Bio Chapter 5

When cells need energy, reactions break down __________ in the cell and capture the released energy by synthesizing __________.

glucose; ATP

Carbohydrates are important in __________.

supplying sugars found in DNA and RNA

What monomers comprise a glycoprotein, and what is a glycoprotein's function in the cell?

Amino acids and monosaccharides; cell identification

If you hold a salty cracker in your mouth long enough, it will begin to taste sweet. What is responsible for this change in taste?

Amylase breaks down the starch in the cracker into glucose monomers that taste sweet.

What is an important function of glycoproteins in animal cells?

Glycoproteins are important in cell-cell recognition.

What two monomers link to form lactose?

β-galactose and β-glucose

Carbohydrates are made up of which of the following monomers?

Monosaccharides

Which monomers link to form starch?

α-glucose, all with the same orientation

Polymers that contain sugars ... a) may store hereditary information (b) may store energy (c) may protect cells Both (b) and (c) (a), (b), and (c)

(a), (b), and (c)

Which of the following is an energy-storage molecule in plants?

Amylopectin

What is the major difference between amylose and amylopectin?

Amylose is a straight-chain polymer of glucose, whereas amylopectin is highly branched

Which of the following two bonds has the greater amount of potential energy and why? C-C, C-H, or C-O

C-C and C-H because carbon and hydrogen and carbon and carbon share the electrons equally

Three monomers link together to make glycogen. What is the chemical formula of the glycogen product?

C18H32O16

Which chemical formula could represent a monosaccharide?

C3H6O3

If one monomer has the structure C6H12O6 and the other C3H6O3, what is the structural formula of the resulting disaccharide?

C9H16O8

What are the primary functions of carbohydrates in cells?

Cell identity, energy storage, raw material source for synthesis, and structure

Carbohydrates have a variety of functions. Which polysaccharide helps fecal material move through the intestinal tract, thus preventing constipation?

Cellulose

Which of the following carbohydrates has a structural role?

Cellulose

Which of the following molecules is a structural carbohydrate in plants?

Cellulose

How is the structure of cellulose different from that of chitin?

Cellulose is made of β-glucose monomers linked in an alternating chain, whereas chitin is made of N-acetylglucosamine (NAG) monomers linked in an alternating chain.

How is the structure of cellulose different from that of peptidoglycan?

Cellulose is made of β-glucose monomers, whereas peptidoglycan is made of two monosaccharide monomers, one of which is modified by amino acid chains.

Which of the following polysaccharides contains a modified monosaccharide?

Chitin or Peptidoglycan

Which of the following statements accurately compares the different polysaccharides?

Chitin, cellulose, and peptidoglycan consist of long, parallel strands linked to one another.

Which carbohydrate is involved in the storage of energy?

Glycogen

How is a glycoprotein different from glycogen?

Glycoproteins are proteins bound to small carbohydrate chains of many different types, whereas glycogen is always made of glucose monomers and does not contain protein.

What element is essential for forming chitin and peptidoglycan but not starch or cellulose?

Nitrogen

Which cell types have the same glycoproteins on their surfaces?

None; each cell type has distinctive glycoproteins on its surface.

What kind of bond connects two monomer subunits of glucose?

Nonpolar covalent

How is the structure of starch different from that of cellulose?

Starch has α-glucose monomers, whereas cellulose has β-glucose monomers.

Relate the positions of electrons in the C-H bonds in carbohydrates to potential energy. Which of the following statements explains the energy potential?

The electrons involved in the C-H bonds in carbohydrates are shared equally because the electronegativity of carbon and hydrogen is about the same. Thus, these electrons have relatively high potential energy.

Which of the following factors differentiates monosaccharides?

The location of the carbonyl group and The number of carbons in the chain

What differentiates glucose from galactose?

The spatial orientation of the hydroxyl group on the number four carbon

Galactosemia is a potentially fatal disease that occurs in humans who lack the enzyme that converts galactose to glucose. If you were a physician treating a person with this disease, which of the following would you have them exclude from their diet?

lactose

glucose + glucose —> _____ by _____.

maltose + water ... dehydration synthesis

Which of these is a source of lactose? starch potatoes sugar cane milk sugar beets

milk

What are three ways monosaccharides differ from one another? the number of carbon atoms they contain the number of monomers in the molecule the orientations of the C-1 hydroxyl the orientations of their hydroxyl groups the type of glycosidic linkage the location of their carbonyl group

the location of their carbonyl group, the orientations of their hydroxyl groups, the orientations of their hydroxyl groups

Which of the following types of molecules would have the highest capacity to store chemical energy?

