Hich One of the Following Amino Acids Sequences Did You Build in the Active Art?

NOVA scienceNOW: Bird Brains

Classroom Activity

Activeness Summary
Students volition compare the sequence of amino acids in a gene shared between humans and half dozen other organisms and infer evolutionary relationships among the species.

Learning Objectives
Students will be able to:

• explain that different organisms often have the same genes.

• understand how scientists use genetic differences to infer evolutionary relationships.

• relate how shared genes may be a upshot of shared evolutionary history.

• provide testify suggesting that living things share common ancestors.

Suggested Fourth dimension
1 class period

• Predicting Evolutionary Relationships Student Handout (PDF)

Groundwork
In the NOVA scienceNOW segment Bird Brains, students acquire that organisms as various as mushrooms, fish, flies, and humans share a gene called FOXP2. This gene produces a type of poly peptide called a transcription factor, which turns other genes "on" or "off." Transcription factors regulate many other genes, and because of this, they may affect multiple processes in unlike organisms. In animals, the FOXP2 gene is especially active during embryonic development in the brain, gut, eye, and lungs, simply scientists are still unraveling which genes it regulates in each of these tissues.

As explained in the NOVA scienceNOW segment, FOXP2 too plays a office in the processes involved in human being oral communication and birdsong: people with an altered form of the gene accept difficulty with many aspects of speech, and birds whose FOXP2 activeness is disrupted accept trouble learning songs. Despite these and other observations, scientists however don't know which other genes FOXP2 regulates or what its function is in the numerous other species that share this gene with birds and humans. That FOXP2 is so widespread raises additional questions, not merely about its part in other organisms, but also how the gene differs from one organism to the adjacent.

All life on Earth arose from a single common ancestor, and our genes reflect this shared ancestry. As species differentiated over evolutionary fourth dimension, the DNA sequences in their genes acquired slight changes. According to evolutionary theory, these changes accrue over fourth dimension: species that diverged from each other long agone accept more than differences in their Dna than species that diverged recently. Scientists utilise this caste of difference as a molecular clock to help them predict how long ago species carve up apart from i another. In general, scientists say the longer ago two species dissever, the more distantly related they are.

You may demand to remind your students about the nature of Deoxyribonucleic acid, genes, proteins, and amino acids and how they differ from one some other. Deoxyribonucleic acid is a molecule made up of iv types of units called bases. The 4 bases—adenine (A), cytosine (C), guanine (G) and thymine (T)—collectively make upwardly the DNA "alphabet." Genes are singled-out locations along the length of a DNA molecule. The sequence of bases in a gene determines the lodge of amino acids in a protein, and the lodge of amino acids acts as the blueprint for protein assembly.

Considering the DNA sequence determines a protein'due south amino acid sequence, a cistron shared by two closely related organisms should take similar, or even identical, amino acid sequences. That'due south considering closely related species nigh likely diverged from one another adequately recently in the evolutionary bridge. Thus, they oasis't had every bit much time to accumulate random mutations in their genetic codes.

For years, scientists take used DNA and amino acid sequences to decipher relationships between closely related species, such as different types of reptiles, birds, and even leaner. The approach, called "molecular phylogeny," compares sequence information and ranks organisms' degree of relatedness based on the differences in their DNA. As researchers sequence the genomes of an increasing number of organisms every yr, they uncover more data to utilize in evolutionary studies. In the emerging field of phylogenomics, researchers simultaneously compare numerous genes—and will one day compare complete genomes—to build new evolutionary copse.

In this activity, your students will clarify a suite of amino acid sequences from a gene that makes the protein Cytochrome C. All eukaryotic organisms share this poly peptide, which plays a central office in the energy-producing process of cellular respiration. Cytochrome C is an atomic number 26-containing molecule that carries electrons during the electron send concatenation in cellular respiration. The poly peptide is found in many lineages, including those of animals, plants, and numerous unicellular species. Its ubiquity makes it a convenient tool for studying evolution. By counting the number of amino acid differences between humans and vi other species, your students will be able to brand predictions about how closely related humans are to each species.

Before the Lesson

• Bookmark the Web sites Bird Brains and Biological science: Molecular Differences.
• Prepare enough copies of the Predicting Evolutionary Relationships student handout so that each student will have one.
• Equally a grade, watch the NOVA scienceNOW segment Bird Brains.
• If necessary, review the terms "DNA," "amino acid," "cistron," and "protein" with the grade.

