Table of contents

1. Introduction to Genetics51m
2. Mendel's Laws of Inheritance3h 37m
3. Extensions to Mendelian Inheritance2h 41m
4. Genetic Mapping and Linkage2h 28m
5. Genetics of Bacteria and Viruses1h 21m
6. Chromosomal Variation1h 48m
7. DNA and Chromosome Structure56m
8. DNA Replication1h 10m
9. Mitosis and Meiosis1h 34m
10. Transcription1h 0m
11. Translation58m
12. Gene Regulation in Prokaryotes1h 19m
13. Gene Regulation in Eukaryotes44m
14. Genetic Control of Development44m
15. Genomes and Genomics1h 50m
16. Transposable Elements47m
17. Mutation, Repair, and Recombination1h 6m
18. Molecular Genetic Tools19m
- Genetic Cloning
  9m
- Methods for Analyzing DNA
  9m
19. Cancer Genetics29m
- Overview of Cancer
  21m
- Cancer Mutations
  7m
20. Quantitative Genetics1h 26m
21. Population Genetics50m
- Hardy Weinberg
  19m
- Allelic Frequency Changes
  31m
22. Evolutionary Genetics29m

11. Translation

The Genetic Code

Genetics

11. Translation

The Genetic Code

Previous problemNext problem

3:35 minutes

Problem 30d

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.

Verified step by step guidance

Identify the Shine–Dalgarno sequence, which is a ribosome-binding site in bacterial mRNA. It is typically located upstream of the start codon (AUG) and is rich in purines (adenine and guanine).

Examine the given DNA sequence for regions that could correspond to the Shine–Dalgarno sequence. Remember that the Shine–Dalgarno sequence is complementary to a region of the 16S rRNA and often contains the consensus sequence 5'-AGGAGG-3'.

Determine the mRNA sequence by transcribing the given DNA sequence. Use the coding strand (5' to 3') to generate the mRNA sequence, replacing thymine (T) with uracil (U).

Search the mRNA sequence for a region upstream of the start codon (AUG) that matches or closely resembles the Shine–Dalgarno consensus sequence.

Once the Shine–Dalgarno sequence is identified, note its position relative to the start codon and confirm that it is located within the typical range (approximately 3-10 nucleotides upstream of the AUG codon).

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

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 typically located upstream of the start codon and is complementary to a sequence in the 16S rRNA of the ribosome, facilitating the assembly of the ribosome on the mRNA. This sequence ensures that the ribosome correctly identifies the start site for protein synthesis.

Translation Initiation

Translation initiation is the first step in protein synthesis, where the ribosome assembles around the mRNA. In bacteria, this process begins when the ribosome binds to the Shine-Dalgarno sequence, positioning the start codon in the ribosomal P site. This step is essential for the accurate translation of the genetic code into a polypeptide chain.

Bacterial Gene Structure

Bacterial genes are typically organized in operons, which are clusters of genes transcribed as a single mRNA molecule. The structure includes regulatory sequences, such as promoters and the Shine-Dalgarno sequence, that control gene expression. Understanding this organization is vital for identifying functional elements within a given DNA sequence.

Watch next

Master The Genetic Code with a bite sized video explanation from Kylia

Start learning

Related Videos

Related Practice

Textbook Question

Shown here are the amino acid sequences of the wild-type and three mutant forms of a short protein.

___________________________________________________

Wild-type: Met-Trp-Tyr-Arg-Gly-Ser-Pro-Thr

Mutant 1: Met-Trp

Mutant 2: Met-Trp-His-Arg-Gly-Ser-Pro-Thr

Mutant 3: Met-Cys-Ile-Val-Val-Val-Gln-Hi

___________________________________________________

Use this information to answer the following questions:

For each mutant protein, determine the specific ribonucleotide change that led to its synthesis.

389

views

Textbook Question

Shown here are the amino acid sequences of the wild-type and three mutant forms of a short protein.

___________________________________________________

Wild-type: Met-Trp-Tyr-Arg-Gly-Ser-Pro-Thr

Mutant 1: Met-Trp

Mutant 2: Met-Trp-His-Arg-Gly-Ser-Pro-Thr

Mutant 3: Met -Cys-Ile-Val-Val-Val-Gln-His

___________________________________________________

Use this information to answer the following questions:

Another mutation (mutant 4) is isolated. Its amino acid sequence is unchanged from the wild type, but the mutant cells produce abnormally low amounts of the wild-type proteins. As specifically as you can, predict where this mutation exists in the gene.

1051

views

Textbook Question

Shown here are the amino acid sequences of the wild-type and three mutant forms of a short protein.

___________________________________________________

Wild-type: Met-Trp-Tyr-Arg-Gly-Ser-Pro-Thr

Mutant 1: Met-Trp

Mutant 2: Met-Trp-His-Arg-Gly-Ser-Pro-Thr

Mutant 3: Met-Cys-Ile-Val-Val-Val-Gln-Hi

___________________________________________________

Use this information to answer the following questions:

Of the first eight wild-type triplets, which, if any, can you determine specifically from an analysis of the mutant proteins? In each case, explain why or why not.

478

views

Textbook Question

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

...ACGGCAAGATCCCACCCTAATCAGACCGTACCATTCACCTCCT...

...TGCCGTTCTAGGGTGGGATTAGTCTGGCATGGTAAGTGGAGGA...

What is the function of the Shine–Dalgarno sequence?

441

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.

565

views

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.

625

views

Textbook Question

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

...ACGGCAAGATCCCACCCTAATCAGACCGTACCATTCACCTCCT...

...TGCCGTTCTAGGGTGGGATTAGTCTGGCATGGTAAGTGGAGGA...

Locate the sequence encoding the five amino acids of the polypeptide, and identify the template and coding strands of DNA.

504

views

Textbook Question

The genetic code is degenerate. Amino acids are encoded by either 1, 2, 3, 4, or 6 triplet codons. An interesting question is whether the number of triplet codes for a given amino acid is in any way correlated with the frequency with which that amino acid appears in proteins. That is, is the genetic code optimized for its intended use? Some approximations of the frequency of appearance of nine amino acids in proteins in E. coli are given in the following:

How would you proceed with your analysis if you wanted to pursue this problem further?

639

views

Show more practices