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data-pid="1160" title="Mark as favorite" onclick="return false;"><i class="fa fa-star-o"></i></a> </h1> <ol class="breadcrumb"> <li><a href="../../../biology.html"><i class="fa fa-home"></i></a><i class="fa fa-fw fa-chevron-right divider"></i></li><li><a href="../469/07-nucleic-acids-ahl.html">07 Nucleic acids AHL</a><i class="fa fa-fw fa-chevron-right divider"></i></li><li><span class="gray">Nucleic acids 7.1 HL</span></li> <span class="pull-right" style="color: #555" title="Suggested study time: 30 minutes"><i class="fa fa-clock-o"></i> 30'</span> </ol> <article id="main-article"> <style type="text/css">ol.breadcrumb { margin-bottom: 0 }</style><div id="toc-1675505968" class="toc"><a href="#" class="toc-switcher" title="Show table of contents"><small><i class="fa fa-reorder"></i> Table of contents <span class="pull-right"><i class="fa fa-chevron-down"></i></span></small></a><ol><li><a href="#header-1" class="scroll-to" data-target="header-1">Summary list for topic 7.1 DNA structure and replication.</a></li><li><a href="#header-2" class="scroll-to" data-target="header-2">Model answer</a></li><li><a href="#header-3" class="scroll-to" data-target="header-3">Answers to the quick questions</a></li><li><a href="#header-4" class="scroll-to" data-target="header-4">Model answer:</a></li><li><a href="#header-5" class="scroll-to" data-target="header-5">Model answer</a></li><li><a href="#header-6" class="scroll-to" data-target="header-6">Model answer</a><ol></ol></li><li><a href="#header-7" class="scroll-to" data-target="header-7"> 7.1 DNA structure and replication 1/1 </a></li></ol><li><a href="#header-8" class="scroll-to" data-target="header-8">Drag and drop activities</a></li></div><div class="intro-card" readonly="false"><img alt="" src="../../images/07_nucleic_acids/simple-dna-replication.jpeg" style="float: left; width: 148px; height: 100px;">The basics of DNA structure and DNA replication were covered in the SL topic so this topic looks at some extra details including, the 3' and 5' ends of the two antiparallel strands and further details about the enzymes responsible for DNA replication and some of the DNA regions which don't code for proteins but that regulate gene expression, form introns, telomeres or genes for tRNA. To understand how modern sequencing machines work a clear understanding of PCR and gel electrophoresis is also required.</div> <div class="panel panel-turquoise"> <div class="panel-heading"><a class="expander pull-right" href="#"><span class="fa fa-plus"></span></a> <div> <p>Key concepts</p> </div> </div> <div class="panel-body"> <div> <p>Learn and test your biological vocabulary for 7.1 Nucleic acids using these flashcards.</p> <p style="text-align: center"><iframe height="500" src="https://quizlet.com/8332107/flashcards/embed?i=xxmo&x=1jj1" style="border:0" width="100%"></iframe></p> </div> </div> <div class="panel-footer"> <div> <p>text</p> </div> </div> </div> <div class="panel panel-default"> <div class="panel-footer"> <div> <p>text</p> </div> </div> </div> <div class="panel panel-yellow"> <div class="panel-heading"><a class="expander pull-right" href="#"><span class="fa fa-plus"></span></a> <div> <p>Essentials</p> </div> </div> <div class="panel-body"> <div> <p>These slides summarise the essential understanding and skills in this topic. <br> They contain short explanations in text and images - good revision for all students.</p> <p>Read the slides and look up any words or details you find difficult to understand.</p> <div id="carousel-155" class="dynamic-gallery carousel slide" data-id="155"><div class="carousel-inner" role="listbox"><div class="item active"><a class="fancy" href="../../../std-galleries/5-155/img0.jpg" data-fancybox="gallery-155" title="" data-caption=""><img alt="" src="../../../std-galleries/5-155/img0.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-155/img1.jpg" data-fancybox="gallery-155" title="" data-caption=""><img alt="" src="../../../std-galleries/5-155/img1.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-155/img2.jpg" data-fancybox="gallery-155" title="" data-caption=""><img alt="" src="../../../std-galleries/5-155/img2.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-155/img3.jpg" data-fancybox="gallery-155" title="" data-caption=""><img alt="" src="../../../std-galleries/5-155/img3.