The Lesson

1. Lead a short begin session about how scientists classify organisms. What criteria might scientists use to determine how closely related two species are? They might expect for similarity in physical features, behavior, manner of reproduction, or genes.
2. Innovate the concept of using molecular bear witness, such as Deoxyribonucleic acid or amino acrid sequence data, to unravel evolutionary relationships betwixt species (see background). Yous might point out that for some species, concrete traits alone don't offer enough clues. For example, is a equus caballus more closely related to a dog or to a buffalo? All three accept fur and walk on four legs, but these clues don't tell you lot much about evolution. Optional: If possible, show the brusk animation Biology: Molecular Differences. Ask students what additional data Dna evidence provides scientists studying evolution.
3. Dissever the class into pairs and distribute the Predicting Evolutionary Relationships handout.
4. Work through an example as a class.
   • Explicate that each alphabetic character in the table Amino Acids in the Protein Cytochrome C represents an amino acid in the protein Cytochrome C. The key shows them which amino acrid corresponds to each letter.
   • Call students' attention to the amino acrid sequences for humans and tuna. Be sure students sympathize that because the sequence is as well long to fit on i line of text, it wraps to a second line. Explicate that they volition look for the number of amino acids that differ between humans and tuna. Likewise explicate that evidently-text letters correspond amino acids that may vary betwixt species, while messages in bold are amino acids that are identical in all species.
   • First, count the number of differences in the sequence together. The first difference is at position 17; humans take an "I," while tuna have a "T." Be sure all students tin can identify the 21 differences between humans and tuna.
5. Have students consummate the handouts.
6. To wrap up, hash out the following points as a class:
   • The tabular array lists three species of fungi: Candida, Neurospora, and bakery's yeast. How similar are their Cytochrome C sequences? Their sequences are quite different, with 41 differences betwixt neurospora and baker'due south yeast, 43 betwixt neurospora and Candida, and 27 betwixt baker's yeast and Candida. What can you lot say nigh the evolutionary relationships amidst the fungi compared to the relationship between the two insects on the table, the screwworm fly and the silkworm moth? The wing and the moth are more than closely related in evolutionary time; at that place are but 14 differences between the fly and moth Cytochrome C sequences.
   • Pigs, cows, and sheep have identical Cytochrome C sequences. How can they have the same sequence but be different species? The departure between species is determined by many factors; different species can notwithstanding take identical sequences, especially if they diverged from a common ancestor recently in evolutionary time.
   • Is it appropriate for scientists to infer evolutionary relationships based on information from only one protein? Why or why not? These animals each have thousands of genes. The fact that one gene is identical for the 3 animals says nothing about the other genes. It's better to look at multiple proteins or other sources of DNA show. Proteins evolve at different rates, and additional pieces of evidence will make a prediction about an evolutionary human relationship stronger.

Extension

Divide the class into four teams. Assign each team one of the following genes: FOXP2, hemoglobin blastoff, eyeless, and sonic hedgehog. Have students visit the Kyoto Encyclopedia of Genes and Genomes and look up their cistron's amino acid sequence in humans. Have students research how many of the six species from their handouts share this gene with humans; for all cases in which species share the gene, have students write downwardly the offset ten amino acids listed in the database. Then have students prepare a brusque study about the cistron, how much similarity they discovered between humans and other species, and what scientists know virtually the gene's office.

Assessment
Activity answers:
Human being-tuna: ____21___
Human: gray whale ___9____
Human: snapping turtle: ____15___
Human-rhesus monkey: ___1__
Homo: chicken/turkey: ___13____
Human: neurospora (a type of bread mold): __51_______

Educatee Handout Questions

1. Based on the amino acrid sequence data you nerveless, which organism are humans well-nigh closely related to? Which organisms are humans virtually distantly related to? Explain your reasoning.
   Humans are most closely related to the monkey; there is only i amino acrid departure between the two. Humans are most distantly related to Neurospora; in that location are 51 amino acid differences between the two.
2. What additional data or data might help you confirm the statement you made above?
   Information from other genes would strengthen the argument; we also could use fossil evidence or physical show such as similarity in physical structures and features.
3. Does your answer to Question 1 to a higher place match the prediction you made in Step two of the Procedure? Explain your answer.
   Answers will vary; expect for show that students compare their answers and explain why they are the same, or why they are different.
4. Explain how amino acid sequence data tin help scientists infer patterns of evolutionary relationships between species.
   An amino acid is one of the building blocks of a protein. A cistron's Dna sequence determines the club of amino acids that make upward a poly peptide, so changes in the DNA sequence oft result in changes in the amino acid sequence equally well. By looking for amino acid sequence differences betwixt species, scientists can infer how closely or distantly related two species are in evolutionary time.

Use the post-obit rubric to assess each team's work.

	Splendid	Satisfactory	Needs comeback
Completing handouts and participating in discussion	Students clearly empathise how molecular evidence relates to inferring patterns of development Students ask follow-upwards questions showing creativity and disquisitional thinking	Students miscount amino acrid difference between species and practice not make a connection between molecular prove and patterns of evolution	Students make little effort to consummate handouts or participate in give-and-take.

The "Bird Brains" activity aligns with the following National Science Pedagogy Standards (encounter books.nap.edu/html/nses).

Grades 9-12
Content Standard C
Life Science

• Molecular footing of heredity

Content Standard F
Science in Personal and Social Perspectives

• Personal and Community Health

Classroom Activity Author

Jennifer Cutraro and WGBH Educational Outreach Staff

Jennifer Cutraro has 12 years of experience in scientific discipline writing and education. She has written text and ancillaries for Houghton Mifflin, K¹², and Delta Teaching and has taught science and environmental education at science centers beyond the country. She likewise contributes news and characteristic stories about science and health to media outlets including The Los Angeles Times, The Boston Globe, Science News for Kids and Scholastic Science World.

Funding for NOVA scienceNOW is provided past Pfizer, the National Science Foundation, the Howard Hughes Medical Institute, the Alfred P. Sloan Foundation, and public idiot box viewers.

A private corporation funded by the American people

This material is based upon piece of work supported by the National Scientific discipline Foundation under Grant no. 0638931. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necssarily reflect the views of the National Science Foundation.

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Source: https://www.pbs.org/wgbh/nova/teachers/activities/0304_01_nsn.html