Biochem: Carbohydrates Flashcards
What are the functions of sugar
- cell resp
- energy storage
- structural components
- cell surface markers
how does sugar mark cells?
sticks out for membrane, providing identification of type of cell
- all cells have specific carb structure
what is the purpose of cell markers
allows body to detect outside cells
common characteristics of sugar
- ends in ose
- hydrocarbon chain embedded with -OH
- always a carbonyl
what are chiral centres
mirror images
L/D: optical isomers/stereoisomers
- glucose has L & D versions, we naturally make and use D glucose
R/S: ematiomers
what is the diff between α and β glucose?
direction of hydroxyl group
if α: away/down
if β: towards/up
ONLY IMPORTANT IN POLYMERS
explain dehydration synthesis in carbs
enzyme combines two monosaccharides hydroxyl groups to produce a disaccharide
- oxygen bridge is GLYCOSIDIC LINKAGE
key disaccharides
glucose + fructose = SUCROSE
glucose + galactose = LACTOSE
glucose + glucose = MALTOSE
why do polysaccharides cost little energy to build?
dehydration synthesis requires little energy
α glucose polymers
- energy storage molecules
- glycogen (fast release) & starch/amylose (slow release)
- can be digesting by animals
- more branching = more surface area = faster release
β glucose polymers
- structural molecules
- cellulose & chitin
- cannot be digested by animals
how do herbivores digest cellulose
uses special bacteria in elongated guts
what holds polysaccharides together
glycosidic linkages