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-155/img4.jpg" data-fancybox="gallery-155" title="" data-caption=""><img alt="" src="../../../std-galleries/5-155/img4.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-155/img5.jpg" data-fancybox="gallery-155" title="" data-caption=""><img alt="" src="../../../std-galleries/5-155/img5.jpg"></a></div></div><a class="left carousel-control" href="#carousel-155" role="button" data-slide="prev"><i class="fa fa-fw fa-chevron-left"></i></a><a class="right carousel-control" href="#carousel-155" role="button" data-slide="next"><i class="fa fa-fw fa-chevron-right"></i></a></div><ol class="std-carousel-indicators"><li data-index="0"><img title="Click to view" src="../../../std-galleries/5-155/img0-thumb128.jpg"><li><li data-index="1"><img title="Click to view" src="../../../std-galleries/5-155/img1-thumb128.jpg"><li><li data-index="2"><img title="Click to view" src="../../../std-galleries/5-155/img2-thumb128.jpg"><li><li data-index="3"><img title="Click to view" src="../../../std-galleries/5-155/img3-thumb128.jpg"><li><li data-index="4"><img title="Click to view" src="../../../std-galleries/5-155/img4-thumb128.jpg"><li><li data-index="5"><img title="Click to view" src="../../../std-galleries/5-155/img5-thumb128.jpg"><li></li></ol> </div> </div> <div class="panel-footer"> <div> <p>These slides summarise the essential understanding and skills in this topic. <br> They contain short explanations in text and images - great revision.</p> <p>Read the slides and look up any words or details you find difficult to understand.</p> <div id="carousel-210" class="dynamic-gallery carousel slide" data-id="210"><div class="carousel-inner" role="listbox"><div class="item active"><a class="fancy" href="../../../std-galleries/5-210/112movement-1.jpg" data-fancybox="gallery-210" title="" data-caption=""><img alt="" src="../../../std-galleries/5-210/112movement-1.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-210/112movement-2.jpg" data-fancybox="gallery-210" title="" data-caption=""><img alt="" src="../../../std-galleries/5-210/112movement-2.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-210/112movement-3.jpg" data-fancybox="gallery-210" title="" data-caption=""><img alt="" src="../../../std-galleries/5-210/112movement-3.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-210/112movement-4.jpg" data-fancybox="gallery-210" title="" data-caption=""><img alt="" src="../../../std-galleries/5-210/112movement-4.jpg"></a></div><div class="item "><a class="fancy" href="../../../std-galleries/5-210/112movement-5.jpg" data-fancybox="gallery-210" title="" data-caption=""><img alt="" src="../../../std-galleries/5-210/112movement-5.jpg"></a></div></div><a class="left carousel-control" href="#carousel-210" role="button" data-slide="prev"><i class="fa fa-fw fa-chevron-left"></i></a><a class="right carousel-control" href="#carousel-210" role="button" data-slide="next"><i class="fa fa-fw fa-chevron-right"></i></a></div><ol class="std-carousel-indicators"><li data-index="0"><img title="Click to view" src="../../../std-galleries/5-210/112movement-1-thumb128.jpg"><li><li data-index="1"><img title="Click to view" src="../../../std-galleries/5-210/112movement-2-thumb128.jpg"><li><li data-index="2"><img title="Click to view" src="../../../std-galleries/5-210/112movement-3-thumb128.jpg"><li><li data-index="3"><img title="Click to view" src="../../../std-galleries/5-210/112movement-4-thumb128.jpg"><li><li data-index="4"><img title="Click to view" src="../../../std-galleries/5-210/112movement-5-thumb128.jpg"><li></li></ol> </div> </div> </div> <div class="panel panel-violet"> <div class="panel-heading"><a class="expander pull-right" href="#"><span class="fa fa-plus"></span></a> <div> <p>Summary</p> </div> </div> <div class="panel-body"> <div> <h3 id="header-1">Summary list for topic 7.1 DNA structure and replication.<small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505968" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h3> <p><u>DNA structure</u></p> <ul> <li class="liWithoutP">Part of DNA supercoiling are structures called Nucleosomes.</li> <li class="liWithoutP">DNA structure gives a clue to the mechanism of DNA replication.