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In this activity you will learn how to use a computer to analyze related amino acid sequences from a variety of animals to gain insight on their evolutionary ...
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[Written by: Baylee Goodwin, Dane Besser, and Stephen Ramsey] Vocabulary Words Phylogenetics Taxa Node Speciation event Most Recent Common Ancestor (MRCA) Descendants Sister Clades Outgroup Background During the Mass Spectrometry and BLAST activities, you were given amino acid sequences that had been recovered from a fossilized bone specimen from a Tyrannosaurus rex (as well as sequences from a Hadrosaur and a Mastodon). You learned how to input the T. rex amino acid sequence into BLAST to identify what present day animals are most closely related to T. rex. In this activity you will learn how to use a computer to analyze related amino acid sequences from a variety of animals to gain insight on their evolutionary relationships. Phylogenetics is the study of evolutionary relationships among a set of taxa, where taxa is another name for groups of organisms, like plants and animals. In phylogenetics, evolutionary relationships are laid out on a phylogenetic tree (fig 1 &3). The root of the tree is the start of the evolutionary lineage being depicted. As you move from the left to the right, you are moving forward in time. As time passes you can see how nodes diverge in two directions, this is a speciation event. Which is when a group of animals separates and evolves into two brand new groups of animal. The nodes also mark where the most recent common ancestor (MRCA) is. For example, in figure 3, A and B are groups of animals that diverged from a MRCA found at the node that join the two. The leaves at the end of the tree mark the descendants of the ancestors. Phylogenetic trees are a useful way to compare Figure 2: This is an example of DNA sequences from multiple species lined up together. Species who share mutations that others do not have are more closely related. This is how molecular biology can help determine evolutionary relationships. Figure 1 : This is an example of a phylogenetic tree showing how to read it.
how animals are related to one another. In figure 3, animals from group A and B are more closely related to each other than they are to animals in group C. Therefore, A and B would be considered sister clades, since they are the most closely related. Group C would be considered the outgroup since they are the most distantly related. There are two main methods on how to determine the evolution of a set of taxa: morphology vs molecular data. Morphology uses physical features of animals to determine how they evolved, whereas molecular data uses DNA/amino acid sequences to determine where speciation events occurred. Molecular data is typically more accurate since mutations in DNA are the driving force for evolution. When mutations arise in the DNA sequence of an organism, they can result in changes to the translated amino acid sequence of a protein. For example, the original DNA sequence in a small portion of a gene might have read ATAAGT, but after the mutation it reads ATAACT (i.e., a G was replaced with a C). This changes the amino acid in the sequence from leucine to a stop codon (signaling the end of the protein), which results in the cell making a shortened protein whose function may substantially differ from the original full length protein. When a mutation is present in an organism's cell, it can be passed on from the organism to its offspring, which is how animals evolve on a molecular scale. The genetic differences between two species, such as a bird and a lizard, represent the accumulation of billions of mutations over many millions of years. The differences in the DNA (or, as we will study today, protein) sequences among a set of representative species can be used to determine how the species are related. As we will discover, the more closely related organisms will have more similar protein sequences, and the more distantly related organisms will have more dissimilar protein sequences. In order to create a phylogenetic tree, the first step is to obtain protein sequence data from a set of animal species that we want to compare. We will be searching for the "alpha 2 type 1 collagen" protein sequence since that is the what scientists were able to extract from the fossilized femur bone of the T. rex. Collagen is evolutionarily rather well conserved across species, which is why it is a good choice for using amino acid sequences to build a phylogenetic tree. When a protein is “well conserved” it means that the protein is found in multiple species that are distantly related, collagen is a well conserved protein found in all animals with true bone. In order to find the collagen sequence, you will conduct a search in an online database called GenBank. The alpha 2 type 1 collagen protein sequences have already been collected for you for most of the animals, however you still need to collect the appropriate amino acid sequence for the T. rex. Figure 3: This is an example of a basic phylogenetic tree. It highlights where the most recent common ancestors (MRCA) are found on the tree, and which animal groups evolved from the ancestor.
Some things students might find puzzling are: humans evolving before mastodon, even though the mastodon has been extinct for several thousand years;; and the fact that chicken evolved from mammals (the dog and toxodon came before the chicken), implying that the birds evolved from mammals. However, birds evolved long before mammals did. This is due to the very short amino acid sequence that was recovered from the T rex ;; most amino acid sequences are thousands of amino acids long, rather than 18. If a more complete protein was recovered, the tree would be more precise.
