1. Which Of The Following Does Not Contribute To Evidence That Animals Share A Common Ancestor?

NOVA scienceNOW: Bird Brains

Classroom Activity

Activity Summary
Students will compare the sequence of amino acids in a gene shared between humans and 6 other organisms and infer evolutionary relationships among the species.

Learning Objectives
Students will be able to:

• explicate that different organisms oftentimes have the same genes.

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

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

• provide evidence suggesting that living things share mutual ancestors.

Suggested Time
Ane class menstruum

• Predicting Evolutionary Relationships Educatee Handout (PDF)

Background
In the NOVA scienceNOW segment Bird Brains, students learn that organisms every bit diverse equally mushrooms, fish, flies, and humans share a gene called FOXP2. This factor produces a blazon of protein 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 dissimilar organisms. In animals, the FOXP2 factor is especially active during embryonic development in the encephalon, gut, heart, and lungs, only scientists are even so unraveling which genes it regulates in each of these tissues.

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

All life on Earth arose from a unmarried mutual antecedent, and our genes reverberate this shared beginnings. Equally species differentiated over evolutionary time, the Deoxyribonucleic acid sequences in their genes acquired slight changes. According to evolutionary theory, these changes accumulate over fourth dimension: species that diverged from each other long ago accept more differences in their DNA than species that diverged recently. Scientists use this degree of divergence as a molecular clock to help them predict how long ago species split autonomously from one another. In full general, scientists say the longer ago two species carve up, the more distantly related they are.

You lot may need to remind your students about the nature of Deoxyribonucleic acid, genes, proteins, and amino acids and how they differ from 1 some other. Dna is a molecule fabricated up of four types of units called bases. The four bases—adenine (A), cytosine (C), guanine (G) and thymine (T)—collectively make upwardly the Deoxyribonucleic acid "alphabet." Genes are singled-out locations along the length of a Deoxyribonucleic acid molecule. The sequence of bases in a gene determines the order of amino acids in a protein, and the guild of amino acids acts every bit the design for poly peptide assembly.

Considering the DNA sequence determines a protein's amino acrid sequence, a gene shared by ii closely related organisms should accept similar, or fifty-fifty identical, amino acid sequences. That's because closely related species well-nigh likely diverged from one another fairly recently in the evolutionary bridge. Thus, they oasis't had as much fourth dimension to accumulate random mutations in their genetic codes.

For years, scientists have used DNA and amino acrid sequences to decipher relationships betwixt closely related species, such as different types of reptiles, birds, and even bacteria. 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 than information to use in evolutionary studies. In the emerging field of phylogenomics, researchers simultaneously compare numerous genes—and volition 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 poly peptide Cytochrome C. All eukaryotic organisms share this protein, which plays a central role in the free energy-producing process of cellular respiration. Cytochrome C is an iron-containing molecule that carries electrons during the electron transport chain in cellular respiration. The poly peptide is constitute in many lineages, including those of animals, plants, and numerous unicellular species. Its ubiquity makes information technology a convenient tool for studying evolution. By counting the number of amino acid differences between humans and six other species, your students will be able to make predictions near how closely related humans are to each species.

Before the Lesson

• Bookmark the Spider web sites Bird Brains and Biology: Molecular Differences.
• Prepare plenty copies of the Predicting Evolutionary Relationships student handout then that each student will have one.
• Equally a class, watch the NOVA scienceNOW segment Bird Brains.
• If necessary, review the terms "Dna," "amino acrid," "gene," and "poly peptide" with the grade.

