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A DNA is placed in a test tube containing fluorescently tagged
| a. | only one DNA molecule would have two fluorescent strands. |
| b. | both strands of each DNA molecule would be half-fluorescent. |
| c. | each DNA molecule would have one fluorescent strand. |
| d. | both DNA molecules would be completely fluorescent. |
Introduction:
DNA is a double-stranded nucleic acid that is responsible for the genetic inheritance. Each strand of DNA is a double helix composed of two antiparallel strands of nucleotides. The complementary nucleotides form hydrogen bonds with each other and hold DNA double helix together.
Answer to Problem 1MCQ
Correct answer:
A DNA is placed in a test tube containing fluorescently tagged nucleotides. DNA replication is induced. After replication, each DNA molecule will have one fluorescent strand. Hence, the correct answer is option c.
Explanation of Solution
Reason for correct answer:
Option c. is given as “each DNA molecule would have one fluorescent strand.”
DNA is the genetic molecule and exhibits a double helix structure. According to Watson and Crick, DNA replication is semi-conservative, which suggests that during replication, one strand of DNA will be original and another will be a new strand. In the presence of fluorescent nucleotides after DNA replication, only the new strand will be fluorescent. Hence, option c. is correct.
Reason for incorrect answer:
Option a. is given as, “only one DNA molecule would have two fluorescent strands.”
During DNA replication one of the DNA strands acts as a template and a new strand is formed over it. Therefore, one DNA molecule will always be nonfluorescent if only one replication cycle happens. Hence, option a. is incorrect.
Option b. is given as, “both strands of each DNA molecule would be half-fluorescent.”
During replication, the new strand is formed based on the original strand. Hence one full strand acting as a template will be nonfluorescent, and the new strands will be fluorescent. Hence, option b. is incorrect.
Option d. is given as, “both DNA molecules would be completely fluorescent.”
Both DNA molecules will be completely fluorescent if multiple replication cycles happen. Still the original DNA strands will be nonfluorescent and will have new fluorescent strands. Hence, option d. is incorrect.
Hence, the options a., b., and d. are incorrect.
DNA replication is semiconservative, which means that during replication the original DNA strand will act as a template and new strand is formed over it. Thus, the correct option is c.
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Chapter 8 Solutions
BIOLOGY:THE ESSENTIALS (LL) W/CONNECT
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