</li> <li class="liWithoutP">Non-coding regions of DNA have other important functions, limited to regulators of gene expression, introns, telomeres and genes for tRNAs.</li> </ul> <p><u>DNA replication (in prokaryotes only)</u></p> <ul> <li class="liWithoutP">DNA polymerase enzymes can only add nucleotides to the 3’ end of a primer.</li> <li class="liWithoutP">Continuous DNA replication occurs on the leading strand and discontinuous on the lagging strand.</li> <li class="liWithoutP">A complex group of enzymes do DNA replication including; helicase, DNA gyrase, single strand binding proteins, DNA primase and DNA polymerases I and III.</li> </ul> <p><u>Crossing over</u></p> <ul> <li>DNA replication makes a second chromatid in each chromosome in interphase before meiosis.</li> <li>Crossing over exchanges pieces of DNA between non-sister homologous chromatids and forms new combinations of alleles on the chromosomes formed in meiosis.</li> </ul> <div class="yellowBg"> <p class="liWithoutP"><u>Skills</u> (can you ...)</p> <div class="yellowBg"> <ul> <li class="liWithoutP">See that Rosalind Franklin’s and Maurice Wilkins’ X-ray diffraction work gave evidence for helix and two strands in DNA structure.</li> <li class="liWithoutP">Awareness that the <a href="http://www.dnalc.org/resources/animations/sangerseq.html" target="_blank">Sanger method of base sequencing</a> uses nucleotides containing dideoxyribonucleic acid (DNA with deoxyribose missing 2 oxygen molecules) to stop DNA replication at a specific base which allows sequencing using fluorescent markers and computers. (Sanger chain termination. Video <a href="http://dnalc.org/view/15479-Sanger-method-of-DNA-sequencing-3D-animation-with-narration.html" target="_blank">here).</a></li> <li class="liWithoutP">Awareness that in DNA profiling <a href="http://dnalc.org/view/15102-Using-tandem-repeats-for-DNA-fingerprinting-Alec-Jeffreys.html" target="_blank">Tandem repeats</a> are used as these vary greatly from person to person.</li> <li class="liWithoutP">Ability to analyse of results of the<a href="../../../olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120076/bio21.swf::Hershey%20and%20Chase%20Experiment" target="_blank"> Hershey and Chase experiment</a> providing evidence that DNA is the genetic material.<a href="http://www.accessexcellence.org/RC/VL/GG/hershey.php" target="_blank">(This is a nice graphic).</a></li> <li class="liWithoutP">Analyse of molecular visualisations of the association between protein and DNA in a nucleosome.</li> </ul> </div> </div> </div> </div> <div class="panel-footer"> <div> <p>text</p> </div> </div> </div> <div class="panel panel-default"> <div class="panel-heading"><a class="expander pull-right" href="#"><span class="fa fa-plus"></span></a> <div> <p>Exam style questions</p> </div> </div> <div class="panel-body"> <div> <p>To prepare to answer a difficult IB question about DNA replication it is useful to break down the task into smaller steps.<br> Here is an example.</p> <div class="yellowBg"> <p><strong>Describe the process of DNA replication (8 marks)</strong></p> <p>Step 1: From your revision notes you might be able to list structures and enzymes that are important.</p> <p>E.g.</p> <ol> <li>Helicase</li> <li>Single strand binding proteins</li> <li>Primase</li> <li>DNA polymerase III</li> <li>Leading strand</li> <li>Lagging strand</li> <li>Okazaki fragments</li> <li>DNA polymerase I</li> <li>DNA ligase</li> </ol> <p>Step 2: Create a quick question for each of these things.<br> Step 3: Practise remembering the answers to these short questions.</p> </div> <p>Click the + icon to see a model answer.</p> <button class="btn btn-xs bg-turquoise showhider"><i class="fa fa-fw fa-plus"></i></button><section class="hiddenbox hidden"> <h3 id="header-2">Model answer<small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505968" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h3> <div class="yellowBg"> <p>Quick questions for each of the points.<br> Test yourself. How many answers do you know.</p> <p>1. What does helicase do?<br> 2. Which proteins keep the DNA strands separate?<br> 3. What is the role of the enzyme primase?<br> 4. How is DNA polymerase III different from primase?<br> 5. Which direction does DNA polymerase III travel along the template stand in the leading strand?