6. LETS LEARN SOME GREEK!!!!
The name glucose comes from the Greek word
glykys (γλυκύς), meaning "sweet", plus the suffix
"-ose" which denotes a sugar
4 chiral centers give 24 = the 16 stereoisomer s
of hexose sugars. Chirality, or "handedness",
Greek, (χειρ), kheir: "hand” chiral carbons are
enantiomers
Alpha α and Beta β are letters in the Greek
alphabet
7. Carbohydrates
• Carbohydrates, or saccharides (saccharo is Greek for ―sugar)
are polyhydroxy aldehydes or ketones, or substances that yield such
compounds on hydrolysis.
• Carbohydrates include not only sugar, but also the starches that
we find in foods, such as bread, pasta, and rice.
• The term ―carbohydrate comes from the observation that when
you heat sugars, you get carbon and water (hence, hydrate of
carbon).
8. Carbohydrates and Biochemistry
•Carbohydrates are compounds of tremendous
biological importance:
–they provide energy through oxidation
–they supply carbon for the synthesis of cell
components
–they serve as a form of stored chemical energy
–they form part of the structures of some cells and
tissues
•Carbohydrates, along with lipids, proteins, nucleic
acids, and other compounds are known as
biomolecules because they are closely associated with
living organisms.
21. 2. MONOSACCHARIDES
• Once a monosaccharide has been named as an aldose or a ketose, and the number of
carbons has been designated, there are still several different isomeric forms for each.
•
Each specific monosaccharide has a unique name.
•
A prefix (D- or L-) is added to designate which of two possible isomeric forms is being referred
to.
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33. Additional info:
monomer: a molecule that may react chemically
to another molecule to form polymer; the
simplest unit; repeating unit of polymer
polymer: a compound made up of several
repeating units (monomer)
enzyme: speeds up chemical reaction
34. CLASSIFICATION:
1- Monosaccharides (simple sugars):
They can not be hydrolyzed into simpler units. E.g. glucose,
galactose,ribose
2- Oligosaccharides (oligo = few): contain from two to ten
monosaccharide units joined in glycosidic bonds. e.g.
• disaccharides (2 units) e.g. maltose and sucrose,
• trisaccharides (3 units).....etc.
3-Polysaccharides (poly = many): Also known as glycans. They are
composed of more than ten monosaccharide units e.g. starch,
glycogen, cellulose.....etc.
35. 2- According to the characteristic carbonyl group (aldehyde or ketone group):
- Aldo sugars: aldoses:
Contain aldehyde group e.g. glucose, ribose, erythrose and glyceraldehydes.
- Keto sugars: ketoses:
Contain ketone group e.g. fructose, ribulose and dihydroxy acetone.
36. GLUCOSE FORMS A RING STRUCTURE
Note: functional group is on carbon one
37. TWO TYPES OF RING
STRUCTURES FOR GLUCOSE
OH on carbon one:
BELOW the ring
ABOVE the ring
38. The existence of - and -isomers: leads to greater chemical variety
is of importance in for example in
forming starch and cellulose
39. NOTE DIFFERENCE:
The main difference between glucose and galactose
is that glucose is much sweeter than galactose.
40. 13.4. REACTIONS--ADDITION
• Addition of an alcohol to an aldehyde:
H+
• The product is called a hemiacetal (-OH and –OR attached to the same carbon).
•
Hemiacetals are very reactive.
•
They react with an additional alcohol molecule, losing –OH and adding another –OR.
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42. 13.4. REACTIONS--ADDITION
• Ketones undergo analogous addition reactions with alcohols.
•
The initial product is a reactive hemiketal (two –R groups, one –OH, and one –OR).
•
An additional –OR group is added to the hemiketal to produce a ketal.
hemiketal
ketal
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