Isomers + carbs Flashcards
What is an isomer?
Isomers are molecules with the same chemical formulae but different atom arrangements.
Strucural isomers
Structural isomers have the same molecular formula, but the atoms are arranged in a different order
Examples of structural isomers of C6H12O6 are glucose and fructose
Stereoisomers + 2 different types
Stereoisomers have the same arrangement of atoms, but their orientation in 3D space differs.
Geometric: Rigid area, different special arrangements of the atoms
Optical: Non super-imposable (stackable), meer images of each other. When placed together, they do not stack properly
Trans + Cis isomers
trans: opposite sides flipped
Cis: same sides
Biological important macromolecules: Carbohydrates
Roles: Energy, Structure, ID (markers), communication
Monosaccarides
Monosaccharides → most basic building blocks(monomers) of carbohydrates
Glucose (blood sugar): used by cells for energy
Fructose – in fruits, sweeter then glucose
Galactose – found in milk
Two forms of Glucose – alpha and beta
carbon 1 has hydroxyl down→ alpha
upwards → beta
when these sugars build molecules, they will become different polymers
Disaccharides
Disaccharides
composed of two monosaccharides
covalent bond is called glycosidic linkage, forms between specific hydroxyl groups
Galactose and glucose form lactose
Forming Disaccharides by Condensation
(Dehydration) Synthesis
glycosidic link
two hydroxyls from 2 diff monosaccharides bond together, release water to have O make the bond.
Polysaccharide
Energy storage -> starch (amylose nad amylopectin) from plants, glycogen from animals
Structure: cellulose (plants)
fun fact: we can digest alpha linkages, but we have no enymes to eat beta bonds.
Two forms of starch
Amylose alpha 1-4 glycosidic bond
amylopectin: a 1,4 a1,6 linkages
amylopectin has 2 layers, having more structure for storage
Glycogen
Carbohydrate storage in animals; stored in the liver
α 1-4 glycosidic linkage
stacking allows for better storage
Cellulose
Provides structure to plant cell walls.
Using starch to compare, we can see that every second glucose is upside-down.
to accommodate these bonds
the full monomer flips, not a 180 turn
Cellulose – the most abundant organic compound on earth, but…
Cellulose CANNOT be digested due to its β bonds! Animals lack the enzyme to catalyze the reaction. However, humans have found applications for the strong cellulose fibrils: manufacturing paper, lumber products and cotton.
Chitin
Chitin is a polysaccharide consisting of modified glucose molecules called glucosamine
Found in arthropod exoskeletons and fungal cell walls
direction of glucose hydroxyl
down down up down
direction of galactose hydroxyl
down down up up
maltose
2 glucose
lactose
glucose + galactose
sucrose
fructose and glucose
hydroxyl for fructose
up (OH + ch2oh), up, down
