Skip to main content
Pearson+ LogoPearson+ Logo
Ch. 9 - The Molecular Biology of Translation
All textbooksSanders 3rd EditionCh. 9 - The Molecular Biology of TranslationProblem 5
Chapter 9, Problem 5

A portion of a DNA template strand has the base sequence 5′-...ACGCGATGCGTGATGTATAGAGCT...-3′

Identify the sequence and polarity of the mRNA transcribed from this fragmentary template-strand sequence.

Verified step by step guidance
1
Identify the direction of the DNA template strand, which is given as 5′ to 3′.
Recall that RNA polymerase reads the DNA template strand in the 3′ to 5′ direction, synthesizing mRNA in the 5′ to 3′ direction.
Determine the complementary base pairing rules for transcription: Adenine (A) pairs with Uracil (U) in RNA, Thymine (T) pairs with Adenine (A), Cytosine (C) pairs with Guanine (G), and Guanine (G) pairs with Cytosine (C).
Reverse the given DNA template strand to read it in the 3′ to 5′ direction: 3′-...TCGAGATATGTGCGTACGCACGCA-5′.
Using the base pairing rules, transcribe the mRNA sequence from the reversed DNA template strand, ensuring the mRNA is written in the 5′ to 3′ direction.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
3m
Was this helpful?

Key Concepts

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

Transcription

Transcription is the process by which the genetic information encoded in DNA is copied into messenger RNA (mRNA). During transcription, RNA polymerase binds to the DNA template strand and synthesizes a complementary RNA strand. The RNA is synthesized in the 5' to 3' direction, meaning that the RNA strand will have a polarity opposite to that of the DNA template strand.
Recommended video:
Guided course
09:16
Eukaryotic Transcription

Base Pairing Rules

Base pairing rules dictate how nucleotides pair during the transcription process. In RNA, adenine (A) pairs with uracil (U) instead of thymine (T), which is found in DNA. Therefore, when transcribing a DNA sequence, cytosine (C) pairs with guanine (G), guanine (G) pairs with cytosine (C), adenine (A) pairs with uracil (U), and thymine (T) pairs with adenine (A).
Recommended video:
Guided course
03:49
Base Distortions

Polarity of Nucleic Acids

Nucleic acids, including DNA and RNA, have directionality or polarity, indicated by the 5' and 3' ends. The 5' end has a phosphate group, while the 3' end has a hydroxyl group. This polarity is crucial during transcription, as RNA polymerase adds nucleotides to the 3' end of the growing mRNA strand, resulting in an mRNA molecule that is complementary to the DNA template strand and has a 5' to 3' orientation.
Recommended video:
Guided course
09:49
Point Mutations
Related Practice
Textbook Question

The human mitochondrial genome encodes only 22 tRNAs, but at least 32 tRNAs are needed for cytoplasmic translation. How are all codons in mitochondrial transcripts accommodated by only 22 tRNAs? The Plasmodium mitochondrial genome does not encode any tRNAs; how are genes of the Plasmodium mitochondrial genome translated?

337
views
Textbook Question

Outline the events that occur during initiation of translation in E. coli.

274
views
Textbook Question

Describe the gene and protein defects in phenylketonuria (PKU). How are these defects connected to disease symptoms?

228
views
Textbook Question

A portion of a DNA template strand has the base sequence 5′-...ACGCGATGCGTGATGTATAGAGCT...-3′

Which is the third amino acid added to the polypeptide chain?

300
views
Textbook Question

A portion of a DNA template strand has the base sequence 5′-...ACGCGATGCGTGATGTATAGAGCT...-3′

Assume the mRNA is written in the correct reading frame. Determine the amino acid sequence encoded by this fragment. Identify the N- and C-terminal directions of the polypeptide.

327
views
Textbook Question

What are the differences between the universal code and that found in the mitochondria of some species? Given that some changes (UGA =stop→Trp) have occurred multiple independent times in evolution, can you think of any selective advantage to the mitochondrial code?

314
views