to the rearrangement of bonds in a compound, usually moving a hydrogen, and forming a double bond
What is an enol?
a compound with a double bond and alcohol group
What is an alditol?
when the aldehyde group of an aldose is reduced to an alcohol
What is a deoxy sugar?
contains a hydrogen that replaces a hydroxyl group on the sugar
What is phosphorylation of glucose?
metabolic reaction of glycolysis in which a phosphate group is transferred from ATP to glucose, thus phosphorylating glucose while forming ADP
What is the difference between esterification and glycoside formation?
Esterification is the reaction by which a hydroxyl group reacts with either a carboxylic acid or a carboxylic acid derivative to form an ester; glycoside formation refers to the reaction between an alcohol and a hemiactal/ketal group on a sugar to yield an alkoxy group
Do carbs get oxidized or reduced?
oxidized
What is a disaccharide?
glycosidic bonds formed between hydroxyl groups of two monosaccharides
Structure of sucrose
google it
Structure of lactose
google it
Structure of maltose
google it
What are polysaccharides?
long chains of monosaccharides linked together by glycosidic bonds
What is a polysaccharide made entirely of glucose?
homopolysaccharide
What is cellulose?
homopolysaccharide - a chain of beta-D-glucose molecules linked by beta-1,4 glycosidic bonds, with hydrogen bonds holding the actual polymer chains together for support
What are starches?
polysaccharides that are more digestible by humans because they are linked alpha-D-glucose monomers
What is amylose?
linear glucose polymer linked via alpha-1,4 glycosidic bonds (plants store starch as this)
What reagent tests for the presence of starch?
iodine
What does beta-amylase do?
cleaves amaylose at the nonreducing end of the polymer (the end with the acteal) to yield maltose
What does alpha-amylase do?
cleaves randomly along the chain to yield shorter polysaccharide chains, maltose and glucose
What is glycogen?
carbohydrate storage for animals -
What is glycogen phosphorylase?
functions by cleaving glucose from the nonreducing end of a glycogen branch and phosphorylating it, thereby producing glucose 1-phosphate
