Tuesday, June 28, 2011

biochemistry- Carbohydrates

Assalamualaikum :)

Today we'll learn about carbohydrates, a essential polymer that needs by our body as well as the other organisms too. Ok, let's start! (ecehh,,poyo kot..haha)

First thing first, let's do a little briefing about carbohydrates. Carbohydrates is consists of element C,H and O, which include:

  1. Monosaccharides
  2. Disaccharides/oligosaccharides
  3. Polysaccharides
just proceed to the components of carbohydrates...


  • the simple sugars of (CHnO)n, where n=3,4,5,6,7. (more than 7 is not a monosaccharide)
  • the simplest form of sugar, cannot be hydrolysed anymore.
  • Divided into two types, aldose and ketose.
  • Each monosaccharide MUST have one hydroxyl (-OH) and one carbonyl (=O) group
  • Structure of monosaccharide can be represented in THREE ways,
  1. straight chain (Fischer Projection)
  2. cyclic/ring form (Haworth Projection)
  3. chair/boat form.

Fischer projection

Haworth Projection

Chair Form

*Glucose can form over 16 isomers. Yet, the most important types (that you must remember) are:
  1. D and L isomerism
  2. Epimers
  3. Aldose-ketose isomerism
  4. Pyranose and furanose ring strutures
  5. Alpha and beta anomers

D and L isomerism

The position of H and OH in carbon number 5 (C5) determines whether the sugar belongs to D or the L series.
If -OH on the right, the sugar is the D isomer
If -OH on the left, the sugar is the L isomer. *Note: L=LEFT



Isomers that differs due to the variation of H and OH position on C2, C3 and C4 of the glucose:
At C2 and C4, if -OH on the right, the sugar is glucose
At C2, If -OH on the left, the sugar is mannose
At C4, if -OH on the left, the sugar is galactose 
*the carbon where the rotation occurs is called the anomeric carbon 

Aldose-Ketose Isomerism

Depends on the position of the carbonyl group. If, the carbonyl in C1, the sugar is aldose. If the carbonyl group is in C2, it is a ketose. In this chapter, we use glucose as aldehyde while fructose as ketones.

Pyranose and Furanose Ring

Those with 5 membered ring structure (furan) are called furanoses, while one with 6 membered rings (pyran) are called pyranose.
(in Haworth projection -ring form)


p/s: how the ring can be formed. The H on the fifth carbon (C5) combine with O at the first carbon. The remaining O (kan asalnya OH) become the connector.

Ok, masuk pulak pada jenis2 monosaccharide mengikut bilangan CARBON ATOM
Yang kitorang belajar ade triose(3), pentose (5), hexose (6).


  • Molcular formula : C5H10O5
  • Example: Ribose and Deoxyribose
  • D-Ribose found in coenzymes, ATP and RNA



*beza deoxyribose dengan ribose ialah komponen pada C ke 2 dalam ring form. Ribose: OH, Deoxyribose:H


Molcular formula : C6H10O6
Example (the most common): glucose, galactose, fructose------>strukur2 dy dah dibezakan masa kat atas tadi
*All the three hexoses share the same molecular formula but ARRANGEMENT OF THE ATOMS are DIFFERENT (structural isomers)


bersambung kemudian...bnyaaaaak lagi ni.>!! yada2~

Ingatlah hadith nabi: Rasulullah s.a.w bersabda, maksudnya:

"Siapa yang keluar untuk menuntut ilmu maka ia berjuang fisabilillah hingga ia kembali".

Sekian :)


husna assaedah said...

ahhh..tidakkk!!! ak blom study bio chapter 3~~~~~

mood: separuh nyawa!!

kiwi_baek! said...

aku baru blaja ni!!

bANanA (",) said...

laa ciput je ke..ingtkn pnjg lg
next tym mengajar lg ye doc ~ haha

umi said...


haru_maki said...

ape umi...kate minat chem~