Skip to main content
Pearson+ LogoPearson+ Logo
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
Chapter 9, Problem 30e

A DNA sequence encoding a five-amino acid polypeptide is given below.
...ACGGCAAGATCCCACCCTAATCAGACCGTACCATTCACCTCCT...
...TGCCGTTCTAGGGTGGGATTAGTCTGGCATGGTAAGTGGAGGA...
What is the function of the Shine–Dalgarno sequence?

Verified step by step guidance
1
The Shine–Dalgarno sequence is a ribosomal binding site in bacterial mRNA, located upstream of the start codon. It helps recruit the ribosome to the mRNA to initiate translation.
This sequence is complementary to a region of the 16S rRNA within the small ribosomal subunit, allowing the ribosome to align properly with the start codon.
The Shine–Dalgarno sequence ensures that translation begins at the correct location on the mRNA, which is critical for producing the correct polypeptide.
It is typically rich in purines (adenine and guanine) and is found approximately 6-10 nucleotides upstream of the start codon (AUG).
In summary, the Shine–Dalgarno sequence plays a key role in the initiation of translation by guiding the ribosome to the correct start site on the mRNA.

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.

Shine-Dalgarno Sequence

The Shine-Dalgarno sequence is a ribosomal binding site in bacterial mRNA, crucial for initiating translation. It is a short, conserved sequence located upstream of the start codon, allowing the ribosome to recognize and bind to the mRNA. This interaction facilitates the proper alignment of the ribosome with the mRNA, ensuring that translation begins at the correct site.
Recommended video:
Guided course
08:41
Sequencing Difficulties

Translation Initiation

Translation initiation is the first step in protein synthesis, where the ribosome assembles around the mRNA. This process involves the recognition of the start codon (AUG) and the recruitment of the initiator tRNA, which carries the first amino acid. The Shine-Dalgarno sequence plays a vital role in this process by ensuring that the ribosome is positioned correctly to start translating the mRNA into a polypeptide chain.
Recommended video:
Guided course
07:58
Translation initiation

Polypeptide Synthesis

Polypeptide synthesis is the process by which amino acids are linked together in a specific sequence to form proteins. This occurs during translation, where the ribosome reads the mRNA sequence and assembles the corresponding amino acids into a polypeptide chain. The sequence of nucleotides in the mRNA ultimately determines the order of amino acids, which is critical for the protein's structure and function.
Recommended video:
Guided course
02:43
Translesion Synthesis
Related Practice
Textbook Question

A DNA sequence encoding a five-amino acid polypeptide is given below.

...ACGGCAAGATCCCACCCTAATCAGACCGTACCATTCACCTCCT...

...TGCCGTTCTAGGGTGGGATTAGTCTGGCATGGTAAGTGGAGGA...

Give the sequence and polarity of the mRNA encoding the polypeptide.

703
views
Textbook Question

A DNA sequence encoding a five-amino acid polypeptide is given below.

...ACGGCAAGATCCCACCCTAATCAGACCGTACCATTCACCTCCT...

...TGCCGTTCTAGGGTGGGATTAGTCTGGCATGGTAAGTGGAGGA...

Give the polypeptide sequence, and identify the N terminus and C terminus.

623
views
Textbook Question

A DNA sequence encoding a five-amino acid polypeptide is given below.

...ACGGCAAGATCCCACCCTAATCAGACCGTACCATTCACCTCCT...

...TGCCGTTCTAGGGTGGGATTAGTCTGGCATGGTAAGTGGAGGA...

Assuming the sequence above is a bacterial gene, identify the region encoding the Shine–Dalgarno sequence.

559
views
Textbook Question

A portion of the coding strand of DNA for a gene has the sequence

5′-...GGAGAGAATGAATCT...-3′

Write out the template DNA strand sequence and polarity as well as the mRNA sequence and polarity for this gene segment.

924
views
Textbook Question

A portion of the coding strand of DNA for a gene has the sequence

5′-...GGAGAGAATGAATCT...-3′

Assuming the mRNA is in the correct reading frame, write the amino acid sequence of the polypeptide using three-letter abbreviations and, separately, the amino acid sequence using one-letter abbreviations.

1312
views
Textbook Question

A eukaryotic mRNA has the following sequence. The 5' cap is indicated in italics (CAP), and the 3' poly(A) tail is indicated by italicized adenines.

5′-CAPCCAAGCGUUACAUGUAUGGAGAGAAUGAAACUGAGGCUUGCCACGUUUGUUAAGCACCUAUGCUACCGAAAAAAAAAAAAAAAAAAAAAAAA-3′

Locate the start codon and stop codon in this sequence.

792
views