Carbohydrates are one of the four major classes of biomolecules.
The authors describe the chemical nature of carbohydrates in Chapter 11.
They introduce monosaccharides and describe their chemical properties.
Students with a limited background in organic chemistry should review these topics in any standard organic chemistry text since they assume familiarity with the properties of aldehydes, ketones, alcohols, and stereoisomers.
The chapter talks about simple derivatives of monosaccharides.
You can see monosaccharide derivatives in the structures of nucleic acids in Chapter 5 and 9.
Polysaccharides and oligosaccharides are discussed as components of proteoglycans and glycoproteins in the text.
The lysosomes are usually attached to the lysosomal sac.
One reason for attachment of sugars is the targeting of specific proteins to specific sites.
A eucaryotic cell has many different subcellular compartments, each of which has to have a certain array of genes.
Attached sugars can be used as signals for proper folding.
Lectins and selectins bind oligosaccharides on the cell surface.
The A, B, and O blood group antigens are examples of cell surface oligosaccharides.
The flu virus can attach to cells by binding to sialic acid, thanks to Hemagglutinin.
You should be able to complete the objectives once you have mastered this chapter.
Give a Fisher formula and draw a ring structure.
The bonds are indicated by symbols a-1,6 or b-1,4.
Natural sources of these disaccharides should be given.
There are examples of the digestion of carbohydrates in humans.
The attachment of the carbohydrates to the glycoprotein is done with the use of the amino acid residues.
The aldopentoses are shown.
The types of stereoisomers are represented by each pair.
A and B are B and C are A and B.
The properties of D-glucose and D-ribose can be identified.
The monosaccharides are reducing sugars.
Draw the structure of the disaccharide.
A sample of bread has Nelson's reagent in it.
All the descriptions in the right col umn are appropriate for the polysaccharides in the left column.
There are oligosaccharides linked to the side chain of lysine or histidine.
Plants andbacteria produce lectins.
A, c, d. The energy re quirements of the organisms are supplied by most of the carbohydrates in the human diet.
The mass stored is relatively small compared to the other body parts.
The weight of the body is not affected by the carbohydrate present in nucleic acids, glycoproteins, glycolipids, and cofactors.
The a-anomer form of sugars B and D and the b-anomer form of sugar E are the same.
There are two diastereoisomers, B and C. A and C are related.
Both c and d are correct.
The total number of possible kinds of trisaccharides is four since there are two glucosidic bonds in each trisaccharide.
One would be more likely to find three kinds if they found two consecutive a-1,6 bonds.
The bread contains a mixture of polysaccharides with D-glucose linked by glucosidic bonds.
All of the aldehyde groups in the poly saccharide are involved in acetal bonds and do not react with Nelson's reagent.
A1,4 glucosidic bonds are broken by a-amylase in saliva during mastication.
The glucosidic linkages of both cellulose and amylose are b-1,4 whereas those of amylose are a-1,4.
The different configuration at the anomeric carbons affects the orientation of the consecutive glucose residues.
The other antigens have extra galactose or N-acetylgalactosamine, but the O doesn't.
The presence of an unfamiliar "bump" in the shape of an oligosaccharide won't be enough for antibodies to notice.
There are linked oligosaccharides.
The answer is incorrect because dolichol is attached to an oligosaccharide.
Sugar-substituted dolicholphosphates serve as acceptors of monosac charides from other dolicholphosphate sugars and as donors of monosaccharides and oligosaccharides to other dolicholphosphate sugar derivatives.
Dolichol pyrophosphate is formed as a result of the transfer of dolichol.
The compound needs to be s hydrolyzed to dolichol to regenerate the sugar carrier.
The Golgi complex adds to the core oligosaccharides that were constructed in the ER.
The Golgi's compartments are distinct and components are transferred between them.
The disease is caused by a deficiency in a sugarphosphatase that leads to the formation of a mannose 6-phosphate terminus on an oligosaccharide substituent of the eight or more affected lysosomal hydrolases.
The mannose of the oligosaccharide has a GlcNAcphosphate attached to it.
The mannose has aphosphate on it.
The mannose 6-phosphate "address" label is missing from the mannose 6-phosphate "address" label that is exported from the cell.
Fructose and galactose can be found in water at a neutral pH.
In 100 liters of water, over 150 g of sugar can be dissolved.
The following pairs of molecule are enantiomers, epimers, di astereoisomers, or anomers.
D-sorbitol is produced when compound X is reduced using NADPH as an electron donor.
The products of this sugar alcohol are NADH and Y.
Reducing sugars are defined as those with a free alde hyde or keto group that can reduce cupric ion to the cuprous form.
The open-chain form of the aldose is the reactive species in the reducing sugar reaction.
The total amount ofglucose can be estimated using the reaction.
Compare the number of dimers that can be prepared from a pair of alanine molecules and from a pair of D-galactose molecules, each of which has a pyranose ring.
