Ch. 18 - Genomics, Bioinformatics, and Proteomics

Klug - Essentials of Genetics 10th Edition

Klug10th EditionEssentials of GeneticsISBN: 9780135588789Non è quello che usi tu?Cambia libro di testo

Klug 10th Edition

Ch. 18 - Genomics, Bioinformatics, and Proteomics

Problema 19

Capitolo 18, Problema 19

Annotation of the human genome sequence reveals a discrepancy between the number of protein-coding genes and the number of predicted proteins actually expressed by the genome. Proteomic analysis indicates that human cells are capable of synthesizing more than 100,000 different proteins and perhaps three times this number. What is the discrepancy, and how can it be reconciled?

Guida verificata passo dopo passo

Step 1: Understand the discrepancy by recognizing that the human genome contains approximately 20,000-25,000 protein-coding genes, but proteomic analyses detect over 100,000 different proteins, indicating more proteins than genes.

Step 2: Explore the concept of alternative splicing, where a single gene can produce multiple mRNA variants by including or excluding certain exons, leading to different protein isoforms from the same gene.

Step 3: Consider post-translational modifications (PTMs), such as phosphorylation, glycosylation, and ubiquitination, which chemically modify proteins after translation and increase protein diversity without changes in the gene sequence.

Step 4: Recognize other mechanisms contributing to protein diversity, including RNA editing, use of alternative promoters, and alternative translation start sites, all of which can generate multiple protein products from a single gene.

Step 5: Conclude that the discrepancy arises because the number of protein-coding genes does not directly equate to the number of distinct proteins expressed; instead, multiple molecular processes expand the proteome complexity beyond the gene count.

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Gene Number vs. Protein Diversity

The human genome contains approximately 20,000 protein-coding genes, but the number of distinct proteins expressed is much higher. This discrepancy arises because a single gene can give rise to multiple protein products, meaning gene count alone does not directly reflect protein diversity.

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Percorso guidato

05:05

Proteins

Alternative Splicing

Alternative splicing is a process where different combinations of exons are joined from a single pre-mRNA transcript, producing multiple mRNA variants. This mechanism allows one gene to encode several distinct proteins, significantly increasing proteomic complexity beyond the gene count.

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Percorso guidato

01:57

Alternative DNA Forms

Post-Translational Modifications

After translation, proteins can undergo chemical modifications such as phosphorylation, glycosylation, or ubiquitination. These post-translational modifications alter protein function and structure, further expanding the diversity of proteins derived from the genome.

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04:30

Post Translational Modifications

Pratica correlata

Domanda del libro di testo

An interactive Web site for the Human Proteome Map (HPM) is available at http://www.humanproteomemap.org. Visit this site, and then answer the question.

Use the 'Query' tab and select the 'Gene family' dropdown menu to do a search on the distribution of proteins encoded by a pathway of interest to you. Search in fetal tissues, adult tissues, or both.

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What are DNA microarrays? How are they used?

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Metagenomics studies generate very large amounts of sequence data. Provide examples of genetic insight that can be learned from metagenomics.

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It can be said that modern biology is experiencing an 'omics' revolution. What does this mean? Explain your answer.

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An interactive Web site for the Human Proteome Map (HPM) is available at http://www.humanproteomemap.org. Visit this site, and then answer the question.

How many fetal tissues were analyzed?

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Domanda del libro di testo

An interactive Web site for the Human Proteome Map (HPM) is available at http://www.humanproteomemap.org. Visit this site, and then answer the question.

How many proteins were identified in this project?

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