Collagen Sequence Data (Copy and past everything below, including the “>”):
Human MLSFVDTRTLLLLAVTLCLATCQSLQEETVRKGPAGDRGPRGERGPPGPPGRDGEDGPTGPPGPPGPPG PPGLGGNFAAQYDGKGVGLGPGPMGLMGPRGPPGAAGAPGPQGFQGPAGEPGEPGQTGPAGARGPA GPPGKAGEDGHPGKPGRPGERGVVGPQGARGFPGTPGLPGFKGIRGHNGLDGLKGQPGAPGVKGEPG APGENGTPGQTGARGLPGERGRVGAPGPAGARGSDGSVGPVGPAGPIGSAGPPGFPGAPGPKGEIGAV GNAGPAGPAGPRGEVGLPGLSGPVGPPGNPGANGLTGAKGAAGLPGVAGAPGLPGPRGIPGPVGAAGA TGARGLVGEPGPAGSKGESGNKGEPGSAGPQGPPGPSGEEGKRGPNGEAGSAGPPGPPGLRGSPGSR GLPGADGRAGVMGPPGSRGASGPAGVRGPNGDAGRPGEPGLMGPRGLPGSPGNIGPAGKEGPVGLPG IDGRPGPIGPAGARGEPGNIGFPGPKGPTGDPGKNGDKGHAGLAGARGAPGPDGNNGAQGPPGPQGV QGGKGEQGPPGPPGFQGLPGPSGPAGEVGKPGERGLHGEFGLPGPAGPRGERGPPGESGAAGPTGPIG SRGPSGPPGPDGNKGEPGVVGAVGTAGPSGPSGLPGERGAAGIPGGKGEKGEPGLRGEIGNPGRDGA RGAPGAVGAPGPAGATGDRGEAGAAGPAGPAGPRGSPGERGEVGPAGPNGFAGPAGAAGQPGAKGE RGAKGPKGENGVVGPTGPVGAAGPAGPNGPPGPAGSRGDGGPPGMTGFPGAAGRTGPPGPSGISGPP GPPGPAGKEGLRGPRGDQGPVGRTGEVGAVGPPGFAGEKGPSGEAGTAGPPGTPGPQGLLGAPGILGL PGSRGERGLPGVAGAVGEPGPLGIAGPPGARGPPGAVGSPGVNGAPGEAGRDGNPGNDGPPGRDGQP GHKGERGYPGNIGPVGAAGAPGPHGPVGPAGKHGNRGETGPSGPVGPAGAVGPRGPSGPQGIRGDKG EPGEKGPRGLPGLKGHNGLQGLPGIAGHHGDQGAPGSVGPAGPRGPAGPSGPAGKDGRTGHPGTVGP AGIRGPQGHQGPAGPPGPPGPPGPPGVSGGGYDFGYDGDFYRADQPRSAPSLRPKDYEVDATLKSLNN QIETLLTPEGSRKNPARTCRDLRLSHPEWSSGYYWIDPNQGCTMDAIKVYCDFSTGETCIRAQPENIPAK NWYRSSKDKKHVWLGETINAGSQFEYNVEGVTSKEMATQLAFMRLLANYASQNITYHCKNSIAYMDEE TGNLKKAVILQGSNDVELVAEGNSRFTYTVLVDGCSKKTNEWGKTIIEYKTNKPSRLPFLDIAPLDIGGA DQEFFVDIGPVCFK Chicken MLSFVDTRILLLLAVTSYLATSQHLFQASAGRKGPRGDKGPQGERGPPGPPGRDGEDGPPGPPGPPGPP
Trout MLSFVDNRILLLLAVTSLLASCQSGGLKGPRGAKGPRGDRGPQGPNGRDGKAGLPGIAGPPGPPGLGG NFAAQFDGGKGSDPGPGPMGLMGSRGPNGPPGAPGPQGFTGHAGEPGEPGQTGSIGARGPTGSAGKP GEDGNNGRPGKPGDRGGPGTQGARGFPGTPGLPGMKGHRGYNGLDGRKGESGTAGAKGETGAHGA
Cattle MLSFVDTRTLLLLAVTSCLATCQSLQEATARKGPSGDRGPRGERGPPGPPGRDGDDGIPGPPGPPGPPG PPGLGGNFAAQFDAKGGGPGPMGLMGPRGPPGASGAPGPQGFQGPPGEPGEPGQTGPAGARGPPGPP GKAGEDGHPGKPGRPGERGVVGPQGARGFPGTPGLPGFKGIRGHNGLDGLKGQPGAPGVKGEPGAPG ENGTPGQTGARGLPGERGRVGAPGPAGARGSDGSVGPVGPAGPIGSAGPPGFPGAPGPKGELGPVGN PGPAGPAGPRGEVGLPGLSGPVGPPGNPGANGLPGAKGAAGLPGVAGAPGLPGPRGIPGPVGAAGATG ARGLVGEPGPAGSKGESGNKGEPGAVGQPGPPGPSGEEGKRGSTGEIGPAGPPGPPGLRGNPGSRGLP GADGRAGVMGPAGSRGATGPAGVRGPNGDSGRPGEPGLMGPRGFPGSPGNIGPAGKEGPVGLPGIDG RPGPIGPAGARGEPGNIGFPGPKGPSGDPGKAGEKGHAGLAGARGAPGPDGNNGAQGPPGLQGVQGG
