carbohydrates Flashcards
what are the range of different uses for carbohydrates?
1) ) Source of energy
- input for energy generation pathways e.g. glycolysis
- source material for making other biomolecules e.g. They can be converted into amino acid via transamination (amino acid synthesis) or the generation of nucleic acids (RNA and DNA).
2) Structural
- DNA (Ribose; Monosaccharide)
- Plant Wall (Cellulose; Polysaccharide)
- Drugs and Hormones (receptors that recognise these hormones also have carbohydrates attached to them.
( e.g. Adenosine; Ribose)
carbohydrate
what molecules do they contain?
what is the molar ration?
Biological molecules which contain carbon, oxygen and hydrogen in very specific ratio.
Molar ration C1H2O1= C1(H2O)1 (for every one molecule of carbon there is one water molecule)
what are the simplest form of carbohydrates and what are the common types including molecular DRAWINGS and Formulas ?
simplest form = Monosaccharides
-glucose
- galactose
- fructose
All have the same molecular formula (C6H12O6)
Triose, Tetrose, pentose, hexose
Triose
Carbons: 3
Example : Pyruvate, glyceraldehyde, dihydroxyacetone.
Importance: Intermediates glycolysis, precursor of glycerol (for lipid synthesis)
Tetrose
carbons : 4
Example : D- Erythrose
Importance: Intermediates of carbohydrate metabolism.
Pentose
Carbons : 5
Example: D- ribose
Importce: Structural element of nucleic acid, RNA, Co-enzymes.
Hexose
Carbons : 6
Example : D- Glucose
Importance: Mian sugar of the body
Example : D-Fructose
Importance: Converted to glucose and utilised by the body
Example: D-Galactose
Importance: Synthesised in mammary gland to make the lactose of milk.
Example : D-Mannose
Importance: Constituent of glycoprotein, glycolipids.
what is polymerisation?
(condensation)
adding carbohydrate monomers to build something big.
what is formed when one or more type of monosaccharides are combined together?
2 Monosaccharides = Disaccharide
3-20 Monosaccharides = Oligosaccharides
21-1000’s Monosaccharides= Polysaccharides
what happens when two monosaccharides join together?
No matter what size, for every two monosaccharides that combine it results in the overall loss of one water molecule = Condensation
Formation of disaccharides.
Glucose + Glucose = Maltose
Galactose + Glucose = Lactose
Fructose + Glucose= Sucrose
Formation of Trisaccharides
Glucose + Fructose + Galactose = Raffinose
Formation of Tetrasaccharide
2X Galactose + Glucose + Fructose = Stachyose
Formation of Pentasaccharides
3X Galactose + Glucose + Fructose = Verbascose
Molecular formulas of Maltose, Lactose and Sucrose.
BOOK
What is carbon 1 known as ?
Anomeric carbon- when forming bonds with sugars this is the atom which dictates how two sugars interact.
Types of ways to represent the same molecule.
- Fischer (like display formula/lines)
- Haworth ( the “normal” way)
- chair/boat (3D)
- stereochemical (2D)
what is the differnece between a-glucose and b- glucose.
a- glucose
The OH on the anomeric carbon is Trans (opposite side) compared with the OH group in carbon 6.
B- glucose
The OH group on the anomeric carbon is Cis (same side) compared with the OH group in carbon 6.
what is chirality?
Chirality is a property of asymmetry in molecules, where a chiral molecule cannot be superimposed on its mirror image-
This is similar to how your left and right hands are mirror images of each other but are not identical.
D-Glucose and L-Glucose are mirror images of each other and are enantiomers.
what are enantiomers?
Enantiomers are two chiral molecules which have the same chemical formula but the atoms are arranged as a mirror image- no matter how we rotate or translate them individually they cannot be superimposed (they cannot be made to match exactly).
where is chirality (“handedness”) of a molecule important.
for enzyme/protein recognition in metabolism- one enantiomer fits perfectly in the enzymes active site/pocket, while the other enantiomer (mirror image) will not be a perfect fit= no biological response.
which one of these sugar are naturally occurring?
D-sugars = naturally occurring
L- sugars = do not occur naturally but can be made synthetical
D&L used for what?
used to define chirality of a sugar. Most of the sugars in nature are in the D formation. Conversely amino acids are in the L conformation.
D=Dexter= right
L=Laevis= left
What does Emil Fischer suggest?
Emil Fischer
- Atoms C and D (solid wedge) = projecting out of the page= horizontal line
-Atoms A and B (dashed wedge)= projected into the page= vertical line.
IMAGE IN BOOK
What does the penultimate carbon mean?
refers to the second-to-last carbon atom in a chain of carbon atoms.
LEARN HOW TO IDENTIFY !
How to know if a molecule is D or L?
The two molecules are identical apart from the position of the OH group on the penultimate carbon (*).
If the OH group is on the right hand side of the penultimate carbon, its a D sugar.
If the OH group is on the Left hand side of the penultimate carbon, it a L sugar.
Therefore, Fischer projections= sugar Enantiomers.
what does diastereomers mean?
(two) molecules which are not mirror images of each other and each molecules has multiple chiral centres (*).
DIAGRAM IN BOOK!