A six-carbon molecule rich in C-H bonds, such as a lipid (high number of non-polar bonds)

Which of the following statements demonstrates the relationship between structure and function? Peptidoglycan's structure of two types of monosaccharides linked by β-1, 4-glycosidic linkages, and amino acids provides strength and firmness to bacterial cell walls. Chitin is a polymer of β-glucose monomers whose flipped orientation gives plant cells structural support. Cellulose is a polymer of N-acetylglucosamine (NAG) monomers with a flipped orientation that provides stiffness and support in fungi. Glycogen's highly branched α-glucose structure allows for polysaccharide storage in plants. Starch's α-glucose monomers joined by glycosidic linkages with branched and unbranched components allow for carbohydrate storage in animals.

Peptidoglycan's structure of two types of monosaccharides linked by β-1, 4-glycosidic linkages and amino acids provides strength and firmness to bacterial cell walls.

You believe a bacterium is attaching to animal cells by binding to the carbohydrate portion of a specific glycoprotein. To test this hypothesis you pre-incubate the bacteria with various molecules and then test for inhibition of attachment to the animal cells. Which result supports the hypothesis that the bacteria recognize the carbohydrate component of the animal glycoprotein?

Pretreatment with the carbohydrate component alone prevents bacteria attachment to the animal cells.

The storage form of carbohydrates in animals is __________; and in plants, it is __________.

glycogen; starch

What type of bond is formed between two sugars in a disaccharide?

glycosidic linkage

Which of the following is not a direct end product of photosynthesis or a derivative of a product of photosynthesis?

Glycogen

Which of these carbohydrates has the most branching?

Glycogen

What is the name of the bond connecting two monomer subunits in a carbohydrate?

Glycosidic linkage

What holds chitin molecules together to be able to form a stiff protective armor in some animals?

Hydrogen bonds

Which of the two bonds has the greater amount of potential energy, C=O or C-H?

C-H because the electrons are equally shared

Three monomers link together to make cellulose. What is the chemical formula of the cellulose product?

C18H32O16

Relate the positions of electrons in the C-C bonds in carbohydrates to potential energy. Which of the following statements explains the energy potential?

Electrons are shared equally in the C-C bonds in carbohydrates, meaning they have relatively high potential energy.

Which of the following classes of macromolecules always contains a carbohydrate portion? Water Lipids Nucleic acids Proteins

Nucleic acids

Glycoproteins are important in cell-cell recognition. Where are the carbohydrate portions of these molecules normally found?

On the exterior surface of the cell membrane

What is the difference between peptidoglycans, which are found in the cell walls of prokaryotes, and chitin, which are found in the exoskeletons of insects?

Parallel strands of glucosamines in chitin are cross-linked by hydrogen bonds, whereas parallel strands of peptidoglycan are linked by peptide bonds.

_________ are enzymes that help catalyze the hydrolysis of α-glycosidic bonds in glycogen, whereas ________ are enzymes that help catalyze the hydrolysis of α-glycosidic bonds in starch.

Phosphorylases; amylases

Lysozyme, an enzyme found in human saliva, tears, and other secretions, catalyzes the hydrolysis of the ββ-1,4-glycosidic linkages in peptidoglycan. Predict the effect of this enzyme on bacteria.

The peptidoglycan in bacterial cell walls begins to degrade, leading to the death of the bacteria and protecting against bacterial infections.

Carbohydrates are able to store sunlight as chemical energy. Relate the positions of electrons in the C-O bonds in the hydroxyl groups of carbohydrates to potential energy. Which of the following statements explains the energy potential?

There is relatively low potential energy in the C-O bond in the hydroxyl groups of carbohydrates because of oxygen's high electronegativity.

Which of the following is a way that the various types of carbohydrates you ate during breakfast today are being used in your body right now?

