Concept explainers
Answers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book.
Drawing Structures of Triacylglycerols Draw the structures of (a) all the possible triacylglycerols that can be formed from glycerol with Stearic and arachidonic acid and (b) all the phosphatidylserine isomers that tan be formed from palmitic and linolenic acids.
(a)
To explain:
The formation from glycerol from stearic and arachidonic acid should be described.
Introduction:
Glycerol is the colorless, viscous liquids that belong to the organic group of alcohol. It has three carbon atoms and three hydroxyl groups in its structure that are known as trihydroxyl sugar alcohol.
Explanation of Solution
The chiral molecule is found in the second carbon of glycerol if there is the presence of different substitutes at both ends of carbon. This can lead to the formation of six triacylglycerols from stearic and arachidonic acids as below:
(b)
To explain:
The formation from phosphatidylserine isomers from palmitic and linolenic acids should be described.
Introduction:
A phospholipid with fatty acid is known as phosphatidylserine that covers and protects the cells in the brain and carries messages. It has two fatty acids attached with ester linkage to the C-1 and C-2 of glycerol and serine attached by a phosphodiester linkage to the C-3 of glycerol.
Explanation of Solution
There is a presence of phosphate bonded with a serine residue at C-3 of glycerol in structures of phosphatidylserine. There are two common forms of linolenic acid which means four different phosphatidylserine can be formed from palmitic and linolenic acids as shown below:
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Chapter 8 Solutions
Biochemistry
- Kranse et. al. measured the temperature dependence of conductance using membranescontaining the phospholipids glyceryl dipalmitate and glyceryl distearate. Describe themodifications in membrane content that you would employ to: (a) shift the temperature of the phase transition (b) make the ion conductance curve for valinomycin andnonactin more like that of gramicidinarrow_forwardObtain the sequence for the 5-HT receptor HTR1A and generate a hydropathy plot usingthe ExPASY tool ProtScale, the appropriate window, and the Kyte-Doolittle weightingalgorithm. How many transmembrane domains are present in this receptor? Attach yourhydropathy plot to your assignment.arrow_forwardCompare and contrast the structural features of the ion carrier valinomycin with those of achannel former like gramicidin. How does structural information help explain the mechanismby which these molecules conduct ions across membranes?arrow_forward
- A typical integral membrane protein has a stretch (or stretches) of ~20 hydrophobic aminoacids that form an α-helix that spans the bilayer (as is found in membrane proteins such asglycophorin A and bacteriorhodopsin). Compare and contrast the molecular and structural features of gramicidin with a membrane-spanning α-helix. Explain how gramicidin can forman ion channel when a typical membrane-spanning α-helix cannot (eg, glycophorin A).arrow_forwardThe titration curve of alanine shows the ionization of two functional groups with pK values of 2.34 and 9.69, corresponding to the ionization of the carboxyl and the protonated amino groups, respectively. The titration of di-, tri-, and larger oligopeptides of alanine also shows the ionization of only two functional groups, although the experimental pK values are different. The table summarizes the trend in pK values. Amino acid or peptide Ala Ala-Ala pKj pk₂ 2.34 9.69 3.12 8.30 Ala-Ala-Ala 3.39 8.03 Ala-(Ala)-Ala, n ≥ 4 3.42 7.94 Modify the molecules to show the oligopeptide Ala-Ala-Ala. You can modify the molecules by moving, adding, deleting, or changing atoms, bonds, or charges. C Select c Draw Templates More H с N 0 S Cl H H | | || H CH3 H CH, H CH₂ Complete the statements about the the pK, values of the Ala-Ala-Ala oligopeptide. The pK₁ value of 3.39 is associated with the -COO group of Ala-Ala-Ala. The pK2 value of 8.03 is associated with the -NH group of Ala-Ala-Ala. Erase Q2 Q…arrow_forwardFacts from the bacterium mals and to dept kan apa in a peptide with antidic properties. This peptide complex with the call membrance of other hacterial species, leading in