Concept explainers
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.
Want to see more full solutions like this?
Chapter 8 Solutions
BIOLOGY: ESSENTIALS >LL< W/ CONNECT
- DNA replication involves a series of steps, including initiation, making primers, extension, and connecting DNA fragments. The cell uses different enzymes in a particular order to accomplish these steps. Which of the following represents the correct general order of enzyme use? A. DNA polymerases, helicase, primase, ligase B. Helicase, ligase, primase, DNA polymerases C. Helicase, primase, DNA polymerases, ligase D. Primase, helicase, DNA polymerases, ligasearrow_forwardRefer to Figure 2 and compare this with the DNA model in Figure 1. a. In what ways are they similar? b. In what ways are they different? c. What is the biological significance of such differences? Why is the DNA referred to as the genetic material?arrow_forwardDNA replication is said to be semiconservative because a. one of the new molecules conserves both of the original DNA strands. b. the new DNA molecule contains two new DNA strands. c. both of the new molecules contain one new strand and one old strand. d. DNA polymerase conserves both of the old strands.arrow_forward
- Which statement about Okazaki fragments is true? Select one: a. DNA polymerase doesn’t need a primer to build these fragments b. They act as a primer that initiates DNA replication. c. They correct errors made during earlier phases of DNA replication. d. They are necessary because DNA polymerase can only build DNA in the 5’ to 3’ direction, so for one of the strands at each fork, the DNA polymerase can only buildaway from the fork. e. They prevent the ends of chromosomes from shortening with every replication.arrow_forwardDuring DNA replication, the helicase enzyme binds to DNA and Select one: a. prevents the DNA strands from rewinding back into the helical shape b. cuts the double stranded DNA into single strands c. provides the starting point where new nucleotides can be added d. adds new nucleotides to the template strandarrow_forwardPlace the following steps of DNA replication and repair in the correct order by numbering them from 1 to 5. a. A template strand begins to be replicated. b. If the incorrect base is not identified and replaced, it remains as a point mutation in the DNA. c. DNA polymerase identifies and replaces most incorrect bases with the correct base, complementary to the base on the template strand. d. An incorrect base is added to the growing strand of DNA. e. Proteins identify and replace any incorrect bases missed by DNA polymerase.arrow_forward
- The function of DNA ligase is to: a. Catalyze formation of phosphodiester bonds between adjacent nucleotides b. Catalyze formation of hydrogen bonds between adjacent nucleotides c. Keep single strands of DNA apart during replication d. Facilitate base pairing between single stranded molecules in DNA e. Both a. and d. are correctarrow_forwardWhich statement about Okazaki fragments is true? Select one: O a. They are necessary because DNA polymerase can only build DNA in the 5' to 3' direction, so for one of the strands at each fork, the DNA polymerase can only build away from the fork. O b. They correct errors made during earlier phases of DNA replication. O c. They act as a primer that initiates DNA replication. O d. They prevent the ends of chromosomes from shortening with every replication. e. DNA polymerase doesn't need a primer to build these fragments.arrow_forwardThe antiparallel nature of DNA refers to a. its charged phosphate groups. b. the pairing of bases on one strand with bases on the other strand. c. the formation of hydrogen bonds between bases from opposite strands. d. the opposite direction of the two strands of nucleotides.arrow_forward
- Determine whether each statement isTRUE or FALSE.a. In eukaryotic chromosomes, DNA replication begins at a single point in the chromosome and proceeds in two directions.b. The bonds between the sugars and phosphates are broken during DNA replication.c. The elongation of the leading strand during DNA synthesis progresses away from the replication fork.d. Each DNA molecule resulting from replication has one original strand and one new strand.e. The difference in how the leading and lagging strands of DNA molecules are synthesized is due to DNA polymerase adding new nucleotides only to the 3’ end of a growing strand, and the strands are anti-parallel.arrow_forwardWhich of the following statements about nucleic acids is not correct? Select one: A. In DNA the distance between the strands of the double helix is relatively constant. B. The growing DNA polymer is synthesized in the 5' to 3' direction. C. The enzymes that catalyze DNA synthesis are known as DNA polymerases. D. RNA strands are synthesized in the 3' to 5' direction. E. Unlike DNA, RNA is easily cleaved because the 2'-OH group of the ribose is a nucleophile that catalyzes hydrolysis of the strand.arrow_forwardDNA replication is said to be semiconservative becausea. each new DNA molecule contains one new strand and one old one.b. every other new DNA molecule contains two old strands.c. each new DNA strand contains two new strands.d. every other new DNA molecule contains one new strand and one old one.arrow_forward
- Essentials of Pharmacology for Health ProfessionsNursingISBN:9781305441620Author:WOODROWPublisher:Cengage