Worksheet
Creating Phylogenetic Trees
from DNA Sequences
Student Handout
CREATINGPHYLOGENETICTREESFROMDNASEQUENCES
INTRODUCTION
ThisworksheetcomplementstheClickandLearn“CreatingPhylogeneticTreesfromDNASequences”developed
inconjunctionwiththe2011HolidayLecturesonScience,“Bones,Stones,andGenes:TheOriginofModern
Human.”
PROCEDURE
Answerthefollowingquestionsasyouproceedthroughtheactivityslides.
1.Brieflyexplainhowscientistsdrawrelationshipsbetweenorganismsbasedonsharedanatomicalfeatures.
2.HowareDNAsequencesusedtodeduceevolutionaryrelationships?
3.WhatisoneadvantageofbuildingphylogenetictreesusingDNAcomparisonsratherthananatomical
features?
4.Watchthevideocliponslide3andthendrawasimpletreeillustratingtheevolutionaryrelationships
betweengorillas,chimpanzees,humans,andorangutans.
5.Watchtheshortvideoonslide4.Howhasbiotechnologyaffectedtheprocessofbuildingphylogenetictrees
fromDNAsequences?
www.BioInteractive.org
PublishedDecember2014
RevisedFebruary2017
Page1of5
Worksheet
Creating Phylogenetic Trees
from DNA Sequences
Student Handout
6.Whatdoevolutionarilyrelatedorganismsshare?
7.Whataretwocommontypesofmutations?
8.Watchtheshortanimationonslide6anddescribeaSNP.
9.Watchtheshortanimationonslide7anddescribeanindel.
10.ExplainthedifferencebetweendistantlyrelatedandcloselyrelatedorganismsintermsoftheirDNA
sequences.
11.Whatdoesitmeantocompare“applestoapples”whenreferringtoDNAsequencesfromdifferent
organisms?
12.Watchtheshortanimationonslide10andexplainwhatismeantby“aligning”DNAsequences.
13.HowisaSNPidentifiedinanalignment?
14.Howisanindelidentifiedinanalignment?
www.BioInteractive.org
PublishedDecember2014
RevisedFebruary2017
Page2of5
Worksheet
Creating Phylogenetic Trees
from DNA Sequences
Student Handout
15.Lookattheinformationonslide15.Fromlefttoright,identifythebaseineachboxasanindeloraSNP.
Writeyouranswersinthespacesbelow.
Box1(left)
Box2(center)
Box3(right)
NowclickoneachboxandcheckyouranswerstoQuestion15above.
16.Watchthevideocliponslide17.Howcanyouidentifythetwosequencesthataremostsimilar?
17.Watchthevideocliponslide18anddescribethelinkbetweenthelengthofthelineandtime.
18.Whatissurprisingabouttheplacementofhipposonthephylogenetictree?
19.Defineabranchpoint(alsocalledanode)onaphylogenetictreeanddescribewhatitrepresents.
20.Whatistheroot?
21.Whatdoesthenodeclosesttotherootrepresent?
22.Describewhatanunrootedphylogenetictreerepresents.
23.Onslides22and23,noticehowphylogenetictreescanrotatearoundnodesandhavedifferentshapes.
Noticetherelationshipsbetweentheorganismsdonotchange.
24.Usingtheinformationonslide24,explainhowDNAevidencesupportstheknownbiologyofthesevencone
snails.
www.BioInteractive.org
PublishedDecember2014
RevisedFebruary2017
Page3of5
Worksheet
Creating Phylogenetic Trees
from DNA Sequences
Student Handout
25. WritethreeconclusionsdrawnfromtheinformationprovidedinthisClickandLearn.
a.
b.
c.
www.BioInteractive.org
PublishedDecember2014
RevisedFebruary2017
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Worksheet
Creating Phylogenetic Trees
from DNA Sequences
Student Worksheet
EXTENSIONACTIVITY
Addressthefollowingconceptsinessayforminthespaceprovidedbelow.
Phylogenyistheevolutionaryhistoryofaspecies:
a. Theevolutionofaspeciesisdependentonchangesinthegenomeofthespecies.Identifytwomechanismsof
geneticchange,andexplainhoweachaffectsgeneticvariation.
b. Describetwotypesofevidence–otherthanthecomparisonofDNAsequences–thatcanbeusedtodetermine
thephylogenyoforganisms.Discussonestrengthofeachtypeofevidenceyoudescribed.
www.BioInteractive.org
PublishedDecember2014
RevisedFebruary2017
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