They are broken down to produce ATP and raw materials for building other molecules.

Simple sugars can differ from one another in which of the following ways?

They can differ in the location of their carbonyl group.

How do the hexoses glucose and galactose differ from one another?

They differ in the spatial arrangement of their hydroxyl groups.

Glycogen is _____.

a polysaccharide found in animals

Which of these is a polysaccharide? sucrose cellulose lactose galactose glucose

cellulose

_____ is the most abundant organic compound on Earth.

cellulose

Termites are insects known for their unusual ability to eat wood as a food source. Wood is composed of dead plant cells (mostly secondary xylem) that have thick cell walls. Almost all of the other cell components are gone. Termites cannot breakdown the cell walls because they do not possess the appropriate enzyme; however, they have symbiotic microbes in their digestive tracts that do. The microbes can breakdown the cell walls and share the components with the termite. What carbohydrate are the microbes digesting and what kind of enzyme do they need?

cellulose; an enzyme to hydrolyze β-1,4-glycosidic bonds

What holds cellulose molecules together in bundles large enough to form fibers?

hydrogen bonds

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

hydroxyl

The predominant form of glucose dissolved in an aqueous solution is __________.

the ring configuration

Starch and cellulose are both glucose polymers. Why can animals easily degrade starch but not cellulose?

Animals have the enzymes to degrade α-1,4-glycosidic bonds but not β-1,4-glycosidic bonds.

Glycoproteins are an important component of cell-cell communication, including recognition and signaling. The carbohydrate portion of a glycoprotein is usually a short, branched oligosaccharide because they are diverse in geometry and composition. In the experiment investigating cell-cell recognition between egg and sperm during fertilization, what part of egg-surface glycoproteins was recognized by sperm?

Carbohydrate portion

Fiber is the common name for a polysaccharide with β-glucose monomers that humans cannot digest. Which carbohydrate is it?

Cellulose

From the molecular formula, what would indicate that a six-carbon sugar is a disaccharide composed of two trioses and not a hexose?

In the disaccharide, the molecular formula would be C6H10O5.

Which of the following can be used to distinguish monosaccharides from one another? The number of carboxyl groups and whether they are nonpolar The number of carbon atoms and whether it contains oxygen atoms The number of carbon atoms they contain and the orientations of their hydroxyl groups The number of nitrogen atoms and their polarity

The number of carbon atoms they contain and the orientations of their hydroxyl groups

Predict how the structure of cellulose would change if all of the ββ-1,4-glycosidic linkages were changed to αα-1,4-glycosidic linkages.

The ⍺-glucose residues would all be oriented the same, and the molecule would coil into a helix.

Which of the differences listed here could be found among molecules of the same monosaccharide? There is a difference in the number of carbons. There is a difference in the orientation of a hydroxyl group in the ring form. There is a difference in the sequence of hydroxyl groups. There is a difference in the position of the carbonyl group in the linear form.

There is a difference in the orientation of a hydroxyl group in the ring form.

Which of the differences listed here could be found among molecules of the same monosaccharide? a difference in the orientation of a hydroxyl group in the ring form a difference in the number of carbons a difference in the overall shape of the molecule −− one is a ring and the other is linear a difference in the position of the carbonyl group in the linear form a difference in the orientation of a hydroxyl group in the linear form

a difference in the orientation of a hydroxyl group in the ring form, a difference in the overall shape of the molecule −− one is a ring and the other is linear

Disaccharides are formed by joining together two monosaccharides in condensation reactions. For example, sucrose (table sugar) is composed of glucose and fructose. The bond formed between these monomers is called __________.

a glycosidic linkage

If a monosaccharide's carbonyl group is on an internal carbon, then the monosaccharide is __________.

a ketose

A sugar that has the chemical formula C5H10O5 would be characterized as _____.

a pentose

The extensive hydrogen bonding found among parallel glucose polymers of cellulose enables it to function in plants as a(n) __________.

structural polysaccharide

Polysaccharides probably did not play an important role in the origin of life because __________.

they cannot serve as a template for replication

Monosaccharides differ from one another in __________.

whether they contain an aldose or a ketose group

Which monomers link to form cellulose?

β-glucose, with alternating orientations