Pairs can be made using the a or b anomers.
Storage polysaccharides have a lot of glu cose units.
The cost of synthesizing is high.
In a liver cell, the glucosyl residues were replaced with an equivalent number of free sugars.
You have a sample of glycogen that you want to analyze.
The sample is subjected to acid hydrolysis, which cleaves the glysidic linkages.
The yield of 2,3-dimethylglucose is determined by you.
The molecule weight of a glycosyl is 162.
One example of the storage oligosaccharides that account for the flatulence caused by eating beans, peas, and other legumes is shown below.
The oligosaccharides cannot be eaten by the small intestine, but they can be eaten by the large intestine.
They oxidize with the production of large quantities of carbon dioxide, hydrogen sulfide, and other gases.
When eaten with the offending legumes, the oligosaccharides can be converted into digestible products.
A name for the oligosaccharide shown above.
The main concern about paper ingestion by pets and small children is the stomach.
MALDI-TOF is a acronym for MatrixAssisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry.
It can't solve oligosaccharide structures without input from other techniques, but it is a highly sophisticated technique.
A qualitative description will do, this is not a quantitative question.
Other sugars had little effect on the agglutination of type A erythrocytes.
It is possible to form hydrogen bonds with water and other polar molecules.
The high degree of hydration of the polyanions, as well as charge repulsion between the sulfate and carboxylate groups, contributes to the tendency of these compounds to resume their normal structures after they have been altered.
The mirror image of a compound is an a compound.
A-L-glucose is the mirror image of a-D-glucose.
The same result would be achieved by the less common sugar Lgulose.
D-aldose is the starting material for sugar alcohols because there is no most-oxidized carbon.
Neither type of ring can be formed by sorbitol.
The only expected result would be that the L-ketose would not be produced by the Enzymes.
There is an equilibrium among three forms of water.
Two-thirds is the b anomer, one-third is the a anomer, and less than 1% is the open-chain form.
The open-chain form of cupric ion reacts with the excess cupric ion.
The law of mass action converts the a and b anomers of glucose into the open-chain aldose form.
The ultimate conversion of all glucopyranoses to the open-chain form is achieved by continued production of gluconic acid.
It is possible to determine the total amount of glucose in a known volume of blood.
Alanylalanine can only be made from two alanine molecules linked together.
The aldehydic function at the C-1 position of each D-galactose molecule provides an opportunity to make a larger number of dimers.
Both the a and b forms of one molecule can have links with the other.
The C-5 position is not available because it participates in the formation of the pyranose ring.
The eight dimers can be added with the help of glycosidic linkages.
There are 11 possible dimers.
If one is allowed to use L forms, there will be more possible dimers.
The sugars are very versatile and can be used in many different ways in biology.
The study of the chemistry of polysaccharides is very difficult because of this variety.
A dramatic increase in osmotic pressure is the primary consequence of a high concentration of free glucose in the cell.
Colligative properties like boiling and freezing points, vapor pressure, and osmotic pressure are dependent on the number of molecules in the solution.
The osmotic pressure of a million molecules of freeglucose is one-millionth that of a glycogen molecule.
In an attempt to equalize pressure inside and outside the cell, highglucose concentration would induce entry of water into the cell.
Unlike plant cells, which have a rigid wall that can help resist high pressures, animal cells have a more fragile wall, which will burst when osmotic pressures are too high.
Only C-2 and C-3 of a branch point will have alcohol or hydroxyl groups that are free.
The 2,3-dimethylglucose is converted at a branch point.
The single glucosyl residues at the reducing end could be converted to 1,2,3,6-trimethylglucose by the same procedure.
10% of the glucosyl is at branch points.
Both a- and b-anomeric linkages are cleaved by acid hydrolysis.
An activity that would be required for the oligosaccharide shown would be a type of a-1,6-glycosidase, which would cleave the a-1,6 linkage between the two sugars.
The b-1,4-fructosidase is a different type ofidase.
Chapter 11 contains oligosaccharides that can be used to free hexoses.
The three sugars shown in this problem are easy to convert to other sugars in the body.
A reduction in the concentration of oligosaccharides can be achieved by inducing hydrolase proteins, which can be used in the developing plant tissues as a source of carbon for synthesis.
As they pass through the GI tract, small amounts of indigestible complex carbohydrates are virtually unchanged.
The large intestine does not produce gases from carbohydrate breakdown.
There are no enzymes that can cleave the glycosidic linkages, which may cause intestinal blockage.
The service of breaking b-1,4 bonds can be provided by organisms that use cellulose as an energy source.
Dolichol pyrophosphate is the intermediate that accumulates.
Bacitracin is an antibiotic that forms a complex with dolichol pyrophosphate.
The label will remain in dolichol pyrophosphate if bacitracin is present.