<br> 6. What is the lagging strand?<br> 7. Why are okazaki fragments produced on the lagging strand?<br> 8. What is the role of the enzyme DNA polymerase I ?<br> 9. What is the role of DNA ligase enzyme?</p> </div> <h3 id="header-3">Answers to the quick questions<small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505968" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h3> <div class="blueBg"> <p>1. What does helicase do?</p> <p style="margin-left: 40px;"><span style="color:#FF0000;">Separates the two DNA strands by breaking hydrogen bonds.</span></p> <p>2. Which proteins keep the DNA strands separate?</p> <p style="margin-left: 40px;"><span style="color:#FF0000;">Single strand binding proteins.</span></p> <p>3. What is the role of the enzyme primase?</p> <p style="margin-left: 40px;"><span style="color:#FF0000;">Primase attaches an RNA primer to the DNA strand.</span></p> <p>4. How is DNA polymerase III different from primase?</p> <p style="margin-left: 40px;"><span style="color:#FF0000;">DNA polymerase III adds DNA nucleotides, Primase adds RNA nucleotides to the strand.</span></p> <p>5. Which direction does DNA polymerase III travel along the template stand in the leading strand?</p> <p style="margin-left: 40px;"><span style="color:#FF0000;">From the 3' to the 5' end</span></p> <p>6. What is the lagging strand?</p> <p style="margin-left: 40px;"><span style="color:#FF0000;">The strand on which DNA polymerase III can only work in short sections.</span></p> <p>7. Why are okazaki fragments produced on the lagging strand?</p> <p style="margin-left: 40px;"><span style="color:#FF0000;">DNA polymerase III cannot produce a new strand continuously.</span></p> <p>8. What is the role of the enzyme DNA polymerase I ?</p> <p style="margin-left: 40px;"><span style="color:#FF0000;">DNA polymerase I replace the RNA nucleotides of the primer with DNA nucleotides.</span></p> <p>9. What is the role of DNA ligase enzyme?</p> <p style="margin-left: 40px;"><span style="color:#FF0000;">DNA ligase joins okazaki fragments together.</span></p> </div> </section> <div class="panel panel-has-colored-body panel-expandable panel-has-border panel-default"> <div class="panel-heading"><a class="expander pull-right" href="#"><span class="fa fa-plus"></span></a> <div> <p>Extra exam question on DNA replication. Click to open.</p> </div> </div> <div class="panel-body"> <div> <p>This question requires understanding of DNA Polymerase III function, primase function and DNA structure.</p> <p>Write your answer on paper and then compare it to the model answer.</p> <div class="yellowBg"> <p><b><span calibri="" style="font-size:11.0pt;line-height:107%; font-family:">Explain why DNA replication forms a leading strand and a lagging strand when replicating DNA.<br> (6 marks) </span></b></p> <hr> <hr> <hr> <hr> <hr> <hr> <p><em>Examiner hint: The command term "Explain" asks for reasons to be given for events. Like cause and effect.<br> These points must be linked to the question so in this questions it relates to the function of DNA polymerase III and the direction of its activity in DNA replication</em></p> </div> <p>Click the + icon to see a model answer.</p> <button class="btn btn-xs bg-turquoise showhider"><i class="fa fa-fw fa-plus"></i></button><section class="hiddenbox hidden"> <h3 id="header-4">Model answer:<small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505968" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h3> <div class="yellowBg"> <p><b><span calibri="" style="font-size:11.0pt;line-height:107%; font-family:">Explain why DNA replication forms a leading strand and a lagging strand when replicating DNA. (6 marks) </span></b></p> <ul> <li><span style="color:#FF0000;">DNA polymerase III joins complimentary DNA nucleotides to each of the template strands.</span></li> <li><span style="color:#FF0000;">Enzymes are substrate specific and can only catalyse a reaction when the substrate can bind with the active site.</span></li> <li><span style="color:#FF0000;">DNA Polymerase III can only bind first DNA nucleotide to the 3’ OH group of an RNA primer.</span></li> <li><span style="color:#FF0000;">DNA polymerase III can also bind the 5' phosphate of a new DNA nucleotide to existing DNA nucleotides on the growing strand.