c. In lab, you recorded a UV-Vis spectrum of a mixture of proteins. What bestexplains why two major peaks were observed in your spectrum between240 and 480 nm?i. Amino acids absorb light at two wavelengths depending on theiridentity.The sample was impure.All proteins absorb light at 280 due to the presence of aromaticamino acids and red proteins absorb light near 400 nm.The buffer absorbs light in the visible region and the proteinsabsorb light in the UV region of the spectrum.None of the above.ii.iii.iv.V.d. In lab, you ran an SDS-PAGE gel. What best explains the importance ofadding SDS and heating your samples?i.SDS is a dye used for visualization and heat is used to dissolve theSDS in solution.iii.iv.SDS coats the protein with negative charge and heat aids in theunfolding of the proteins.SDS and heat both help stabilize the proteins during gelelectrophoresis.SDS and heat both help break the peptide bonds of proteins, whichis necessary for gel electrophoresis.

(c). Every substance absorbs a certain amount of energy, when a light of particular intensity…

Answered: c. In lab, you recorded a UV-Vis…

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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Research Center received a protein sample in a liquid form from her colleague recently. However, the colleague did not write down the concentration of the protein in the sample so that Dr. Kim has no idea how much proteins are in the sample. Fortunately, the colleague indicated the extinction coefficient at the maximum absorbance, which is e = 280,000 cm M'. Thus, Dr. Kim measures the absorbance of the sample at different wavelengths with a spectrophotometer using a cuvette with a path length of 15 mm. The measurement result is shown below. What is the concentration of the sample? Plesae assume that there are no other compounds in the sample, except the proteins. 0.6 0.5 0.4 0.3 0.2 0.1 400 600 800 1000 1200 Wavelength (nm) Optical Absorbance
The concentration of protein in a solution can be determined via UV spectroscopy and colorimetry* techniques. Explain further on the statement, give examples of the techniques (please provide three examples for the colorimetry), general principles/mechanism, and general procedures of the techniques. You may use a Table to present the answer. If you need to choose a technique to measure your protein sample, what would be your choice? Justify your answer.
You have purified Protein 'X' and you want to know its concentration. As we learned, you can calculate concentrations by simply measuring UV280 absorbance of protein solutions. Using a UV spectrophotometer, you measured an absorbance of 0.6. Given that Protein X has an absorptivity (or extinction coefficient) of 0.2 mL•mg-cm at 280 nm, what is the concentration of purified protein solution (assume the light path is 1 cm)? -1 O A. 3 g/mL B. 3 mg/mL OC.0.2mg/mL OD.0.2 g/mL OE. 0.6 g/mL
. Suppose you have two genetic variants of a large protein that differ only in that one contains a histidine (side chain pk, = 6.0) when the other has a valine (uncharged side chain). (a) Which would be better for separation: gel electrophoresis or isoelectric focusing? Why? (b) What pH would you choose for the separation?
1. Isoelectric focusing. A digested protein sample was applied to one end of a gel strip with an immobilized pH gradient. According to the experimental image from the results by gel running. Please indicated that what amino acids were compositionally enriched in separated dot 1 and 2? pH 9 Dot An electric field is applied Dot Decreasing pl pH 3 After staining, proteins are shown to be distributed along pH gradient according to their pl values.
Analysis of a protein is taking place. The enzymic acivity of this protein is stable up to temperatures of 40 degrees celsius. ph values are between 2.5 and 11.5. Now, Ion exchange chromatography is conducted via a software using DEAE-cellulose and method of elution is done by salt gradient. pH is set to 7. In terms of Molar, start of gradient is 0 and end of gradient is 1. The following graph is generated. Using the graph and analytical methods, determine pI of protein.
VITATI KEY: Positive charge: Purple, Negative Charge: Pink Hydrophilic: Green Hydrophobic: Brown MOSTU. TOUT um b. Now change the second pull down to oil. What changes? וועען a. Set the first pull down to show charge and hydrophobicity and the second pull down as water. Click generate random protein, and then select random mix (last option). Run the simulation (arrow in center of playbar). What do you notice? (ie What type of amino acid are on the outside?) When you run it again, what is the same and what is different? c. Now change the second pull down to vacuum. What changes? What type of interactions remain? d. Now instead of ‘random mix’, click Mostly hydrophobic and toggle between oil and water. What do you notice? e. Lastly click All hydrophilic and toggle between oil and water. What do you notice? 2. What are the monomers (one subunit) of a polypeptide called? ● On the left half of the space below, draw a simple structure of a protein monomer with uncharged functional groups and…
. Two separate synthetic lipid membranes were prepared using palmitic acid and linoleic acid, singly in each. When both the membranes were tested for their transition temperatures, the one made of palmitic acid showed a higher value than the other. Analyse the situation (
6. Consider the following proteins to answer the questions below: Protein Size (kDa) ε at 280 nm 10 7000 14000 3000 50000 A B C D 50 10 50 pl 4 4 8 8 Red Colored? Yes No No No a. Sketch the UV-Vis spectrum of each pure protein (A, B, C, and D) from 240- 480 nm if they were all present at 20 µM. Note: I want four clearly labeled spectra on one plot.
Analysis of a protein is taking place. The enzymic acivity of this protein is stable up to temperatures of 40 degrees celsius. ph values are between 2.5 and 11.5. Now, size exclusion chromatography is being done. Use the graph below and analytical methods to determine molecular weight of protein.
UV-vis spectroscopy can be used to determine protein and nucleic acid concentrations, provided the user knows the molar extinction coefficient of the protein or nucleic acid. Rank the wavelength absorption for the amino acids below from shortest wavelength to longest in the UV region.
The graph below is a standard curve generated by plotting the distance travelled by the size standards on an SDS-PAGE gel. If a protein band moved to a distance of 2 cm, the approximate Mol. Wt. of that protein is 17 KDa 70 KDa Not enough information 100 KDa

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