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Ch. 9 - The Molecular Biology of Translation
Sanders - Genetic Analysis: An Integrated Approach 3rd Edition
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
All textbooksSanders 3rd EditionCh. 9 - The Molecular Biology of TranslationProblem 39b
Chapter 9, Problem 39b

Answer the following questions about the accompanying diagram.
Diagram illustrating DNA transcription, showing DNA strands labeled A and B, and RNA synthesis with components C, D, E, F, and G.
Which end of the DNA is closest to A?

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1
Examine the accompanying diagram carefully to identify the orientation of the DNA strand. DNA strands have a directionality, typically labeled as 5' (five-prime) and 3' (three-prime) ends.
Recall that the 5' end of a DNA strand has a phosphate group attached to the fifth carbon of the sugar, while the 3' end has a hydroxyl (-OH) group attached to the third carbon of the sugar.
Look for any visual cues in the diagram, such as the presence of a phosphate group or hydroxyl group, to determine the directionality of the DNA strand near point A.
If the diagram includes complementary base pairing, note that DNA strands run antiparallel to each other. This means that if one strand is oriented 5' to 3', the complementary strand will be oriented 3' to 5'. Use this information to infer the orientation of the strand near point A.
Based on the observed features in the diagram, determine whether the end of the DNA closest to point A is the 5' end or the 3' end.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

DNA Structure

DNA is a double helix composed of two strands running in opposite directions, known as antiparallel strands. Each strand has a 5' (five-prime) end and a 3' (three-prime) end, which are crucial for understanding the directionality of DNA. The 5' end has a phosphate group, while the 3' end has a hydroxyl group, influencing how DNA is replicated and transcribed.
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Nucleotide Orientation

Nucleotides, the building blocks of DNA, are linked together by phosphodiester bonds between the 5' phosphate group of one nucleotide and the 3' hydroxyl group of another. This orientation is essential for understanding how DNA strands are synthesized and how they interact with enzymes during processes like replication and transcription.
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DNA Terminology

In molecular biology, the terms '5' end' and '3' end' are used to describe the orientation of the DNA strands. When analyzing a diagram, identifying which end is labeled as 5' or 3' helps determine the direction of the DNA strand and its relationship to other components, such as genes or regulatory elements, which may be crucial for answering questions about the diagram.
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Related Practice
Textbook Question

Organisms of all three domains of life usually use the mRNA codon AUG as the start codon.

Do organisms of the three domains use the same amino acid as the initial amino acid in translation? Identify similarities and differences.

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Textbook Question

Organisms of all three domains of life usually use the mRNA codon AUG as the start codon.

Despite AUG being the most common start codon sequence, very few proteins have methionine as the first amino acid. Why is this the case?

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Textbook Question

Answer the following questions about the accompanying diagram.

Is the DNA nearest A the template strand or the coding strand?

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Textbook Question

Answer the following questions about the accompanying diagram.

What structure is closest to B?

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Textbook Question

Answer the following questions about the accompanying diagram.

What is the name of the molecule closest to C?

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Textbook Question

Answer the following questions about the accompanying diagram.

Which end of the molecule is closest to C?

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