Biochemistry
8th Edition
ISBN: 9781285429106
Author: Campbell, Mary K., FARRELL, Shawn O.
Publisher: Cengage Learning,
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Chapter 9, Problem 28RE
REFLECT AND APPLY List three mechanisms that relax the twisting stress in helical DNA molecules.
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In 1956, E. P. Kennedy and S. B. Weiss published their study of membrane lipid phosphatidylcholine (lecithin) synthesis in rat
liver. Their hypothesis was that phosphocholine joined with some cellular component to yield lecithin. In an earlier experiment,
incubating 32 P-labeled phosphocholine at physiological temperature (37 °C) with broken cells from rat liver yielded labeled
lecithin. This became their assay for the enzymes involved in lecithin synthesis.
Determine the optimal pH for this enzyme and characterize the enzyme activity at different pH values.
-O-P-O-CH2-CH₁₂-N(CH3)3
Phosphocholine
H₂C-O-C-R
HC-O-C-R2
+
+
+
Cell fraction + ?
HC-O-P-O-CH₁₂-CH₂-N(CH),
O
Phosphatidylcholine
The researchers then centrifuged the broken cell preparation
to separate the membranes from the soluble proteins. They
tested three preparations: whole extract, membranes, and
soluble proteins. Table 1 summarizes the results.
Table 1: Cell fraction requirement for incorporation of
32p-phosphocholine into…
Researchers isolated an unknown substance, X, from rabbit muscle. They determined its structure from the following
observations and experiments.
(a) Qualitative analysis showed that X was composed entirely of C, H, and O. A weighed sample of X was completely oxidized
and the H2O and CO2 produced were measured. This quantitative analysis revealed that X contained 40.00% C, 6.71% H, and
53.29% O by weight.
(b) The molecular mass of X, as determined by mass spectrometry, was 90.00 atomic mass units (u).
(c) Infrared spectroscopy showed that X contained one double bond.
(d) X dissolved readily in water, and the solution demonstrated optical activity when tested in a polarimeter.
(e) The aqueous solution of X is acidic.
What is the empirical formula of X?
Show work. don't give Ai generated solution....give correct solution
Chapter 9 Solutions
Biochemistry
Ch. 9 - REFLECT AND APPLY Consider the following in light...Ch. 9 - Prob. 2RECh. 9 - RECALL What is the structural difference between...Ch. 9 - RECALL Give the name of the base, the...Ch. 9 - RECALL What is the difference between ATP and...Ch. 9 - RECALL Give the sequence on the opposite strand...Ch. 9 - RECALL Are the sequences shown in Question 6 those...Ch. 9 - REFLECT AND APPLY (a) Is it biologically...Ch. 9 - REFLECT AND APPLY A friend tells you that only...Ch. 9 - REFLECT AND APPLY In the early days of molecular...
Ch. 9 - REFLECT AND APPLY Why is RNA more vulnerable to...Ch. 9 - Prob. 12RECh. 9 - RECALL Draw a GC base pair. Draw an AT base pair.Ch. 9 - RECALL Which of the following statements is (are)...Ch. 9 - Prob. 15RECh. 9 - BIOCHEMICAL CONNECTIONS Describe the landmark case...Ch. 9 - Prob. 17RECh. 9 - Prob. 18RECh. 9 - RECALL Which of the following statements is (are)...Ch. 9 - RECALL Define supercoiling, positive supercoil,...Ch. 9 - RECALL What is propeller twist?Ch. 9 - RECALL What is an AG/CT step?Ch. 9 - RECALL Why does propeller-twist occur?Ch. 9 - Prob. 24RECh. 9 - RECALL If circular B-DNA is positively...Ch. 9 - RECALL Briefly describe the structure of...Ch. 9 - Prob. 27RECh. 9 - REFLECT AND APPLY List three mechanisms that relax...Ch. 9 - REFLECT AND APPLY Explain how DNA gyrase works.Ch. 9 - Prob. 30RECh. 9 - REFLECT AND APPLY Would you expect to find...Ch. 9 - REFLECT AND APPLY One of the original structures...Ch. 9 - REFLECT AND APPLY What is the complete base...Ch. 9 - REFLECT AND APPLY Why was it necessary to specify...Ch. 9 - Prob. 35RECh. 9 - Prob. 36RECh. 9 - Prob. 37RECh. 9 - BIOCHEMICAL CONNECTIONS A recent commercial for a...Ch. 9 - REFLECT AND APPLY A technology called PCR is used...Ch. 9 - REFLECT AND APPLY Why does DNA with a high AT...Ch. 9 - Prob. 41RECh. 9 - Prob. 42RECh. 9 - Prob. 43RECh. 9 - Prob. 44RECh. 9 - 45. Why does the absorbance increase when a DNA...Ch. 9 - Prob. 46RECh. 9 - REFLECT AND APPLY Would you expect tRNA or mRNA to...Ch. 9 - REFLECT AND APPLY The structures of tRNAs contain...Ch. 9 - REFLECT AND APPLY Would you expect mRNA or rRNA to...Ch. 9 - REFLECT AND APPLY Which would be more harmful to a...Ch. 9 - Explain briefly what happens to eukaryotic mRNA...Ch. 9 - Prob. 52RE
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