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Ch.11 Nucleic Acids Big Molecules with a Big Role
Frost - General, Organic and Biological Chemistry 4th Edition
Frost4th EditionGeneral, Organic and Biological ChemistryISBN: 9780134988696Not the one you use?Change textbook
All textbooksFrost 4th EditionCh.11 Nucleic Acids Big Molecules with a Big RoleProblem 40f
Chapter 7, Problem 40f

Consider the following portion of mRNA produced by the normal order of DNA nucleotides:
5'ACA|UCA|CGG|GUA3'
f. What happens to the protein sequence if the A is removed from the beginning of the chain and the sequence changes to 5'CAU|CAC|GGG3'?

Verified step by step guidance
1
Step 1: Understand the problem. The question involves a mutation in the mRNA sequence caused by the removal of a nucleotide (A) at the beginning of the chain. This results in a frameshift mutation, which alters the reading frame of the codons.
Step 2: Recall that mRNA is read in groups of three nucleotides called codons, each of which codes for a specific amino acid. The original sequence is 5'ACA|UCA|CGG|GUA3', and the codons are ACA, UCA, CGG, and GUA.
Step 3: Analyze the mutated sequence. When the A is removed, the sequence becomes 5'CAU|CAC|GGG3'. The new codons are CAU, CAC, and GGG. Notice that the removal of the A shifts the reading frame, changing the grouping of nucleotides.
Step 4: Determine the amino acids coded by the original sequence and the mutated sequence. Use the genetic code chart to translate each codon into its corresponding amino acid. For example, ACA codes for threonine, UCA for serine, etc., in the original sequence. In the mutated sequence, CAU codes for histidine, CAC for histidine, etc.
Step 5: Compare the protein sequences. The frameshift mutation caused by the removal of the A changes the amino acid sequence, potentially altering the structure and function of the resulting protein. This can have significant biological consequences depending on the role of the protein.

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Key Concepts

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

mRNA and Codons

mRNA, or messenger RNA, is a single-stranded molecule that carries genetic information from DNA to the ribosome, where proteins are synthesized. The sequence of nucleotides in mRNA is read in sets of three, known as codons, each of which corresponds to a specific amino acid. Understanding how codons are formed and how they translate into amino acids is crucial for analyzing changes in protein sequences.
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Transcription: mRNA Synthesis Concept 1

Frameshift Mutation

A frameshift mutation occurs when nucleotides are added or removed from the DNA or RNA sequence, altering the reading frame of the codons. This can lead to a completely different translation of the amino acid sequence downstream of the mutation. In the given question, removing the 'A' from the mRNA changes the reading frame, potentially resulting in a different protein product.

Protein Synthesis

Protein synthesis is the biological process through which cells generate new proteins, involving transcription and translation. During transcription, DNA is converted into mRNA, and during translation, ribosomes read the mRNA codons to assemble amino acids into a polypeptide chain. Changes in the mRNA sequence, such as those caused by mutations, can significantly affect the structure and function of the resulting protein.
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Overview of Protein Synthesis Concept 1
Related Practice
Textbook Question

Consider the following portion of mRNA produced by the normal order of DNA nucleotides:

5'CUU|AAA|CGA|GUU3'

c. Write the amino acid sequence if a mutation changes CGA to AGA. Is this likely to affect protein function?

Textbook Question

Consider the following portion of mRNA produced by the normal order of DNA nucleotides:

5'CUU|AAA|CGA|GUU3'

e. What happens to the protein sequence if an A is added to the beginning of the chain and the sequence changes to 5'ACU|UAA|ACG|AGU3'?

Textbook Question

Consider the following portion of mRNA produced by the normal order of DNA nucleotides:

5'ACA|UCA|CGG|GUA3'

c. Write the amino acid sequence if a mutation changes CGG to GGG. Is this likely to affect protein function?

Textbook Question

For each of the following, note whether the component can be found in a virus, a cell, or both.

b. DNA polymerase

Textbook Question

For each of the following, note whether the component can be found in a virus, a cell, or both.

c. capsid

Textbook Question

For each of the following, note whether the component can be found in a virus, a cell, or both.

a. RNA