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

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1:46 minutes

Problem 41d

Textbook Question

The two gels illustrated contain dideoxynucleotide DNA-sequencing information for a wild-type segment and mutant segment of DNA corresponding to the N-terminal end of a protein. The start codon and the next five codons are sequenced.

Determine the amino acid sequences translated from these mRNAs.

Verified step by step guidance

Examine the DNA sequencing gels for both the wild-type and mutant segments. Identify the sequence of nucleotides (A, T, G, C) for each strand by reading the gel from bottom to top, as smaller fragments migrate further in the gel.

Convert the DNA sequences obtained from the gels into their corresponding mRNA sequences. Replace thymine (T) in the DNA sequence with uracil (U) to form the mRNA sequence.

Identify the start codon (AUG) in the mRNA sequence, as this marks the beginning of translation. Divide the mRNA sequence into codons (groups of three nucleotides) starting from the AUG codon.

Using the genetic code table, translate each codon into its corresponding amino acid. Continue translating until you encounter a stop codon (UAA, UAG, or UGA), which signals the end of translation.

Compare the amino acid sequences derived from the wild-type and mutant mRNA sequences. Note any differences in the amino acid sequence caused by the mutation, and consider how these changes might affect the protein's function.

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Key Concepts

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

Dideoxynucleotide Sequencing

Dideoxynucleotide sequencing, also known as Sanger sequencing, is a method used to determine the nucleotide sequence of DNA. It involves incorporating dideoxynucleotides, which terminate DNA strand elongation, allowing for the generation of fragments of varying lengths. By analyzing these fragments through gel electrophoresis, researchers can deduce the sequence of the original DNA template.

Codons and Translation

Codons are sequences of three nucleotides in mRNA that correspond to specific amino acids during protein synthesis. The process of translation occurs in ribosomes, where the mRNA is read in sets of codons, and transfer RNA (tRNA) molecules bring the appropriate amino acids to form a polypeptide chain. Understanding codons is essential for translating mRNA into the correct amino acid sequence.

Wild-Type vs. Mutant DNA

Wild-type DNA refers to the normal, non-mutated version of a gene, while mutant DNA contains alterations that may affect gene function. These mutations can lead to changes in the amino acid sequence of proteins, potentially impacting their structure and function. Analyzing both wild-type and mutant sequences is crucial for understanding the effects of genetic variations on protein translation.

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Related Practice

Textbook Question

Diagram a eukaryotic gene containing three exons and two introns, the pre-mRNA and mature mRNA transcript of the gene, and a partial polypeptide that contains the following sequences and features. Carefully align the nucleic acids, and locate each sequence or feature on the appropriate molecule.

a. The AG and GU dinucleotides corresponding to intron-exon junctions
b. The +1 nucleotide
c. The 5' UTR and the 3' UTR
d. The start codon sequence
e. A stop codon sequence
f. A codon sequence for the amino acids Gly-His-Arg at the end of exon 1 and a codon sequence for the amino acids Leu-Trp-Ala at the beginning of exon 2

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Textbook Question

Table D lists α-globin and β-globin gene sequences for the 11 or 12 nucleotides preceding the start codon and the first nucleotide following the start codon (see Problem 34). The data are for 16 vertebrate globin genes reported by Kozak (1987). The sequences are written from -12 to +4 with the start codon sequence in capital letters. Use the data in this table to:

Compare the consensus sequence for these globin genes to the consensus sequence derived from the larger study of 699 vertebrate genes in Problem 34.

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Textbook Question

Determine the consensus sequence for the 16 selected α-globin and β-globin genes.

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Textbook Question

The six nucleotides preceding the start codon and the first nucleotide after the start codon in eukaryotes exhibit strong sequence conservation as determined by the percentages of nucleotides in the to positions and the position (see Problem 34). Use the data given in the table for Problem 35 to determine the seven nucleotides that most commonly surround the start in vertebrates.

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Textbook Question

The two gels illustrated contain dideoxynucleotide DNA-sequencing information for a wild-type segment and mutant segment of DNA corresponding to the N-terminal end of a protein. The start codon and the next five codons are sequenced.

Write out the mRNA sequences encoded by each template strand, and underline the start codons.

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Multiple Choice

In the genetic code, what does the codon UAG specify?

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Multiple Choice

Using the codon chart, which mRNA codon codes for the amino acid methionine in eukaryotes?

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Multiple Choice

Which of the following contains the genetic code?

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