BIOL 2120 Chapter 5: An Introduction to Carbohydrates

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

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

The bond that joins two monosaccharides into a disaccharide is a(n) ________. -Glycosidic bond -Hydrogen bond -Ionic bond -van der Waals bond

Glycosidic bond

Which complex carbohydrate contains only a-1,4-glycosidic linkages? -Cellulose -Glycogen -Amylose -Amylopectin

Amylose

Which of these is a polysaccharide? -Cellulose -Galactose -Sucrose -Lactose -Glucose

Cellulose

_________ is the most abundant organic compound of Earth. -Lactose -Glucose -Cellulose -Starch -Glycogen

Cellulose

Which of these is a source of lactose? -Sugar beets -Milk -Sugar cane -Potatoes -Starch

Milk

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)

Dairy cattle were unknown in Thai culture until recently, and 97 percent of Thai people are lactose intolerant as adults. Which explanation for such widespread lactose intolerance is most likely correct? -The ability to digest sugar in milk is determined by environment, and most humans are not exposed to milk as a food source beyond childhood years -There is no good explanation for this situation in humans -Allergies are becoming more common in humans as more chemicals are being encountered during longer lifetimes -Evolutionarily, producing an enzyme to break down a sugar that will never be encountered is wasteful

Evolutionarily, producing an enzyme to break down a sugar that will never be encountered is wasteful

What holds cellulose molecules together in bundles large enough to form fibers? -Peptide bonds -Hydrogen bonds -Hydrophobic interactions -The cell wall

Hydrogen bonds

Which molecule is not a carbohydrate? -Glycogen -Cellulose -Starch -Lipid

Lipid

Lysozyme, an enzyme found in human saliva, tears, and other secretions, catalyzes the hydrolysis of the b-1,4-glycosidic linkages in peptidoglycan. Predict the effect of this enzyme on bacteria. -Lysozyme has no effect on bacteria -Lysozyme destroys bacterial flagella, leading to the immobilization of the bacteria -Lysozyme destroys bacterial cell walls, leading to the death of the bacteria -Lysozyme destroys the nucleoid, preventing the reproduction of the bacteria

Lysozyme destroys bacterial cell walls, leading to the death of the bacteria

(Second part of #23) Predict how this enzyme may be involved in human health. -Lysozyme helps to protect humans against bacterial infections -Lysozyme helps to digest peptidoglycan in digestive tract -Lysozyme helps to protect humans against viral infections -Lysozyme makes human's saliva, tears, and other excretions sterile

Lysozyme helps to protect humans against bacterial infections

Glucose + glucose -> ________ by ________. -Sucrose + water... dehydration synthesis -Maltose + water... dehydration synthesis -Lactose + water... hydrolysis -Cellulose + water... hydrolysis -Starch + water... dehydration synthesis

Maltose + water.... dehydration synthesis

Which of the following statements about monosaccharide structure is true? -Monosaccharides can be classified according to the spatial arrangement of their atoms -A six-carbon sugar is called a pentose -Aldoses and ketoses differ in the position of their hydroxyl groups -All monosaccharides contain carbon, hydrogen, oxygen, and nitrogen atoms

Monosaccharides can be classified according to the spatial arrangement of their atoms

A sugar that has the chemical formula C5H10O5 would be characterized as a(n)__________. -Hexose -Pentose -Oligosaccharide -Triose

Pentose

Which polysaccharide contains a modified monosaccharide? -Cellulose -Starch -Peptidoglycan -Glycogen

Peptidoglycan

Cellulose, chitin, and peptidoglycan function as structural molecules and withstand pulling and pushing forces well. Which structural feature is most directly responsible? -Structural polysaccharides are built with b1,4-glycosidic linkages that are very strong -Structural polysaccharides are built with b-1,4-glycosidic linkages, which are very resistant to hydrolysis -Structural polysaccharides exist as sets of long, parallel strands that are linked to one another -Structural polysaccharides exist as highly branched helices

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

What is the difference between linking glucose molecules with a a-1,4-glycosidic linkages versus b-1,4-glycosidic linkages? -In b-1,4-glycosidic linkages the glucose monomers are linked in the same orientation -The linkages have different orientation of the glucose monomers -In b-1,4-glycosidic linkages every other glucose is flipped in orientation -In a-1,4-glycosidic linkages the glucose monomers are linked in the same orientation -The linkages are located on opposite sides of the plane of the glucose rings -In a-1,4-glycosidic linkages every other glucose flipped in orientation

The linkages have different orientation of the glucose monomers, in b-1,4-glycosidic linkages every other glucose is flipped in orientation, in a-1,4-glycosidic linkages the glucose monomers are linked in the same orientation, and the linkages are located on opposite sides of the plane of the glucose rings

How could two four-sugar oligosaccharides be structurally different even if both consist of two glucose monomers and two galactose monomers? -The sequence of monomers along the chain or the location and geometry of glycosidic linkages could vary (or both) -Only the sequence of monomers along the chain could vary -One oligosaccharide could contain aldoses while the other contains ketoses Only the location and geometry of glycosidic linkages could vary

The sequence of monomers along the chain or the location and geometry of glycosidic linkages could vary (or both)

True or false? Peptidoglycan is a polysaccharide found only in bacteria.

True

(Second part of #21) What are the consequences? -a-1,4-glycosidic linkages more resist to degradation -a-1,4-glycosidic linkages are much more likely to form linear fibers and sheets -b-1,4-glycosidic linkages more resist to degradation -b-1,4-glycosidic linkages are much more likely to form linear fibers and sheets

b-1,4-glycosidic linkages more resist to degradation, and b-1,4-glycosidic linkages are much more likely to form linear fibers and sheets

Glycogen is _______. -The form in which plants store sugars -A polysaccharide found in plant cell walls -A source of saturated fat -A transport protein that carries oxygen -A polysaccharide found in animals

A polysaccharide found in animals

Carbohydrates, more commonly known as sugars, are made up of carbon, oxygen, and hydrogen atoms. The smallest unit of a carbohydrate is a monosaccharide. Two monosaccharides make up a disaccharide, and many monosaccharides make up a polysaccharide. Disaccharides and polysaccharides can be hydrolyzed back into the individual monosaccharide units. Select the statement that is incorrect. -Complex sugars are carbohydrates -All carbohydrates have general formula Cn(H2O)n -Simple sugars are carbohydrates -Simple sugars contain only carbon, oxygen, and hydrogen atoms

All carbohydrates have the general formula Cn(H2O)n

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 glycogen in the cracker into glucose monomers, which stimulate the sweet receptors in your tongue -Amylase breaks down the starch in the cracker into glucose monomers, which stimulate the sweet receptors in your tongue -Lysozyme breaks down the cellulose in the cracker into glucose monomers, which stimulate the sweet receptors in your tongue -Lysozyme breaks down the starch in the cracker into glucose monomers, which stimulate the sweet receptors in your tongue

Amylase breaks down the starch in the cracker into glucose monomers, which stimulates the sweet receptors in your tongue

A simple sugar is composed of equal parts carbon and wanter, which gave rise to the general name of any sugar as a __________. A carbohydrate that yields many monosaccharides when hydrolyzed is a __________. A __________ cannot be hydrolyzed any further. Lactose, the sugar in milk, is a ___________, because it can be split into two monosaccharides.

Carbohydrate Polysaccharide Monosaccharide Disaccharide

Which of the following complex carbohydrates is listed with its correct function? -Amylose: main component of plant starch -Cellulose: structural component of plant cell walls -Chitin: constituent of bacterial cell walls -Starch: primary energy-storage molecule in animals

Cellulose: structural component of plant cell walls