Frog MLSFVDLRSVLLLAVTLYLVTCQEVRRGPRGDKGPPGEQGPPGIPGRDGEDGLPGLPGPPGVPGLGGNF AAQYDPSKSAEPGQQGIMGPRGPPGPPGSPGSQGFQGLPGENGEPGQTGPVGSRGPSGAPGKAGEDG HPGKSGRPGERGPVGPQGARGFPGTPGLPGFKGIRGHTGSDGQKGAPGAAGVKGENGANGDNGSPG QAGARGLPGERGRIGPAGSAGSRGSDGSSGPVGPAGPIGSAGAPGLPGAPGAKGELGPAGNNGPTGA AGGRGEPGPPGSLGPAGPPGNPGTNGVNGAKGTAGLPGVGGAPGLPGGRGIPGPAGPAGPSGARGLA GDPGIAGGKGDTGSKGEPGSVGQQGPAGPSGEEGKRGPNGEAGSSGPSGNAGIRGVPGTRGLPGPD GRAGGIGPAGSRGSSGPPGARGPNGDAGRPGEPGLLGARGLPGFSGSNGPQGKEGPAGPQGIEGRSG AAGPAGARGEPGAIGFPGPKGPNGEPGKNGDKGNQGPSGNRGAPGPDGNNGAQGPAGLGGATGEKG EQGPSGAPGFQGLPGPGGPPGEVGKPGERGAPGDFGPPGSAGTRGERGAPGESGGAGPHGPSGSRGP SGAPGPDGQKGEPGAAGLNGGLGPSGPAGIPGERGTAGTPGTKGEKGDAGNSGDYGNPGRDGARGP AGAAGAPGPAGGPGDRGESGPAGPSGVAGPRGAPGERGEAGPAGPTGFAGPPGAAGHTGAKGDRGA
Mastodon QYDAKGVGLGPGPMGLMGPRGPPGATGPPGSPGFQGPPGEPGEPGQTGPAGSRGPAGPPGKAGEDGH PGKPGRPGERGVVGPQGARGFPGTPGLPGFKGIRGHNGLDGLKGQPGAPGVKGEPGAPGENGTPGQI GARGLPGERGRVGGPGPAGARGSDGSVGPVGPAGPIGSAGPPGFPGAPGPKGEIGPVGNPGPSGPAGP RGEAGLPGVSGPVGPPGNPGANGLAGAKGAAGLPGVAGAPGLPGPRGIPGPVGAAGATGARGIVGEPG PAGSKGESGSKGEPGSAGPQGPPGPSGEEGKRGPNGEAGSAGPAGPPGLRGGPGSRGLPGADGRAGV MGPPGSRGASGPAGVRGPSGDSGRPGEPGVMGPRGLPGSPGNVGPAGKEGPAGLPGIDGRPGPIGPA GARGEPGNIGFPGPKGPAGDPGKNGDKGHAGLAGPRGAPGPDGNNGAQGPPGLQGVQGGKGEQGPA GPPGFQGLPGPSGTAGEAGKPGERGIPGEFGLPGPAGPRGERGPPGQSGAAGPTGPIGSRGPSGPPGP DGNKGEPGVVGAPGTAGPSGPVGLPGERGAAGIPGGKGEKGETGLRGDTGNTGRDGARGAPGAVGAP GPAGATGDRGEAGPAGSAGPAGPRGSPGERGEVGPAGPNGFAGPAGAAGQAGAKGERGTKGPKGEN GPVGPTGPVGAAGPAGPNGPPGPAGSRGDGGPPGATGFPGAAGRTGPPGPAGITGPPGPPGAAGKEGL RGPRGDQGPVGRTGETGASGPPGFAGEKGSSGEPGTAGPPGAPGPQGILGPPGILGLPGSRGERGLPG VAGAVGEPGPLGIAGPPGARGPPGAVGSPGVNGAPGEAGRDGNPGSDGPPGRDGLPGHKGERGYPGN AGPVGTAGAPGPQGPLGPAGKHGNRGEPGPAGSVGPVGAVGPRGPSGPQGARGDKGEAGDKGPRGL PGFKGHNGLQGLPGLAGQHGDQGSPGSVGPAGPRGPAGPSGPVGKDGRPGHAGAVGPAGVRGSQGS QGPSGPPGPPGPPGPPGPSGGGYDFGYDGDFYRA Salamander MLSFVDTRIVLLLAVTSSLATCQYNYEANRGPRGYKGPQGDQGPPGAPGRDGVDGPPGPAGPPGPPGP SGLGGNFAAQYDGGKSDPGPGPMGMMGPRGPPGPSGSPGAQGFQGLPGEPGEPGQTGPVGSRGPTG PPGKSGEDGSPGKSGRPGERGTVGTQGARGFPGTPGLPGFKGLRGHNGFDGVKGAAGSQGAKGETG ANGENGSPGQAGARGLPGERGRVGGAGPGARGSDGSAGPSGPAGPIGSAGAPGLPGAPGAKGEIGSA GNNGPSGPAGSRGDPGLPGSVGPVGPAGNPGSNGVSGAKGAAGLPGVGGAPGLPGPRGIPGPQGASG AAGARGLAGDPGSPGGKGDSGSKGEPGSAGQQGNAGPSGEEGKRGPNGEPGSSGPAGPAGIRGVPG