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12 which mechanism allows for more than one polypeptide to be encoded by a single gene? Guides
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Gene ⇒ Polypeptide [1]
• The amino acid sequence of polypeptides is coded for by genes. A gene is a sequence of DNA which encodes a polypeptide sequence
– Transcription – making an mRNA transcript based on a DNA template (occurs within the nucleus). – Translation – using the instructions of the mRNA transcript to link amino acids together (occurs at the ribosome)
– Genes may be alternatively spliced to generate multiple polypeptide variants. – Genes encoding tRNA sequences are transcribed but never translated
Gene ⇒ Polypeptide [2]
Bạn đang xem: 12 which mechanism allows for more than one polypeptide to be encoded by a single gene? Guides
• The amino acid sequence of polypeptides is coded for by genes. A gene is a sequence of DNA which encodes a polypeptide sequence
– Transcription – making an mRNA transcript based on a DNA template (occurs within the nucleus). – Translation – using the instructions of the mRNA transcript to link amino acids together (occurs at the ribosome)
– Genes may be alternatively spliced to generate multiple polypeptide variants. – Genes encoding tRNA sequences are transcribed but never translated
One gene many proteins – Higher Biology Unit 1 Revision [3]
(e) Different proteins can be expressed from one gene as a result of alternative RNA splicing and post-translational modification. Different mRNA molecules are produced from the same primary transcript depending on which RNA segments are treated as exons and introns.
source: RNA Splicing: Introns, Exons and Spliceosome By: Suzanne Clancy, Ph.D. It is now becoming clear that the number of genes present in cells is fewer than the number of proteins which those cells can produce
There are two processes which contribute to the production of more than one protein. Post transcriptional processes (alternative RNA splicing) and post translational modification.
Multiple Genes, One Polypeptide Chain [4]
“Two Genes, One Polypeptide Chain–Fact or Fiction” was the title of a major symposium at an American Association of Immunologists meeting in the early 1970s (1). What is impossible for today’s young immunologists to imagine is that for about 20 years (from the discovery of the “Todd Phenomenon”—that rabbit allotypes, which were thought to be encoded by V regions, were shared by at least two if not three Ig classes—about 1963) until the publication of the Early et al
Yet, all immunologists believed that two genes encoded a single Ig: a V gene and a C gene.. In the 1970s, a series of papers were published that began to call into doubt the notion that a single gene encoded a variable region
For entirely different reasons, Tom Kindt and I had come to the conclusion that “there has to be more than a single gene per variable region.” Tom argued that because the rabbit allotypes were located in the “N terminal 100 amino acids” of the H chain, and because the C-terminal part of the rabbit H chain had an amino acid sequence that was quite independent of the N-terminal portion, the best way to explain this was “two genes per variable region.” In a similar vein, data my laboratory had collected taught two things. First, the phylogenetically associated residues (those amino acids at particular positions that distinguished one species from another) were confined to the region “up to position 100 of the heavy chain.” Second, we had found Abs derived from unrelated people to have identical amino acid sequences in the region beyond position 100, but very different before position 100
Alternative splicing [5]
Alternative splicing, or alternative RNA splicing, or differential splicing, is an alternative splicing process during gene expression that allows a single gene to code for multiple proteins. In this process, particular exons of a gene may be included within or excluded from the final, processed messenger RNA (mRNA) produced from that gene.[1] This means the exons are joined in different combinations, leading to different (alternative) mRNA strands
Biologically relevant alternative splicing occurs as a normal phenomenon in eukaryotes, where it increases the number of proteins that can be encoded by the genome.[1] In humans, it is widely believed that ~95% of multi-exonic genes are alternatively spliced to produce functional alternative products from the same gene[2] but many scientists believe that most of the observed splice variants are due to splicing errors and the actual number of biologically relevant alternatively spliced genes is much lower.[3][4]. Alternative splicing enables the regulated generation of multiple mRNA and protein products from a single gene.[5]
In this mode, a particular exon may be included in mRNAs under some conditions or in particular tissues, and omitted from the mRNA in others.[1]. The production of alternatively spliced mRNAs is regulated by a system of trans-acting proteins that bind to cis-acting sites on the primary transcript itself
Part Three: Gene Expression and Protein Synthesis [6]
Once transcription and processing of rRNAs, tRNAs and snRNAs are completed, the RNAs are ready to be used in the cell ‑ assembled into ribosomes or snRNPs and used in splicing and protein synthesis. But the mature mRNA is not yet functional to the cell
Experiments testing the effects of frameshift mutations showed that the deletion or addition of 1 or 2 nucleotides caused a loss of function, whereas deletion or addition of 3 nucleotides allowed retention of considerable function. This demonstrated that the coding unit is 3 nucleotides
Each group of three nucleotides encodes one amino acid. Since there are 64 combinations of 4 nucleotides taken three at a time and only 20 amino acids, the code is degenerate (more than one codon per amino acid, in most cases)
Alternative Splicing Tutorial [7]
References >> Gene SplicingGene Splicing Overview & Techniques. Gene splicing is a post-transcriptional modification in which a single gene can code for multiple proteins
Gene splicing is an important source of protein diversity. During a typical gene splicing event, the pre-mRNA transcribed from one gene can lead to different mature mRNA molecules that generate multiple functional proteins
Gene splicing is observed in high proportion of genes. In human cells, about 40-60% of the genes are known to exhibit alternative splicing.
