Carbohydrates Flashcards
At equilibrium in solution, D-glucose consists of a mixture of anomers. Which statement most accurately describes the solution?
A) consists of approximately equal amounts of alpha and beta anomers
B) the alpha and beta anomers are not freely inter convertible, due to the presence of steric hindrance of the OH groups
C) the alpha anomer is less stable and less preferred than the beta anomer, due to presence of steric hindrance of OH groups below the ring
D) the alpha anomer predominates over the beta anomer by a ratio of approximately 2.1
C) the alpha anomer is less stable and less preferred than the beta anomer, due to presence of steric hindrance of OH groups below the ring
The transformation of a monosaccharide into its …. Occurs easily and does not require the assistance of a catalyst
A) sugar phosphate
B) stereoisomer
C) anomer
D) sugar alcohol
C) anomer
What are the oxidation state of the anomeric carbon before and after cyclization?
A) 0,+1
B)+1,+1
C)0,0
D)+1,0
B)+1,+1
Define different classes of carbohydrates
Atoms of carbon, hydrogen and oxygen combine to form a basic carbohydrate.
General formula = CH2O where n ranges from 3 to 7 carbons
The classes are monosaccharides, disaccharides, oligosaccharides and polysaccharides
Provide examples of each class of carbohydrates
Monosaccharides:
-glucose, fructose, galactose
Oligosaccharides:
-maltose, sucrose, lactose
Polysaccharides: form during dehydration synthesis
-starch, glycogen, cellulose
Identify the reducing sugar
A reducing sugar is any sugar that can reduce Cu+ to Cu+
A simple way to check for free aldehydes or keto groups
Explain the claim ´not all conbohydrates are physiological equal´
List the function of carbohydrates
They act as an energy source, help control blood glucose and insulin metabolism
Store and provide energy, and in a couple of very important cases, provide structure to the organism.
Except for ….. and a small amount of …. From animal origin, plants provide the carbohydrate source in the human diet.
Lactose
Glycogen
What are monosaccharides, give a brief description of the types?
Monosaccharides are the basic unit of carbohydrates
-glucose: dextrose or blood sugar, carbon compound formed in food or in the body though digestion. When oxidized it provides energy that is stored as fat in the edipous tissue. In excess is stored as glycogen
What are the similarities and differences between stretch, fiber and glycogen?
Starch is the storage of carbohydrate in plants. They are separated into amylose and amylopectin
Fiber is a major polysaccharide of glucose found in plants. Structural sole rather than nutricional role
What are the health benefits of fiber?
Normalize bowel movements, helps control blood sugar levels, lowers cholesterol levels
Tagatose is an ´artificial´sweetener that is similar in sweetness and replaces sucrose in Pepsi slurped. Tagatose is a steroisomer of fructose.
Only about 30% of tagatose is absorbed in the small intestine; effectively tagatose has 30% of the calories of glucose
A) why does the identity of tagatose as an ´artificial´weetener have a quotation mark on it?
B)why is tagatose absorbed less efficiently?
A) tagatose is by definition a real sugar (CH2O)
B) tagatose is an isomer, the body absorbs them by transporters of fructose si its as efficient.
Lactose and sucrose are commonly found in baby formula milk as the major carbohydrate sources. Based on what you know about these two disaccharides, answer the following questions:
A)despite the popularization of baby formula, doctors still recommend feeding the infants with mothers milk. Why is that?
B)what are the two roles in the mothers milk?
A) because of HMO(human milk oligosaccharides) and because the mothers milk has immunoglobulins and they are transmitted
B) energy and base of HMO (base of many nutrients because its very dominant)
