Concept explainers
Some proteins are composed of two or more polypeptides. Suppose the DNA template strand sequence
What is the amino acid sequence of the polypeptideproduced from this sequence?
What term is used to identify a functional protein like this one formed when two identical polypeptides jointogether?
To analyze:
Few proteins are composed of two or more polypeptides. Assume the DNA template strand sequence 3’-TACGTAGGCTAACGGAGTAAGCTAACT-5’ yields a polypeptide that joins in sets to form a functional protein.
From this sequence, the amino acid sequence of the polypeptide produced is to be explained.
Name the term used to identify a functional protein which is produced from the joining of two identical polypeptides.
Introduction:
In molecular biology, the central dogma describes the formation of a polypeptide chain from the template DNA strand through the intermediate formation of mRNA.
Transcription Translation
DNA → mRNA → polypeptide
The DNA contains the information for the given polypeptide in the form of specific sequences of codons. The codon is a triplet of nitrogen bases coding the specific amino acid. There are 64 codons which code 20 different types of amino acids. These amino acids are bounded together by a peptide bond to form polypeptide. The number of polypeptides bounded together form the protein molecule.
Amino acid → polypeptide → Protein molecule
Explanation of Solution
The DNA template will undergo the following process to form the polypeptide chain:
3’ TACGTAGGCTAACGGAGTAAGCTAACT5’ DNA template
↓ Transcription
5’AUGCAUCCGAUUGCCUCAUUCGAUUGA3 mRNA
↓ Translation
N-Met-His-Pro-Ileu-Ala-Ser-Phe-Asp-Stop-C Polypeptide chain
Functional proteins are made up of two or more polypeptide chains which may be same or different to each other. As the two polypeptides chains are identical in nature, they will join together to form a homodimer.
The amino acid sequence of a polypeptide chain is determined by the sequence of codons present on the DNA template strand.
The term “homodimer” is used when two identical polypeptide chains are bounded together.
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Chapter 9 Solutions
Genetic Analysis: An Integrated Approach (3rd Edition)
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