CARBOHYDRATES PART 1
are one of the three major classes of biological molecules.
are also the most abundant biological molecules.
Carbohydrates
Some of the important Functions of Carbohydrates
1) Energy
2. Provides dietary Fiber
3. Structural
4. Intercellular Communication
glucose fuels the work of most of the body’s cells
preferred fuel of NERVOUS TISSUE (the brain, nerves) and RED BLOOD CELLS (RBC)
excess glucose is stored as GLYCOGEN in liver and muscle tissue
Energy
Found in plants
increase fecal weight and soften stool to ease passage
reduces risk of hemorrhoids, diverticulitis, appendicitis and colon cancer
beneficial for weight control by contributing to satiety & delay gastric emptying
soluble fibers lower blood cholesterol to help reduce risk of cardiovascular disease
2. Provides dietary Fiber
Carbohydrates Contain the Elements:
Carbon
Hydrogen
Oxygen
The formula for a carbohydrate is___
(CH2O)n
- it has a 3 carbons.. example
Triose---Glyceraldehydes
- it has a 4 carbons.. example
Tetrose-------Threose, Erythrose
- it has a 5 carbons.. example
Pentose------Ribose, Xylose, Xylulose
- it has a 6 carbons.. example
Hexose-----Glucose, Galactose, Fructose, Mannose
All carbohydrates can be classified as:
1. Monosaccharides
2. Disaccharides
3. Oligosaccharide
4. Polysaccharides
- one unit of carbohydrate
1. Monosaccharides
example of Monosaccharides
a) Glucose
b) Fructose
c) Galactose
carbohydrate form used by the body; referred to as “blood sugar”
basic sub-unit of other larger carbohydrate molecules
found in fruits, vegetables, honey
a) Glucose
sweetest of the sugars
occurs naturally in fruits & honey, “fruit sugar”
b) Fructose
It combines with glucose to form lactose, “milk sugar”
c) Galactose
- Two units of carbohydrates joined by glycosidic bond.
2. Disaccharides
- example of Disaccharides
a) Sucrose
b) Lactose
c) Maltose
= fructose + glucose (also known as “table sugar” )
a) Sucrose
= galactose + glucose (also known as “milk sugar”)
b) Lactose
= glucose + glucose (also known as “malt sugar”, maltose is in beer)
c) Maltose
- Anywhere from three to ten monosaccharide units joined by glycosidic bonds.
found in legumes and human milk
3. Oligosaccharide
example of Oligosaccharide
a. raffinose
b. stachyose
__________ are much larger, containing hundreds of monosaccharide units joined by glycosidic bonds.
4. Polysaccharides
example of Polysaccharides
a. Starch
b. Glycogen
c. Cellulose
plant storage form of carbohydrate
long branched or unbranched chains of glucose
a. Starch
animal storage form of carbohydrate
highly branched chains of glucose units
found in LIVER and MUSCLE
Humans store ~ 100g in liver; ~ 400g in muscle
b. Glycogen
consisting of a linear chain of several hundred to many thousands of β(1→4) linked glucose units commonly found in plant’s cell wall.
This β-1,4 bonds cannot be broken by human enzymes; hence it is a non-digestible carbohydrates found in all types of plant foods
Often referred to as “Dietary fiber”
c. Cellulose
Carbohydrates also can combine with lipids to form _____
With proteins to form ____.
1. glycolipids
2. glycoproteins.
Carbohydrates are chemically characterized as:
1. Aldose
2. Ketose
Sugars that contain an aldehyde group.
Examples of aldoses are Glucose, Galactose, and Mannose. They are also known as aldohexose.
1. Aldose
Sugars that contain a keto group.
Examples of ketos is fructose. It is also known as ketohexose.
2. Ketose
_____ are molecules that have the same molecular formula, but have a different arrangement of the atoms in space.
Same chemical formula C6 H12 O6
ISOMERS
Examples of isomers:
Glucose
Fructose
Galactose
Mannose
______ are sugars that differ in configuration at ONLY 1 POSITION. (of course, they are also isomers)
EPIMERS
Examples of epimers :
D-glucose & D-galactose (epimeric at C4)
D-glucose & D-mannose (epimeric at C2)