Textbook Question
Researchers design experiments so that only one thing is different between the treatments that are being compared. In the Hershey–Chase experiment, what was this single difference?
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Ch. 15 - DNA and the Gene: Synthesis and Repair
Freeman8th EditionBiological ScienceISBN: 9780138276263
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Table of contents
- Ch. 1 - Biology: The Study of Life13
- Ch. 2 - Water and Carbon: The Chemical Basis of Life14
- Ch.3 - Protein Structure and Function10
- Ch.4 - Nucleic Acids and the RNA World10
- Ch. 5 - An Introduction to Carbohydrates10
- Ch. 6 - Lipids, Membranes, and the First Cells11
- Ch. 7 - Inside the Cell10
- Ch. 8 - Energy and Enzymes: An Introduction to Metabolism10
- Ch. 9 - Cellular Respiration and Fermentation11
- Ch. 10 - Photosynthesis12
- Ch. 11 - Cell-Cell Interactions12
- Ch. 12 - The Cell Cycle8
- Ch. 13 - Meiosis12
- Ch. 14 - Mendel and the Gene23
- Ch. 15 - DNA and the Gene: Synthesis and Repair15
- Ch. 16 - How Genes Work16
- Ch. 17 - Transcription, RNA Processing, and Translation16
- Ch. 18 - Control of Gene Expression in Bacteria16
- Ch. 19 - Control of Gene Expression in Eukaryotes12
- Ch. 20 - The Molecular Revolution: Biotechnology, Genomics, and New Frontiers15
- Ch. 21 - Genes, Development, and Evolution12
- Ch. 22 - Evolution by Natural Selection16
- Ch. 23 - Evolutionary Processes13
- Ch. 24 - Speciation15
- Ch. 25 - Phylogenies and the History of Life13
- Ch. 26 - Bacteria and Archaea15
- Ch. 27 - Diversification of Eukaryotes16
- Ch. 28 - Green Algae and Land Plants16
- Ch. 29 - Fungi18
- Ch. 30 - An Introduction to Animals9
- Ch. 31 - Protostome Animals15
- Ch. 32 - Deuterostome Animals17
- Ch. 33 - Viruses16
- Ch. 34 - Plant Form and Function16
- Ch. 35 - Water and Sugar Transport in Plants16
- Ch. 36 - Plant Nutrition13
- Ch. 37 - Plant Sensory Systems, Signals, and Responses16
- Ch. 38 - Flowering Plant Reproduction and Development16
- Ch. 39 - Animal Form and Function17
- Ch. 40 - Water and Electrolyte Balance in Animals16
- Ch. 41 - Animal Nutrition16
- Ch. 42 - Gas Exchange and Circulation16
- Ch. 43 - Animal Nervous Systems16
- Ch. 44 - Animal Sensory Systems16
- Ch. 45 - Animal Movement11
- Ch. 46 - Chemical Signals in Animals16
- Ch. 47 - Animal Reproduction and Development16
- Ch. 48 - The Immune System in Animals16
- Ch. 49 - An Introduction to Ecology15
- Ch. 50 - Behavioral Ecology16
- Ch. 51 - Population Ecology16
- Ch. 52 - Community Ecology20
- Ch. 53 - Ecosystems and Global Ecology17
- Ch. 54 - Biodiversity and Conservation Ecology18
Chapter 15, Problem 4
Telomerase synthesizes DNA in the _____ direction.
Verified step by step guidance1
Understand the role of telomerase: Telomerase is an enzyme that adds repetitive nucleotide sequences to the ends of chromosomes, known as telomeres, to prevent them from shortening during cell division.
Recognize the direction of DNA synthesis: DNA synthesis typically occurs in the 5' to 3' direction. This means that new nucleotides are added to the 3' end of the growing DNA strand.
Identify the template used by telomerase: Telomerase uses an RNA template that is part of the enzyme itself to extend the 3' end of the DNA strand.
Consider the mechanism of telomerase action: Telomerase binds to the 3' end of the telomere and uses its RNA component to synthesize DNA in the 5' to 3' direction, extending the telomere.
Review the importance of telomerase: By extending telomeres, telomerase plays a crucial role in cellular aging and cancer, as it allows cells to divide without losing important DNA sequences.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Telomerase Function
Telomerase is an enzyme that adds repetitive nucleotide sequences to the ends of chromosomes, known as telomeres. This process helps prevent the loss of important DNA sequences during cell division, thereby maintaining chromosome integrity and stability. Telomerase is particularly active in stem cells and cancer cells, where it supports continuous cell division.
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Functional Groups
DNA Synthesis Direction
DNA synthesis occurs in the 5' to 3' direction, meaning that new nucleotides are added to the 3' end of the growing DNA strand. This directionality is due to the enzymatic mechanism of DNA polymerases, which require a free 3' hydroxyl group to add new nucleotides. Telomerase, like other DNA polymerases, follows this 5' to 3' synthesis rule.
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Telomere Structure
Telomeres are repetitive nucleotide sequences at the ends of linear chromosomes, protecting them from degradation and fusion with neighboring chromosomes. In humans, the sequence is typically TTAGGG, repeated thousands of times. Telomeres shorten with each cell division, and telomerase helps counteract this shortening in certain cell types, contributing to cellular longevity.
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Related Practice
Textbook Question
How does telomerase prevent linear chromosomes from shortening during replication?
Textbook Question
Which of the following is not a property of DNA polymerase?
a. It adds dNTPs only in the 5'→3' direction.
b. It requires a primer to begin synthesis.
c. It opens the two strands of DNA at the replication fork.
d. Its exonuclease activity is involved in proofreading.
Textbook Question
Analyze the following statements about DNA synthesis. Select True or False for each statement.
T/FAn RNA polymerase is essential for DNA synthesis.
T/FOkazaki fragments would be unnecessary if DNA polymerase could synthesize DNA in both the 3'→5' and 5'→3' directions.
T/FDNA ligase is used more frequently on the lagging strand than on the leading strand.
T/FToposiomerase is required to separate the two strands of DNA at the replication fork.
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Textbook Question
What is the function of primase?
a. Synthesis of the repetitive, short double-stranded DNA sequences required by DNA polymerase.
b. Synthesis of a short RNA strand that is complementary to single-stranded DNA.
c. Closing the gap at the 3′ end of DNA after excision repair.
d. Removing primers and synthesizing a short section of DNA to replace them.
Textbook Question
How are Okazaki fragments synthesized?
a. By using the leading-strand template, and synthesizing 5'→3'
b. By using the leading-strand template, and synthesizing 3'→5'
c. By using the lagging-strand template, and synthesizing 5'→3'
d. By using the lagging-strand template, and synthesizing 3'→5'.