Genetic Code and Translation – Introduction to Molecular Biology [8]
Within this chapter, we will cover the details of prokaryotic and eukaryotic translation. Translation is the process of converting the information housed in mRNA into the protein sequence
Amino acids are linearly strung together via covalent bonds (called peptide bonds) between amino and carboxyl termini of adjacent amino acids. The sequential polymerization of amino acids, in a strict order determined by the sequence of an mRNA, is catalyzed by a ribonucleoprotein complex called the ribosome working with decoding “keys” termed charged tRNAs.
Due to this compartmentalization, transcription and translation are separated spatially and temporally within the cell. Transcription occurs within the nucleus of eukaryotes and translation occurs within the cytoplasm (Fig
6.4: Protein Synthesis [9]
Your DNA, or deoxyribonucleic acid, contains the genes that determine who you are. How can this organic molecule control your characteristics? DNA contains instructions for all the proteins your body makes
What determines a protein’s structure? It begins with the sequence of amino acids that make up the protein. Instructions for making proteins with the correct sequence of amino acids are encoded in DNA.
How do the instructions in DNA get to the site of protein synthesis outside the nucleus? Another type of nucleic acid is responsible. RNA is a small molecule that can squeeze through pores in the nuclear membrane
SOLVED: Which mechanism allows genes for more than one polypeptide to be encoded by a single? self-splicing of introns regulated transcription RNA methylation alternative intron splicing RNA interfere [10]
Get 5 free video unlocks on our app with code GOMOBILE. Which mechanism allows genes for more than one polypeptide to be encoded by a single?
Alternative splicing of an eukaryotic gene can occur if:- There is at least one intron.- There is more than one consensus sequence where the spliceosome can cut.- There are more than two spliceosomes available.- There are multiple transcription factors affecting intron splicing.. Question 74 (1.5 points) Alternative splicing refers to:the use of alternative ‘reading frames when translating a mRNA splicing out of damaged DNA by DNA repair enzymes joining of RNA from two different genes to form a new mRNA the use of different exons as introns during RNA processingQuestion 75 (1.5 points) A man was born with six fingers on each hand and six toes on each foot: His wife and their son have a normal number of digits
Their mating demonstrates which kind of experiment?testcrosssuppressive crossredundant crossreciprocal crossdihybrid cross. Question 722 ptsIn forming proteins: mRNA carries the tRNA carries the tRNA temporarily bonds to mRNA in a ribosome; where formation of proteins occurs This relationship between a nucleotide codon and its corresponding amino acid is called theamino acids (and anticodons); codons; genetic codeall of the thesecodons; amino acids (and anticodons); genetic codenone of theseligase; promoter region; Okazaki fragment
How do genes direct the production of proteins?: MedlinePlus Genetics [11]
Most genes contain the information needed to make functional molecules called proteins. (A few genes produce regulatory molecules that help the cell assemble proteins.) The journey from gene to protein is complex and tightly controlled within each cell
Together, transcription and translation are known as gene expression.. During the process of transcription, the information stored in a gene’s DNA is passed to a similar molecule called RNA (ribonucleic acid) in the cell nucleus
The type of RNA that contains the information for making a protein is called messenger RNA (mRNA) because it carries the information, or message, from the DNA out of the nucleus into the cytoplasm.. Translation, the second step in getting from a gene to a protein, takes place in the cytoplasm
What is a gene, post-ENCODE? History and updated definition [12]
What is a gene, post-ENCODE? History and updated definition. – 1 Program in Computational Biology & Bioinformatics, Yale University, New Haven, Connecticut 06511, USA;
– 3 Computer Science Department, Yale University, New Haven, Connecticut 06511, USA;. – 4 Center for Medical Informatics, Yale University, New Haven, Connecticut 06511, USA;
– 6 Stockholm Bioinformatics Center, Albanova University Center, Stockholm University, SE-10691 Stockholm, Sweden;. – 7 Genetics Department, Yale University, New Haven, Connecticut 06511, USA;
Sources
- http://ib.bioninja.com.au/standard-level/topic-2-molecular-biology/24-proteins/gene–polypeptide.html#:~:text=Genes%20may%20be%20alternatively%20spliced,produce%20an%20alternative%20polypeptide%20sequence
- http://ib.bioninja.com.au/standard-level/topic-2-molecular-biology/24-proteins/gene–polypeptide.html
- https://blogs.glowscotland.org.uk/gc/hyndsecbiohu1/one-gene-many-proteins/
- https://journals.aai.org/jimmunol/article/173/11/6501/2103/Multiple-Genes-One-Polypeptide-Chain
- https://en.wikipedia.org/wiki/Alternative_splicing
- https://www.bx.psu.edu/~ross/workmg/GeneticCodeCh13.htm
- http://www.premierbiosoft.com/tech_notes/gene-splicing.html
- https://iu.pressbooks.pub/iul211smehta/chapter/genetic-code-and-translation/
- https://bio.libretexts.org/Bookshelves/Human_Biology/Human_Biology_(Wakim_and_Grewal)/06%3A_DNA_and_Protein_Synthesis/6.04%3A_Protein_Synthesis
- https://www.numerade.com/ask/question/0-question-27-2pts-which-mechanism-allows-gene-for-more-than-one-polypeptide-to-be-encoded-by-a-single-self-splicing-of-introns-regulated-transcription-rna-methylation-alternative-intron-spl-79938/
- https://medlineplus.gov/genetics/understanding/howgeneswork/makingprotein/
- https://genome.cshlp.org/content/17/6/669.full