The Lesson

1. Atomic number 82 a short brainstorm session about how scientists classify organisms. What criteria might scientists use to determine how closely related two species are? They might await for similarity in physical features, behavior, way of reproduction, or genes.
2. Introduce the concept of using molecular bear witness, such as Deoxyribonucleic acid or amino acid sequence data, to unravel evolutionary relationships between species (see background). You might indicate out that for some species, physical traits lonely don't offering enough clues. For example, is a horse more closely related to a dog or to a buffalo? All three have fur and walk on four legs, but these clues don't tell y'all much well-nigh evolution. Optional: If possible, show the short animation Biology: Molecular Differences. Inquire students what additional information Deoxyribonucleic acid evidence provides scientists studying evolution.
3. Split the class into pairs and distribute the Predicting Evolutionary Relationships handout.
4. Piece of work through an example equally a class.
   • Explain that each letter in the table Amino Acids in the Protein Cytochrome C represents an amino acrid in the poly peptide 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 certain students understand that because the sequence is too long to fit on one line of text, it wraps to a second line. Explain that they volition wait for the number of amino acids that differ between humans and tuna. Likewise explain that plainly-text letters stand for amino acids that may vary between species, while messages in bold are amino acids that are identical in all species.
   • Showtime, count the number of differences in the sequence together. The offset divergence is at position 17; humans take an "I," while tuna accept a "T." Exist sure all students tin can identify the 21 differences betwixt humans and tuna.
5. Have students complete the handouts.
6. To wrap up, talk over the following points as a course:
   • The table lists three species of fungi: Candida, Neurospora, and baker'southward yeast. How similar are their Cytochrome C sequences? Their sequences are quite different, with 41 differences betwixt neurospora and baker's yeast, 43 betwixt neurospora and Candida, and 27 between baker's yeast and Candida. What can you say near the evolutionary relationships among the fungi compared to the relationship between the ii insects on the tabular array, the screwworm fly and the silkworm moth? The fly and the moth are more closely related in evolutionary time; there are only 14 differences between the fly and moth Cytochrome C sequences.
   • Pigs, cows, and sheep accept identical Cytochrome C sequences. How tin can they take the same sequence merely be dissimilar species? The difference betwixt species is determined by many factors; different species can still have identical sequences, especially if they diverged from a common ancestor recently in evolutionary fourth dimension.
   • Is it appropriate for scientists to infer evolutionary relationships based on data from only one protein? Why or why not? These animals each take thousands of genes. The fact that one gene is identical for the three animals says nothing about the other genes. Information technology's better to look at multiple proteins or other sources of DNA evidence. Proteins evolve at unlike rates, and boosted pieces of evidence will make a prediction most an evolutionary human relationship stronger.

Extension

Dissever the class into iv teams. Assign each team one of the following genes: FOXP2, hemoglobin alpha, eyeless, and sonic hedgehog. Have students visit the Kyoto Encyclopedia of Genes and Genomes and look up their gene'south amino acid sequence in humans. Have students research how many of the vi species from their handouts share this gene with humans; for all cases in which species share the factor, have students write down the first ten amino acids listed in the database. And then take students prepare a short report about the cistron, how much similarity they discovered between humans and other species, and what scientists know about the cistron's part.

ASSESSMENT
Activity answers:
Human-tuna: ____21___
Human being: grey whale ___9____
Human: snapping turtle: ____15___
Human-rhesus monkey: ___1__
Human: craven/turkey: ___13____
Human: neurospora (a blazon of bread mold): __51_______

Student Handout Questions

1. Based on the amino acrid sequence data you collected, which organism are humans well-nigh closely related to? Which organisms are humans well-nigh distantly related to? Explicate your reasoning.
   Humans are about closely related to the monkey; there is only one amino acrid difference between the two. Humans are most distantly related to Neurospora; there are 51 amino acrid differences between the two.
2. What additional data or information might assistance you confirm the statement yous made above?
   Information from other genes would strengthen the statement; we besides could utilize fossil evidence or physical evidence such equally similarity in physical structures and features.
3. Does your reply to Question 1 to a higher place match the prediction you lot made in Step 2 of the Procedure? Explain your respond.
   Answers volition vary; await for show that students compare their answers and explain why they are the same, or why they are different.
4. Explicate how amino acid sequence data can help scientists infer patterns of evolutionary relationships betwixt species.
   An amino acid is one of the edifice blocks of a protein. A cistron'southward Dna sequence determines the order of amino acids that brand up a protein, so changes in the Dna sequence often upshot in changes in the amino acid sequence equally well. By looking for amino acrid sequence differences between species, scientists can infer how closely or distantly related ii species are in evolutionary time.

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

	Excellent	Satisfactory	Needs improvement
Completing handouts and participating in give-and-take	Students clearly understand how molecular evidence relates to inferring patterns of development Students inquire follow-upwardly questions showing creativity and disquisitional thinking	Students miscount amino acrid departure betwixt species and do non make a connectedness between molecular show and patterns of evolution	Students make little endeavour to consummate handouts or participate in word.

The "Bird Brains" activity aligns with the following National Scientific discipline Education Standards (see books.nap.edu/html/nses).

Grades nine-12
Content Standard C
Life Science

• Molecular basis of heredity

Content Standard F
Science in Personal and Social Perspectives

• Personal and Customs Wellness

Classroom Activity Author

Jennifer Cutraro and WGBH Educational Outreach Staff

Jennifer Cutraro has 12 years of experience in science writing and educational activity. She has written text and ancillaries for Houghton Mifflin, K¹², and Delta Education and has taught science and environmental educational activity at science centers across the land. She too contributes news and characteristic stories about science and wellness to media outlets including The Los Angeles Times, The Boston Globe, Science News for Kids and Scholastic Scientific discipline Earth.

Funding for NOVA scienceNOW is provided past Pfizer, the National Scientific discipline Foundation, the Howard Hughes Medical Institute, the Alfred P. Sloan Foundation, and public television viewers.

A private corporation funded past the American people

This material is based upon piece of work supported by the National Science Foundation nether Grant no. 0638931. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do non necssarily reflect the views of the National Scientific discipline Foundation.

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

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