Skip to main content
Pearson+ LogoPearson+ Logo
Ch. 21 - Genomic Analysis
All textbooksKlug 12th EditionCh. 21 - Genomic AnalysisProblem 22
Previous problem
Next problem
Chapter 20, Problem 22

Homology can be defined as the presence of common structures because of shared ancestry. Homology can involve genes, proteins, or anatomical structures. As a result of 'descent with modification,' many homologous structures have adapted different purposes. Is it likely that homologous proteins from different species have the same or similar functions? Explain.

Verified step by step guidance
1
Understand the concept of homology: Homology refers to similarities due to shared ancestry. In genetics, homologous proteins are those that have evolved from a common ancestral protein.
Consider the evolutionary process: During evolution, proteins can undergo changes or modifications that allow them to adapt to different functions or environments, a process known as 'descent with modification'.
Analyze the function of homologous proteins: While homologous proteins may have originated from a common ancestor, they can evolve to perform different functions in different species. However, they may also retain similar functions if the evolutionary pressures and environmental conditions are similar.
Evaluate the likelihood of similar functions: If the homologous proteins are under similar selective pressures or are involved in fundamental biological processes, it is likely that they will retain similar functions across different species.
Conclude with an explanation: Homologous proteins from different species may have similar functions if they are involved in essential biological processes or if the selective pressures have not significantly altered their function. However, they can also diverge to perform different roles if the evolutionary context demands it.

Verified Solution

Video duration:
2m
This video solution was recommended by our tutors as helpful for the problem above.
Was this helpful?

Key Concepts

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

Homology

Homology refers to the similarity in structure or function between different species due to shared ancestry. This concept can apply to various biological levels, including genes, proteins, and anatomical features. Understanding homology is crucial for studying evolutionary relationships and how traits have been modified over time.
Recommended video:
Guided course
03:51
Recombination after Single Strand Breaks

Descent with Modification

Descent with modification is a key principle of evolution, suggesting that species evolve over time through changes in their traits. This process leads to the diversification of species from common ancestors, resulting in homologous structures that may serve different functions in different environments. It highlights how evolutionary pressures shape the adaptations of organisms.
Recommended video:
Guided course
04:30
Post Translational Modifications

Protein Function and Evolution

Proteins are essential molecules that perform a variety of functions in living organisms, and their functions can evolve over time. While homologous proteins may share structural similarities due to common ancestry, their functions can diverge significantly due to different evolutionary pressures and environmental contexts. This means that homologous proteins from different species may not necessarily have the same or similar functions.
Recommended video:
Guided course
08:22
Evolution
Previous problem
Next problem
Related Practice
Textbook Question
In Section 21.10 we briefly discussed the Human Proteome Map (HPM). An interactive Web site for the HPM is available at http://www.humanproteomemap.org. Visit this site, and then answer the questions in parts (a) and (b) and complete part (c). 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.
333
views
Textbook Question
Researchers have compared candidate loci in humans and rats in search of loci in the human genome that are likely to contribute to the constellation of factors leading to hypertension [Stoll, M., et al. (2000). Genome Res. 10:473–482]. Through this research, they identified 26 chromosomal regions that they consider likely to contain hypertension genes. How can comparative genomics aid in the identification of genes responsible for such a complex human disease? The researchers state that comparisons of rat and human candidate loci to those in the mouse may help validate their studies. Why might this be so?
289
views
Textbook Question
Homology can be defined as the presence of common structures because of shared ancestry. Homology can involve genes, proteins, or anatomical structures. As a result of 'descent with modification,' many homologous structures have adapted different purposes. List three anatomical structures in vertebrates that are homologous but have different functions.
403
views
Textbook Question
Homology can be defined as the presence of common structures because of shared ancestry. Homology can involve genes, proteins, or anatomical structures. As a result of 'descent with modification,' many homologous structures have adapted different purposes. Under what circumstances might one expect proteins of similar function to not share homology? Would you expect such proteins to be homologous at the level of DNA sequences?
232
views
Textbook Question

Yeager, M., et al. [(2007) Nature Genetics 39:645–649] and Sladek, R., et al. [(2007) Nature 445:881–885] have used single-nucleotide polymorphisms (SNPs) in genome-wide association studies (GWAS) to identify novel risk loci for prostate cancer and Type 2 diabetes, respectively. Each study suggests that disease-risk genes can be identified that significantly contribute to the disease state. Given your understanding of such complex diseases, what would you determine as reasonable factors to consider when interpreting the results of GWAS?

246
views
Textbook Question
Comparisons between human and chimpanzee genomes indicate that a gene that may function as a wild-type or normal gene in one primate may function as a disease-causing gene in another [The Chimpanzee Sequencing and Analysis Consortium (2005). Nature 437:69–87]. For instance, the PPARG locus (regulator of adipocyte differentiation) is a wild-type allele in chimps but is clearly associated with Type 2 diabetes in humans. What factors might cause this apparent contradiction? Would you consider such apparent contradictions to be rare or common? What impact might such findings have on the use of comparative genomics to identify and design therapies for disease-causing genes in humans?
493
views