Ch 12 CarbsBiochem Flashcards
Glucose chemical formula
C6H12O6
Monosaccharides, name 3
simple sugars or monomeric sugar (glucose, fructose, galactose)
Disaccharides, name 3 and their monosac ingredients lol
two monosaccharides joined together.
Maltose (glucose + glucose)
Sucrose (glucose + fructose)
Lactose (glucose + galactose)
Polysaccharides
long chains of 20 or more monosaccharides joined together. Straight chained or branched.
4 functions of carbohydrates
- Energy source (organism synthesizes the carbohydrate or acquires it from food sources.)
- serve as intermediates in metabolic pathways
- Play role in structure (ex. Polymers of glucose make up cellulose, the molecule that forms the basis for cornstalks, and also for chitin, which is the basis for the shells of insects.)
- Structural role in DNA and RNA
What is the chemical formula for ribose? Does it follow the general carbohydrate formula? What kind of ring does it form?
C5 H10 O5
yes. (CH(2)O)
Furanose (5 membered)
What are the two functional groups a monosaccharide can have?
Aldehyde HC=O
or Ketone (C=O)
Aldose
a term for monosaccharides with aldehyde group(s)
Ketose
term for monosaccarides with ketone group(s)
Monosaccharides found in nature typically have how many carbons?
three to eight carbons
Carbon-1 in a fischer projection is always what?
in the aldehyde or the closest carbon to the ketone group
What is a stereocenter carbon?
A carbon bonded to 4 different groups. The arrangement can change.
What makes a molecular chiral?
A molecule must contain one or more stereocenters. A carbon is a stereocenter when it has four different groups.
Are R/S handed the same as D/L?
No, R/S relates to movement/priority around a stereocenter carbon.
D/L denotes handedness of WHOLE molecule.
(d or +, l or -) relates to the optical activity of an isomer.
What is the optical activity of an isomer?
How chiral molecules interact with polarized light
Dextrorotary isomers rotate light.
Rotate polarized light in a clockwise direction (to the right).
Levorotary isomers rotate light.
Rotate polarized light in a counterclockwise direction (to the left)
What is the penultimate carbon? What is its significance?
The carbon atom that determines if a sugar is D or L. It is the chiral carbon furthest from the aldehyde or ketone functional group.
How do you determine if a sugar is D or L?
If the hydroxyl (OH) group is to the right (FP), on pointed down(HP), it is a D sugar.
Opposite is L
What is the name of the bond connecting two monosaccharides? How is it formed?
Glycosidic Bond. Condensation / Dehydration reaction between OH groups of two monosaccharides.
Joined by an acetal or ketal linkage
As humans, what kind of carbohydrates do we use?
Right-handed enantiomers (isomers). OH group of the penultimate carbon to the right.
As humans, what kind of amino acids do we use?
Left-handed enantiomers. Amine group to the left of stereocarbon.
What is an enantiomer?
Different compounds that are mirror images of each other, with identical formulas and identical atomic connectivity.
[A kind of isomer (same chemical formula, different structure), specifically, a stereoisomer (relates to optical rotation), that is a mirror image, not identical, not superimposable]
What are the four critical biomolecules of life?
Carbohydrates, Proteins, Lipids, Nucleic Acids
Most common ketohexose?
Fructose
What is the anomeric carbon?
The aldehyde or ketone carbon now becomes a stereocenter carbon. It’s new OH group can point up or down.
If the OH group is pointing up at the anomeric carbon, is the molecule beta or alpha?
Beta. Beta is beautiful and she points up.
If the OH group is pointing down at the anomeric carbon, is the molecule beta or alpha?
Alpha. Alpha is an ass, so he is down.
When forming a cyclic sugar configuration, which group is being oxidized, and which group is being reduced?
An OH group is being oxidized. It is kicking out its hydrogen atom and gaining a bond to a now lonely oxygen.
The carbonyl group accepts this electron and loses one of its bonds (previously a double bond) with oxygen and bonds with hydrogen.
What are three polysaccharides
Cellulose, Starch, Glycogen
Why can’t we digest cellulose?
Cellulose is a long-chain of beta-d-glucose, and we do not have the enzymes required to break that linkage.
What are starch and glucose made from? Why can we digest it?
Starch and glucose are made from alpha-d-glucose chains. We contain the right enzymes (amylase and amylopectin) to break these structures down.
