Biochemistry Exam 2 Study Guide
Chapter 7: Carbohydrates
I. Carbohydrates
A. Most abundant organic molecule in nature
a) 3 major classes:
Monosaccharides – simple sugar – polyhydroxy aldehyde or ketone; represent individual sugar
Oligosaccharides – consist of short chains of monosaccharide units joined together by covalent bonds; 2-10 strings of sugar
Polysaccharides – long chains having hundreds or thousands of monosaccharide units
b) Functions:
Provide energy thru oxidation – glucose oxidized for energy
Supply carbon for synthesis of cell components
Energy storage to form a part of structural elements of some cells and tissues; glucose stored as glycogen
c) Classification
General formula (CH2O)n where n is any integer from 3-7
Monosaccharides are either aldehydes or ketones
Aldoses – monosaccharides that contain aldehydes
Ketoses – monosaccharides that contain ketones
d) Also classified by number of carbons:
3 carbons – trioses, 4 carbons – tetroses, 5 C’s – pentoses, 6 C’s – hexoses, 7 C’s – heptoses
Each of these exist in 2 series: aldotrioses and ketotrioses, aldotetroses and ketotetroses, aldopentoses and ketopentoses, aldohexoses and ketohexoses, aldoheptoses and ketoheptoses
B. Stereochemistry
a) Stereoisomers: all atoms are bonded together with exactly the same bonding pattern but differ only in the arrangements of their atoms in space
b) Enantiomers:
Non-superimposable mirror-image pairs of stereoisomers (left and right hand)
Observed only when a carbon atom has 4 diff groups attached to it (e.g. CHXYZ also called chiral molecules)
One of the enantiomeric pair is a member of the D-family and other is L-family
c) Properties of Enantiomers
Have identical physical and chemical properties
They rotate the plane of the plane-polarized light by equal degrees but in opposite direction
Those that rotate plane-polarized light clockwise are called dextrorotatory and are designated and plus (+).
Those that rotate plane-polarized light
I. Carbohydrates
A. Most abundant organic molecule in nature
a) 3 major classes:
Monosaccharides – simple sugar – polyhydroxy aldehyde or ketone; represent individual sugar
Oligosaccharides – consist of short chains of monosaccharide units joined together by covalent bonds; 2-10 strings of sugar
Polysaccharides – long chains having hundreds or thousands of monosaccharide units
b) Functions:
Provide energy thru oxidation – glucose oxidized for energy
Supply carbon for synthesis of cell components
Energy storage to form a part of structural elements of some cells and tissues; glucose stored as glycogen
c) Classification
General formula (CH2O)n where n is any integer from 3-7
Monosaccharides are either aldehydes or ketones
Aldoses – monosaccharides that contain aldehydes
Ketoses – monosaccharides that contain ketones
d) Also classified by number of carbons:
3 carbons – trioses, 4 carbons – tetroses, 5 C’s – pentoses, 6 C’s – hexoses, 7 C’s – heptoses
Each of these exist in 2 series: aldotrioses and ketotrioses, aldotetroses and ketotetroses, aldopentoses and ketopentoses, aldohexoses and ketohexoses, aldoheptoses and ketoheptoses
B. Stereochemistry
a) Stereoisomers: all atoms are bonded together with exactly the same bonding pattern but differ only in the arrangements of their atoms in space
b) Enantiomers:
Non-superimposable mirror-image pairs of stereoisomers (left and right hand)
Observed only when a carbon atom has 4 diff groups attached to it (e.g. CHXYZ also called chiral molecules)
One of the enantiomeric pair is a member of the D-family and other is L-family
c) Properties of Enantiomers
Have identical physical and chemical properties
They rotate the plane of the plane-polarized light by equal degrees but in opposite direction
Those that rotate plane-polarized light clockwise are called dextrorotatory and are designated and plus (+).
Those that rotate plane-polarized light