CARBOHYDRATES

3 different categories 1. monosaccharides: simple sugars

a)  trioses ex. G3P (glyceraldehyde 3 phosphate)

CARBOHYDRATES ¢  all contain (C H O) ¢  high energy compounds due to high

potential energy in C-H

empirical formula

2- 8 C atoms

(3C) C3H6O3 1

2

3

2 n

b)  pentoses

ex i. ribose (in RNA) ii. deoxyribose (in DNA)

CARBOHYDRATES (5C)

C5H10O5

C5H10O4

c)  hexoses

ex. glucose •  exists in chain (linear) or ring structures

CARBOHYDRATES

(6C)

(crystallized)

C6H12O6

(dissolved)

1

2

3

4 5

6

•  internal rearrangement in solution as C1 joins with C5

1

2 3

4 5

6 + H2O

- H2O

• forms a(n) ________ linkage ether D glucose

isomers: •  same molecular formula, but different structure ex. fructose & galactose are isomers of glucose

•  all have same formula

CARBOHYDRATES

C6H12O6

α  - glucose β - galactose fructose

stereoisomers

+

2.  disaccharides •  synthesized by condensation rxn’s

CARBOHYDRATES

β  

glucose

glucose + glucose maltose

+ α - H2O

1 2 3

4 5

6

1 2 3

4 5

6

ether linkage

+

α (1-4)

ether linkage β (1-4)

1

2 3

4 5

6

α

H2O

CARBOHYDRATES

sucrose + glucose fructose + H2O

lactose + glucose galactose + H2O

main transport sugar in plants

disaccharride found in milk

3.  polysaccharides •  polymers of 1000’s of monosaccharides ex. a) starch

•  short term energy storage in plants •  long chains of glucose [α (1-4) ether linkages] •  short branches

2.  disaccharides (continued)

twisted into a helix

CARBOHYDRATES 3.  polysaccharides(continued) ex. b) glycogen

•  short term energy storage in animals

•  like starch [α (1-4) ether linkages] but highly branched

•  side chains [α (1-6) ether linkages]

c) cellulose •  makes up cell walls in plants •  no side branches •  forms long rigid molecules,

linked by β (1-4) ether linkages •  indigestible to humans (fibre)

CARBOHYDRATES 3.  polysaccharides (continued) ex. d) chitin

•  modified cellulose with amide groups •  very tough resistant molecule •  forms cell wall of fungi & exoskeleton on insects

starch

glycogen

cellulose

HOMEWORK Enzyme & Energy Quiz on Monday