26.1.3 Carbohydrates Flashcards
Which statement about carbohydrates is not correct?
A simple sugar molecule, such as glucose or fructose, is a polymer whose components are linked in a long, linear fashion.
Aldehydes and ketones are constituent components of carbohydrates. They are either exposed in the open form of the carbohydrate or they are masked in the closed form of the carbohydrate. The drawing shows how an aldehyde reacts with an alcohol. It also shows the reverse reaction, in which an aldehyde and an alcohol are produced. Which statement about these reactions is not correct?
The OH group in the alcohol product of reaction 2 is the same as the OH group in the reactant of reaction 2.
A glucose sugar molecule has an aldehyde that is masked or hidden in its structure. The diagram shows how a closed form glucose molecule becomes an open form glucose molecule.
Which statement about this event is not correct?
The oxygen atom at the bottom of the closed glucose molecule eventually forms a new OH group in the product molecule.
Look at starch (or amylose) and cellulose polymers.
Which statement about starch or cellulose is not correct?
Both starch and cellulose are comprised of linked glucose molecules. The only difference involves the elements (oxygen versus nitrogen) that actually link the glucose molecules.
Which statement about aldehydes or ketones is not correct?
Ketones and aldehydes are formed from the same types of alcohols.
Carbohydrates are __________________
a class of biological molecules composed of polyhydroxylated aldehydes or ketones.
Ribose is an important sugar component of RNA, which is a nucleic acid involved in protein synthesis in the body. Deoxyribose is an important sugar component of DNA, a nucleic acid that stores the body’s genetic information. Which statement about these carbohydrates is not correct?
The formula for ribose is C5H10O4.
Which statement about carbohydrates is not correct?
Most sugars in equilibrium have a majority of their molecules in the open-chain form in which the aldehyde or the ketone is revealed.
Look at the reaction of an alcohol and an aldehyde. Which statement about this reaction is not correct?
A lone electron pair from the oxygen atom in the aldehyde forms a bond between the oxygen atom in the carbonyl and the hydrogen atom in the aldehyde.
A molecule reacts to form an alcohol and an aldehyde. Which statement about this reaction is not correct?
The hydrogen atom located on the bottom of the reactant molecule breaks its bond with a carbon atom to form a new bond in the product aldehyde molecule.
