Types Of Carbs Flashcards
What kind of color, solubility, and taste to monosaccharides have?
Colorless
Solubility
Sweet tasting
Sucrose is composed of
Alpha glucose-1 and beta fructose-2
Lactose is composed of
Glucose and galactose: Beta 1,4
Maltose is composed of:
Glucose and Glucose: alpha 1,4
- Less sweet
What are the characteristics of glycosidic bond?
Type of covalent bond
- formed by dehydration reactions
- anomeric carbon attack OH of another
- reversible by acid catalyze hydrolysis
What does a glycosyltransferase vs glycosidase do?
Glycosyltransferase > form new glycosidic bonds
Glycosidase > break bonds
Starch
About 1/4 amylose: alpha 1,4 glucose
About 3/4 amylopectin: alpha 1,4 with alpha 1,6 at branch points
Glycogen and is it more branched than amylopectin?
Stored in liver and muscle: breaks down with energy shortage
- Glycogen: 1-4 alpha glucose linear, 1-6 alpha glucose branched
- more branched
Cellulose
- beta 1,4 glucose
- humans can’t break down, source of dietary fiber
Chitin, Chitin, Peptidoglycan
Cellulose: plants
Chitin: fungi
Peptidoglycan: bacteria capsule
What is a way to think of hemiacetal vs hemiketal in terms of drawing?
Draw cyclic glucose and fructose respectively and look at the anomeric carbon
What does the attacking in cyclyzing of carbs?
OH nucleophile attacks carbonyl carbon
What would make a carbonyl carbon of sugar more electrophlic?
Protonation that adds on a positive charge to the oxygen
- this would make the carbonyl carbon more electrophilic as the electrons are pulled more towards the positive oxygen
What carbon OH causes the formation of a furanose vs pyranose?
Carbon 4 OH vs 5 OH intramolecular attack
What is a good LG in glycosidic bond hydrolysis?
Protonating the R group of bond, makes it a good LG
Where does the brown food color from?
Mallard reaction: 140-165 C
- faster in basic (coating pretzels with alkaline solution)
- high temp can create acrylamide
What are the substrates in Maillard reaction?
Reducing sugars
- Reducing agents that become oxidized (aldehydes to COOH)
- Fructose > keto-enol taut
How do disaccharides and polysaccharide work as reducing sugars?
Example?
- if they have free end anomeric carbon
- Ex: maltose and lactose
What carries out redox reactions with reducing sugars? What kind of agent and some examples?
Oxidizing agents: Cu, Ag, Fe
What is the tollen’s test? What color and oxidizing agent is used?
Silver aq > Silver solid, forms silver color film
What is Benedict’s test?
Uses copper sulfate as oxidizing agent
- bright blue (Cu2+) > Cu+ aq > brick red
What is Fehling’s test? Which other test is it similar to?
- similar to Benedict’s Reagant
- Copper oxidizing agent, looks for reduced sugars in the urine to detect high blood glucose levels