The terminalphosphate will be released as an insturment if bacitracin is not present.
MALDI-TOFMS only gives an accurate weight for a molecule.
If you have ten sugars, they can be rearranged in many different forms that have the same weight.
Extra information that is critical to the "sequencing" of an oligosaccharide is provided by certain sugars that can only be cleaved in certain positions.
Each free hydroxyl group and anomeric carbon on a particular monosaccharide can be linked to similar groups on adjacent residues in oligosaccharides.
A linear or branched octooligosaccharide could be composed of as many as eight different monosaccharides, each requiring additional steps to analyze completely.
The analysis of an oligonucleotide is less complicated because there are usually only four different bases found, and the linkage between adjacent nucleotides is usually 3' 5'.
Although there may be as many as eight different amino acid residues in an octapeptide, all 20 different amino acids found in most proteins are relatively easy to identify and the octapeptide is unlikely to be branched.
Morgan and Watkins observed that the sugar N-acetylgalactosamine in a linkage is the determinant of blood group A specificity.
The sites that would otherwise bind to glycoproteins are occupied by the galactose derivative on the surfaces of type A cells.
The first papers to establish the structures of the blood group oligosaccharides were written by Winifred M. Watkins.
Early female role models in the fields of Biochemistry and Molecular Biology include Maud Menten, who collaborated with L. Michaelis to study enzymology, and Rosalind Franklin, who de termined the structure of the A-form.
The Royal Society elected Dr. Watkins as a Fellow in 1998.
Although it can be risky, chemists have always tried to gain insight into the structure of the molecule from knowledge of the empirical formula.
There are six ways to specify the order of ride units.
The first glycosidic bond can join the first two monomers in any of 25 or 32 ways, or b from the C1 oxygen of the first sugar to OH #2, 3, 4, or 6 of the second sugar.
The second glycosidic bond can join the second and third monomers in any of 26 or 64 ways, from the C1 oxygen of the second sugar to OH #1 (nonreducing) or #2, 3, 4, or 6 of the third sugar.
One has between six and 64 possible trisaccharides.
There are only 6 different tripeptides that use the same three different amino acids.
To answer this problem, one needs to know the structures of the molecule and some definitions.
An aldose-ketose pair is obvious.
The conclusion is that (a), (c), and (e) are aldose-ketose pairs; (b) and (f) are epimers; and (e) are anomers.
Under alkaline conditions, hemiacetals are converted to aldonic acid.
D-d-gluconolactone is the major first reaction product.
The oxidant used to prepare aldonic acids is usually Br2 because it gives fewer side reactions than Tollens' reagent.
The ring form of a-D-glucopyranose is in equilibrium with a small amount of straight-chain form of glucose, which is the reason the specific rotation of a-D-glucopyranose changes after it is dissolved in water.
The straight-chain form can be converted to either a-D-glucopyranose or b-D-glucopyranose.
Its rotation is 52.7o.
The difference between the equilibrium value and the b anomer is 34o.
More than half of the equilibrium mixture is in the b configuration since the optical rotation of the mixture is closer to the b anomer than it is to the a anomer.
The fraction is 34o / 93.3o.
The b configuration has a fraction of 1 - 0.36.
The inactive hemiacetal ring form is in equilibrium with the active straight-chain free aldehyde.
The Schiff base can be formed by reacting with terminal groups and rearranging to the Hb AIc, which accounts for 3% to 5% of the hemoglobin in normal adult human red cells.
The concentration of the drug may go up due to the elevated concentrations of the drug.
Furanosides have two hydroxyls compared to three for pyranosides.
The formation of acetals is acid-catalyzed.
The anomeric hydroxyl group is replaced in a similar way to the esterification of carboxylic acids.
The carbocation is vulnerable to attack by the oxygen of methanol, which leads to the inclusion of this oxygen into the molecule.
The CH2OH is above the plane of the ring so the pyranosyl forms of D-aldohexoses are there.
OH's above the ring are to the left in the projections, and those below the ring are to the right.
A is b-D-mannose, B is b-D-galactose, and D is b-D-glucosamine.
B-D-fructose can be identified by using the same projection as C. When the CH2OH is attached to the C-5 carbon, the sugar is b.
If the trisac charide unit of the glycoprotein is critical for the interaction, the trisaccharide should be a competitive inhibitor of cell adhesion.
The carbon-1 oxygens cannot be methylated because they are nonreducing.
Most of the carbon 6 hydroxyls can be methylated, but not at the branch points.
The relative proportion of reducing ends will be indicated by the ratio of methylated to nonmethylated C-1 hydroxyls in the final digestion mixture.
There are two acetal linkages in raffinose.
The open-chain aldehyde/alcohol form is given by the hemiacetal of the a anomer.
The open form can be used to close the ring.
The b anomer, a anomer, and a small amount of the open-chain form will form an equilibrium in the water solution.