bacterial death The structure of the peptide has been determined from (a) Cmplete acid hydes of the peptide, followed by amino acid analys, yielded quiar anunt of Lan, Om, Pfx, Prxa, and Wall Cmtiti, an amino acid od prosentin pockets but present in some peptides. Com has the tracture H *H,N-CH-CH-CH, -C- COO (b) The weight of the peptide in approximately 1,200 Th (c) The peptide failed to undergo hydrolysis when treated with the Hydrolysis of the carbonyl-terminal residue of a polypeptide une "NH, the year. This call there Pro or the police does not contain a froz (d) Treatment of the peptide with 1-haw-2,4-dicherer (11N1), followed by complete hydrolysis and ched only from and the derivative NO, Н ON NHCHI CH, CH, C coo +NH, (Hint: The 2,4-diphenyl derivative involves the amino group of a side chain rather than the…arrow_forward
- Electrophoresis Macmillan Learning Chymotrypsin is a protease with a molecular mass of 25.6 kDa. The figure shows a stained SDS polyacrylamide gel with a single band in lane I and three bands of lower molecular weight in lane 2. Lane I contains a preparation of chymotrypsin and lane 2 contains chymotrypsin pre-treated with performic acid. 1 2 Why does performic acid treatment of chymotrypsin generate three bands in lane 2? ° Chymotrypsin self-digests on the carboxyl-terminal side of phenylalanine, tryptophan, or tyrosine residues. The three peptides are impurities in the original chymotrypsin sample. Performic acid cleaves proteins on the carboxyl-terminal side of lysine and arginine residues. Performic acid cleaves the disulfide bonds holding together the three subunits of chymotrypsin. Correct Answerarrow_forwardExtracts from the bacterium Bacillus brevis contain a peptide with antibiotic properties. This peptide forms complexes with metal ions and seems to disrupt ion transport across the cell membranes of other bacterial species, leading to bacterial death. The structure of the peptide has been determined from a series of observations. (a) Complete acid hydrolysis of the peptide, followed by amino acid analysis, yielded equimolar amounts of Leu, Orn, Phe, Pro, and Val. Orn is ornithine, an amino acid not present in proteins but present in some peptides. Orn has the structure H 'H,N-CH, - CH2 CH2 CH2 - C - COO- NH, (b) The molecular weight of the peptide is approximately 1,200 Da. (c) The peptide failed to undergo hydrolysis when treated with the enzyme carboxypeptidase. This enzyme catalyzes the hydrolysis of the carboxyl-terminal residue of a polypeptide unless the residue is Pro or the peptide does not contain a free carboxyl group. (d) Treatment of the intact peptide with…arrow_forwardAt a pH equal to the isoelectric point (pl) of alanine, the net charge of alanine is zero. Two structures can be drawn that have a net charge of zero, but the predominant form of alanine at its pl is zwitterionic. CH3 H,N CH3 ** H¸N-C H Zwitterionic H Uncharged OH Select statements that explain why alanine is predominantly zwitterionic at its pl. pk of alanine's amino group is more than its pl. pk of alanine's carboxyl group is more than its pl. PK of alanine's carboxyl group is less than its pl. pk of alanine's amino group is less than its pl. Correct Answer What fraction of alanine is in the completely uncharged form at its pl? 1 in 2.2 × 107 1 in 1.6 × 10² 1 in 4680 1 in 9460arrow_forward
- How does a voltage-gated sodium channel work? Specifically, how and why does a change in voltage trigger their opening? Please be detailedarrow_forwardWhen sodium ions enter a neuron during depolarization, they trigger the opening of additional voltage-gated sodium channels nearby, creating a positive feedback loop where the influx of sodium ions further depolarizes the membrane, causing even more sodium channels to open and allowing more sodium ions to enter the cell, thus sustaining the depolarization process until the action potential peaks. But how and why exactly does the influx of sodium ions trigger more sodium channels to let in more sodium? Please explainarrow_forwardDraw the chemical structure of the tripeptide, HEL (L - amino acids), at pH = 7.0. Calculate isoelectric pointarrow_forward
- BiochemistryBiochemistryISBN:9781305577206Author:Reginald H. Garrett, Charles M. GrishamPublisher:Cengage Learning