</span></li> <li><span style="color:#FF0000;">DNA polymerase therefore builds the new strand from the 5’ of the new strand to the 3’ of the new strand.</span></li> <li><span style="color:#FF0000;">On the leading strand this can happen continuously because 5' to 3' is towards helicase enzyme.</span></li> <li><span style="color:#FF0000;">On the lagging strand this process happens in separate sections, discontinuously, forming Okazaki fragments.</span></li> <li><span style="color:#FF0000;">5' to 3' addition of DNA nucleotides on the lagging strand needs many RNA primers to be added to the strand by Primase enzymes.</span></li> </ul> <p><em>This question is about the leading and lagging strand and the response must be specific.</em></p> </div> </section> </div> </div> </div> <div class="panel panel-has-colored-body panel-expandable panel-has-border panel-default"> <div class="panel-heading"> <div> <p>Extra exam question on non-coding DNA Click to open.</p> </div> </div> <div class="panel-body"> <div> <p>Non-coding DNA was once known as "junk DNA" and it was thought that it didn't have a role in cell function.<br> Later investigations demonstrated that it does has a functional role in the cell.</p> <p align="center">Answer the question below, on a piece of paper, then check your answer against the model answer below.</p> <div class="yellowBg"> <p><strong>Outline the role of non-coding DNA in cell function. (4 marks)</strong></p> <hr> <hr> <hr> <hr> <p><em>Examiner hint: Outline the role - state it function using precise biological terms and give brief details of causes, effects, consequences etc.</em></p> </div> Click on the "+" icon to see a model answer. <button class="btn btn-xs bg-turquoise showhider"><i class="fa fa-fw fa-plus"></i></button><section class="hiddenbox hidden"> <h3 id="header-5">Model answer<small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505968" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h3> <div class="yellowBg"> <p><strong>Outline the role of non-coding DNA in cell function. (4 marks)</strong></p> <p>Name the type of non-coding DNA and then outline the role in cell function.</p> <ul> <li><span style="color:#FF0000;">Telomeres are found at the end of chromosomes.</span></li> <li><span style="color:#FF0000;">Telomeres protect the chromosome from damage during replication.</span></li> <li><span style="color:#FF0000;">Genes which are transcribed to form transfer RNA.</span></li> <li><span style="color:#FF0000;">tRNA is involved in translation of the mRNA base sequence into an amino acid sequence.</span></li> <li><span style="color:#FF0000;">Regulators of gene expression.</span></li> <li><span style="color:#FF0000;">Promoters and silencers control the production of mRNA/transcription.</span></li> </ul> <p><em>Introns have no known function and therefore do not gain credit as the question is about the role of non-coding DNA.</em></p> </div> </section> </div> </div> </div> <div class="panel panel-has-colored-body panel-expandable panel-has-border panel-default"> <div class="panel-heading"> <div> <p>Extra exam question on the structure of a nucleosome Click to open.</p> </div> </div> <div class="panel-body"> <div> <p>DNA is coiled into nucleosomes to be more stable and then supercoiled to form chromosomes for nuclear division.</p> <p>Answer the question below on paper and compare your answer to the model answer.</p> <p><strong>DNA in eukaryotes is associated with proteins to form nucleosomes. Outline the structure of a nucleosome. (3 marks)</strong></p> <div class="yellowBg"> <hr> <hr> <hr> <hr><em>Hint: You could use a simple annotated diagram to answer this question.</em></div> Click on the "+" icon to see a model answer. <button class="btn btn-xs bg-turquoise showhider"><i class="fa fa-fw fa-plus"></i></button><section class="hiddenbox hidden"> <h3 id="header-6">Model answer<small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505968" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h3> <div class="yellowBg"> <p><strong>DNA in eukaryotes is associated with proteins to form nucleosomes. Outline the structure of a nucleosome. (3 marks)</strong></p> <p>An annotated diagram could be done to get these marks. Annotations are brief expalantions included next to the labels.</p> <ul> <li><span style="color:#FF0000;">A nucleosome consists of eight histone proteins and DNA.