BIOCHEM WEEK 3 Flashcards
• most abundant class of bioorganic molecules on planet Earth
Carbohydrates
CHO in plants
– structural elements
Cellulose
CHO in plants
energy reserve
Starch
provides energy.
Oxidation
Storage
glycogen
– for synthesis of other biologic substances
C atom source
DNA and RNA structural component
ribose & deoxyribose
Cell membrane component
glycolipids
Cell-cell and Cell-Molecule recognition processes
glycoprotein
largest source of dietary calories for most of the world’s population
Carbohydrates
• A carbohydrate that contains a single polyhydroxy aldehyde or polyhydroxy ketone unit or
• Cannot be broken down into simpler units by hydrolysis
• Usually contains 3-7 carbon atoms
• Water-soluble
• Crystalline solids
MONOsaccharide
• 2 monosaccharides covalently bonded to each other
• Produces monosaccharides upon hydrolysis
• Water-soluble
• Crystalline
DIsaccharide
• 3-10 monosaccharides covalently bonded to each other
• Produces monosaccharides upon hydrolysis
• Mostly not digested by human enzymes
Examples
• Raffinose • Stachyose
OLIGOsaccharide
• MANY monosaccharides covalently bonded to each other
• Produces monosaccharides upon hydrolysis
Examples
• Glycogen • Cellulose • Starch
POLYsaccharide
• name ends in –ose
§ except: Glyceraldehyde &
Dihydroxyacetone
• can be classified based on
§ number of carbons v Triose
v Tetrose v Pentose v Hexose
§ functional group v Aldose
v Ketose
Monosaccharides
have the same molecular and structural formulas but differ in orientation of atoms in space
The left and right-handed forms of a chiral molecule
isomers
nonsuperimposable mirror images
e.g. left- and right-handed forms of a molecule
Enantiomers
not mirror images of each others
Diastereomers
Type of isomerism founds in carbohydrates
§ Superimposable
§ Non-superimposable
– C atom bonded to 4 different groups
Chiral Center
(t or f)
• All proteins, most fats, and all common carbohydrates are chiral
true
are almost always right-handed
Monosaccharides
are always left-handed
Amino acids
2D notation for showing the spatial arrangement of groups about chiral centers in molecules
• Chiral center is represented as the intersection of vertical and horizontal lines
Fischer Projection
(t or f)
§ D stands for Dextro – right
§ L stands for Levo - left
true
Isomers in which the atoms have different connectivity
Constitutional Isomers
isomers with atoms of the same connectivity that differ only in the orientation of the atoms in space
Stereoisomers