Chapter 7 Flashcards
What are the physiological roles of carbohydrates?
Sources of energy Energy storage Structural roles Cellular interaction Cellular identification Information transfer (DNA RNA) Signaling
What is the empirical formula of carbohydrates?
(CH2O)n
Where n > or equal to 3
What are the two major classes of carbohydrates?
Aldoses- have aldehyde groups CHO (double bonded O)
Ketoses- have ketose groups
A C attached to two CH2OH’s and a double bonded oxygen
Memorize the 6 common monosaccharide sugars
Aight
What are epimers?
Sugars that differ at a single chiral center (H and OH are switched around)
Ex: C3 epimer of _______
H and OH at third carbon are switched
What happens to carbohydrates of 5 carbons or longer in solution?
They tend to be cyclized
Wrap in a circle
What is the formation of the cyclical structure of carbohydrates a result of?
A reaction of alcohol with either:
- An aldehyde (aldoses) to form hemiacetal
- A ketone (ketoses) to form hemiketal
Look at diagrams on slide 8
What are the two forms of cyclized carbohydrates?
Six-membered sugar ring is a pyranose
glucopyranose
Five-membered sugar ring is a furanose
ribofuranose
What bonds form to create cyclized structures of carbohydrates?
The free hydroxyl of C-5 and the aldehyde group of C-1
What two stereoisomers are produced by C-1 in cyclizing?
α and β
Alpha and beta stereoisomers are produced
α is where the H is above the OH on C-1 on the very right of the molecule
β is where the OH is above the H on C-1 on the very right of the molecule
Alpha and beta are anomers of eachother
On slide 10
What is mutarotation?
Where the α and β configurations interconvert through a linear intermediate
Change in configuration
Diagram on slide 12
Is a carbohydrate is swapped from D to L how does that affect the α and β of the cyclized form?
It will change the α to β or vice versa
Ex: β-L-Fucose has H over OH on C-1
Do practice naming on slide 15
How do plants use glucosinate and myrosinase as defence?
The myrosinase acts on glucosinolate to produce glucose and isothiocyanate which has a sharp and bitter taste
This bitter taste functions to discourage herbivores from eating plant
Slide 16
How do reducing agents work with monosaccharides?
Monosaccharides can be oxidized by mild oxidizing agents like Iron and copper
When this happens the carbonyl group (CHO) is oxidized to a carboxyl group (COOH)
Allows for quantifications of sugars present in blood or urine
What is a gylcosidic bond?
What are the two types?
Primary structural linkage in all polymers of monosaccharides
O-glycosidic bonds occur through oxygen
N-glycosidic bonds occur through nitrogen