BIO 202: Chapter 5

A simple sugar is composed of equal parts carbon and water, which gave rise to the general name of any sugar as a _________.

carbohydrate

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are the α form. Which of the following could amylase break down?

starch and glycogen

What is the major structural difference between starch and glycogen?

the amount of branching that occurs in the molecule

Which feature is shared by all monosaccharides?

In their linear forms, they all contain a carbonyl and several hydroxyl functional groups.

A molecule has the formula C n H2 n O n . What else does it need to be an unmodified monosaccharide?

O bound to every C.

A sugar that has the chemical formula C5H10O5 would be characterized as a(n) _____.

Pentose

Carbohydrates that function as structural molecules are extraordinarily resistant to degradation and decay. Which structural feature is most directly responsible?

Structural polysaccharides are built with β-1,4-glycosidic linkages, which are very resistant to hydrolysis.

Carbohydrates that function as structural molecules withstand pulling and pushing forces well. Which structural feature is most directly responsible?

Structural polysaccharides exist as sets of long, parallel strands that are linked to one another.

The bond that joins two monosaccharides into a disaccharide is a(n) _____.

The glycosidic bond is a covalent bond that joins two sugars together via a condensation reaction.

What happens when glucose forms a ring?

The molecule loses its carbonyl group

Which of the following can vary among monosaccharides?

The number of carbon atoms

What is the LEAST that two molecules can differ, and still be called different kinds of sugars?

The orientation of an OH group differs. In the open-chain form, two sugars may differ in the orientation (right or left) of just one OH group.

Polymers that contain sugars ...

a) may store hereditary information. (b) may store energy. (c) may protect cells.

Which fact is most important in explaining why cellulose is a better structural material than starch?

Alpha-linkages make it easier for the polymer to coil into a helix which is worse for structural use. The alpha links let starch coil into compact helices that pack into dense granules. For structural use, you want polymers that stretch out straight and form cables, as in beta-linked cellulose.

A cotton shirt is chemically most similar to a ...

Cotton shirt because they are both are carbohydrates, made up of suagr

This molecule (glucose) is one member of a large family of related molecules. Members of this family can be found in ...

DNA, ATP, Starch Sugars provide both structure and energy, and are important in the molecules of heredity.

Some sugars differ only in the position of the OH-

Each -OH group can be oriented right or left. Each orientation defines a different sugar with different properties. This makes it possible to build many sugar with the same number of C atoms

Both carbohydrates and fats are used as fuel in cells, but fats store twice as much energy per gram as carbohydrates. Which statement best explains why?

Fats have more C-C and C-H bonds with high potential energy, and fewer C-O bonds with low potential energy.

Which number indicates the sugar that is the principal circulating fuel molecule in the human body?

Glucose, often called blood sugar. It has many other functions too.

A sugar can have ...

H covalently bound to the C of a C=O group

The _____ functional group can always be found in a carbohydrate molecule.

Hydroxyl Carbohydrates are aldehydes or ketones with multiple hydroxyl groups

How do the α and β forms of glucose differ?

Their ring structures differ in the location of a hydroxyl group.

Which of the following structural features is common to cellulose, chitin, and peptidoglycan?

They can all form bonds between polymer chains that create parallel strands.

All carbohydrates have the general formula Cn(H2O)n.

This formula only applies to simple sugars, which are equal parts carbon and water. Complex sugars, which do not have this general formula, are also carbohydrates.

(True/False) Unmodified sugars have formula of CnH2nOn

True

Animal cells store glycogen in granules, and use it for energy.

True

Two sugars can have the same atomic composition but different structures and names

True

Lactose, the sugar in milk, is a _____________, because it can be split into two monosaccharides.

disaccharide

The alpha and beta forms of glucose, found in starch and cellulose, differ in ...

how one of the -OH groups is oriented One particular -OH group points to one side of the ring in alpha glucose; the other side in beta glucose.

A _________ cannot be hydrolyzed any further.

monosaccharide

A carbohydrate that yields many monosaccharides when hydrolyzed is a ___________.

polysaccharide

What is the difference between an aldose sugar and a ketose sugar?

the position of the carbonyl group

Which of the following do starch and cellulose have in common?

the size of their monosaccharide subunits (MONOMER)