On the basis of numbers of saccharides in hydrolysis, Carbohydrates are classified as Monosaccharides, OligO
saccharides and Polysaccharides.

1. They are simplest sugars which can not be further hydrolysed.
2. In their generalised formula xis mostly equal toy i.e. number of Carbon and Oxygen atoms same.
3. First step of oxidation- Phosphorylation
4. All monosaccharides occur in d and I form, except the Dihydroxy acetone.
5. The structure of saccharides is either ring or straight chain.
6. A six membered ring is ]mown as pyranose and five membered ring is furanose.
Pyranose and furanose names were given by "Haworth."
7. Anomer- In aqueous solution, Clucose occurs in cyclic structure. In anomers, position of `-H` and `-OH` groups are changed on cl carbon atom.

Epimer : Isomer formed as a resul1 of interchange of the `-OH` and `-H` groups on carbon atom `2, 3` and `4` of glucose, are known as epimer.
Epimer of Glucose :
Mannose (Difference on `C_2` carbon)
Galactose (Difference on `C_ 4` carbon)

# Chemically all carbohydrates are polyhydroxy aldehyde or ketones.

1. Trioses : Number of carbons = 3 (Simplest monosaccharide)
# common formulae `= C_(3) H_(6)O_(3)`

e.g. DHAP , PGAL

2. Tetroses: Number of carbons= 4
# Common Formulae `=C_(4)H_(8)O_(4)`

e.g. Erythrose, Erythrulose

3 . Pentose : Number of carbons = 5

# Common Formulae `= C_(5)H_(10)O_(5)`

e.g. Xylose
Xylulose
Deoxyribose
Arabinose
Ribose
Ribulose

# Present in RNA, ATP, FAD, FMN, NAD # Present in DNA
# Molecular Formulae `= C_(5)H_(10)O_(5)` #Molecular formulae `= C_(5)H_(10)o_( 4)` (Exception)

4. Hexoses : Number of carbons `= 6`
Common Formulae `= C_(6)H(12)O_(6)`

e.g. Rhamnose
Mannose
Galactose
Glucose
Fructose

Glucose : More abundant in grapes so also known as grape sugar.
# More abundant in blood so known as blood sugar.
# Main respiratory substance.
# It rotates PPL in right direction so it is dextrorotatory and also known as dextrose.

Fructose:

# Sweetest carbohydrate
# More abundant in honey and sweet fruits so also known as fruit sugar.
# Rotates PPL in left direction so it is laevorotatory and also known as 'Laevulose'.
# Thaumatine is sweetest chemical substance which is obtained from Thaumatococcus danielli bacteria.
# Aspartame/Aspartin is most commonly used artificial sweetener. It is non carcinogenic.


Galactose:


# Most abundant in brain and nervous tissue so called as 'brain sugar'.
# It never occurs in free form. 11 always occurs as a component of some compounds.
e.g. Hemicellulose, Lactose, Pectin, Clycolipid

Mannose:
# It also never occurs in free form.
# It is present as a component of some compounds.
e.g. Albumen- Egg
Hemicellulose - Wood

Rhamnose:

# One oxygen atom is deficient in it's structure so molecular formulae is `C_(6)H_(12)O_( 5)` (Exception)
# Present in phloem.

5. Heptoses : Number of carbons `= 7` (Largest monosaccharide)
Common formulae `= C_(7)H_(14)O_(7)`
e.g. Sedoheptulose

# Monosaccharides with free aldehyde group are termed as Aldoses (PGAL, Erythrose, H.ibose, Arabinose, Deoxyribose, Clucose, Galactose, Mannose).

# While monosaccharides with free ketone group are called ketoses (DHAP, Erythrulose, Ribulose, xylulose, Fructose, Sedoheptulose).
All monosaccharides are "reducing sugars" as their free aldehyde or ketone groups are capable of reducing `Cu^(++)` to `Cu^(+)`.
This property is the basis of Benedict's test or fehling's test used to detect the presence of glucose in urine.