MCP Flashcards
Carbohydrates
- chemical formulas = (CH2O)n, where n >/= 3
- basic carbohydrate unit = monosaccharide
- monosaccharides may be covalently linked together to form oligosaccharides and polysaccharides
Monosaccharides
-classified by the number of carbons such as pentose for 5 carbons and hexoses for 6 carbons
what are the smallest monosaccharides? and how many carbons do they have?
Trioses, 3 carbons
What are monosaccharides classifications based on? What are the two types?
- based on chemical nature of the carbonyl group
- aldose if carbonyl is an aldehyde
- ketose if carbonyl is a ketone
What are the most common aldoses?
- glyceraldehyde (triose)
- ribose (pentose)
- glucose, mannose and galactose (hexoses)
what are the most common ketoses?
- dihydoxyacetone (triose)
- ribulose (pentose)
- fructose (hexoses)
What form are monosaccharides most often found in ?
CYCLIC
What is the anomeric carbon?
anomeric carbon is the carbon -which was the former carbonyl carbon which when forming cyclic rings reacts with one of the -OH groups to form a hemiacetal or hemiketal
- C1 in aldoses
- C2 in Ketoses
What is a reducing sugar?
A reducing sugar is an anomeric carbon that’s oxygen does not have anything else bound to it -with anomeric carbon considered the reducing end
What type of bond links monosaccharides ?
glycosidic bonds
Define Disaccharide
two sugar residues covalently linked via a glycosidic bond
Define Oligosaccharide
short typically 2-15 sugars linear or branched chain of sugars covalently bound to one another via glycosidic linkages
Define polysaccharide
long linear or branched polymer of sugar covalently bound or linked to one another via glycosidic linkages (may consist of hundreds of sugars)
Where are carbohydrates principally digested?
the mouth and small intestines
amylose
found in starch linear polysaccharide consisting of 100s to 1,000,000 of glucose residues in alpha-1,4 linkage
amylopectin
found in starch- branched polysaccharide consisting of 100s to 1,000,000s of glucose residues in alpha -1,4 linkage with alpha-1,6 branches
lactose
dissacharide consisting of galactose and glucose in beta-1,4 linkage; found in dairy and milk products
sucrose
(table sugar) -disaccharide consisting of glucose and fructose in alpha-1,2 linkage; this is a non-reducing sugar because of the -OH’s of the two anomeric carbons are not free
glycogen
branched polysaccharide consisting of hundreds to millions of glucose residues in alpha-1,4 linkage with alpha-1,6 branches; same basic structure as amylopectin, but more highly branched; storage form of glucose found in most cells greatest in liver and skeletal muscle
Cellulose
(major component of dietary fiber) -linear polysaccharide consisting of hundreds to millions of glucose residues in Beta-1,4 linkage; cannot be digested by humans because we don’t have the enzyme that will cleave the glucose to glucose beta-1,4 linkage
Define glycosidases
a large group of enzymes that cleave a wide array of glycosidic linkages
endogylcosidases
cleave internal glycosidic bonds in sugar plymers
exoglycosidases
cleave terminal glycosidic bonds in sugar polymers
disaccahridases
cleave glycosidic bonds in disaccharides
What factors determine the specific glycosidase used?
- structure of the glycosidic linkage
- specific sugars on either side of the linkage
- position of the glycosidic linkage within the polymer (i.e. terminal vs. internal)
Alpha amylase
endoglucosidase that hydrolyzes random internal alpha-1,4 bonds between glucose residues in starch (both amylopectin and amylose)
Salivary alpha amylase
produced in the salivary glands in the mouth-cleaves starch polymers into smaller polysaccharides. It is inactivated in the stomach (bc of acidic pH)
Pancreatic alpha amylase
produced by the pancreas and secreted into the duodenum- it continues hydrolyzing the starch digestion products to produce maltose, maltotriose and longer linear oligosaccharides, alpha dextrins and isomaltose
Dextrin
oligosaccharide which has at least one alpha-1,6 linkage by definition
Glucoamylase
an exoglucosidase that cleaves a terminal alpha-1,4 bond between glucose beginning in the non-reducing end; substrates include maltose, maltotriose, alpha dextrin, amylose, and amylopectin; produces glucose and isomaltose
maltase
cleaves the alpha-1,4 bond in maltose and maltotirose to produce glucose and maltose
isomaltase
cleaves the alpha-1,6 bond in the isomaltose and alpha dextrins to produce glucose and glucose polymers
sucrase
cleaves the alpha-1,2 bond in sucrose to produce glucose and fructose
lactase
cleaves the beta-1,4 bond in lactose to produce galactose and glucose
Lactose Intolerance
found in 75% of world’s population- because evolutionary new trait to be able to digest milk beyond infancy and childhood - must cause symptoms to be considered lactose intolerant
Tay Sachs Disease
defect in enzyme = B- hexosaminidase
accumulated substrate = gangliosides G M2
Gaucher disease
enzyme = Beta glucossidases
accumulation of glucocerebrosides
Metachromatic Leukodystrophy
enzyme = arylsulfatase
accumulation of sulfatides
Krabbe disease (Globoid cell leukodystrophy)
enzyme= Beta galactosidases
accumulation of galactocerebrosides
Gangliosidosis
enzyme = beta galactosidases
accumulation of gangliosides
Sandhoff disease
enzyme beta hexosaminidase
accumulation of globosides
Farby disease
enzyme - alpha galactosidase
accumulation of globosides
X LINKED
Nieman-Pick Disease (A + B)
Enzyme= sphingomyelinase
accumulation of sphingomyelin
Farber disease
enzyme = ceraminidase
accumulation of ceramide