</span></li> <li><span style="color:#FF0000;">The histone proteins form a core and the DNA is wrapped around the core.</span></li> <li><span style="color:#FF0000;">The DNA is coiled twice around the core.</span></li> <li><span style="color:#FF0000;">The H1 histone is outside the nucleosome.</span></li> <li><span style="color:#FF0000;">The H1 histone locks the DNA in place in the nucleosome.</span></li> </ul> <p><img alt="" src="../../images/richard/7.1-histone.jpg-2.jpg" style="width: 309px; height: 231px;"></p> <p>The diagram does not need to be artistic but reasonably accurate, two dimensional and clearly labelled and annotated. If you annotate the diagram, you do not need to repeat the point in the prose part of your response.</p> </div> </section> </div> </div> </div> </div> </div> <div class="panel panel-green"> <div class="panel-heading"> <div> <p>Test yourself</p> </div> </div> <div class="panel-body"> <div> <p>This quiz contains multiple choice questions covering the understandings and skills in this topic.</p> <br><a class="btn btn-primary btn-block text-center" data-toggle="modal" href="#fe07c343"><i class="fa fa-play"></i> START QUIZ!</a><div class="modal fade modal-slide-quiz" id="fe07c343"> <div class="modal-dialog" style="width: 95vw; max-width: 960px"> <div class="modal-content"> <div class="modal-header slide-quiz-title"> <h4 id="header-7"> 7.1 DNA structure and replication <strong class="q-number pull-right"> <span class="counter">1</span>/<span class="total">1</span> </strong> <small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505968" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h4> </div> <div class="modal-body p-xs-3"> <div class="slide-quiz" data-stats="5-389-1160" style="opacity: 0"> <div class="exercise shadow-bottom"><div class="q-question"><p>It is estimated that a large percentage of human DNA is 'non-coding'.</p><p>Which of the following answers lists important functions of these non-coding regions?</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> Recessive alleles and genes for tRNA molecules</label></p><p><label class="radio"><input class="c" type="radio"> Introns and telomeres</label></p><p><label class="radio"><input type="radio"> Regulators of gene expression, and genes for DNA replication enzymes</label></p><p><label class="radio"><input type="radio"> Exons and genes for tRNA molecules</label></p></div><div class="q-explanation"><p>Non-coding regions of DNA have other important functions, limited to regulators of gene expression, introns, telomeres and genes for tRNAs.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>Which of the following is a role of nucleosomes in eukaryotes?</p></div><div class="q-answer"><p><label class="radio"><input class="c" type="radio"> Part of supercoiling of DNA.</label></p><p><label class="radio"><input type="radio"> Initiation of translation.</label></p><p><label class="radio"><input type="radio"> Protection of mRNA </label></p><p><label class="radio"><input type="radio"> DNA replication</label></p></div><div class="q-explanation"><p>Supercoiling of DNA involves many steps, but the formation of nucleosomes is an impotant part of this. DNA is wrapped two times around a group of histone proteins.<br>Also: Transcription is partly regulated by Nucleosomes in eukaryotes.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>To which part of an RNA primer can DNA polymerase III enzymes add nucleotides?</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> The base</label></p><p><label class="radio"><input type="radio"> The 5' end</label></p><p><label class="radio"><input class="c" type="radio"> The 3' end</label></p><p><label class="radio"><input type="radio"> The phosphate</label></p></div><div class="q-explanation"><p class="liWithoutP">DNA polymerase enzymes can only add nucleotides to the 3’ end of a primer.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>This diagram shows a simplified diagram of DNA replication.</p><p><img alt="" src="../../images/07_nucleic_acids/dna-replication-skeleton-diag.jpeg" style="width: 330px; height: 192px;"></p><p>Which statement best describes what is shown by the diagram?</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> Replication is in a 5' to 3' direction on the leading strand but the opposite on the lagging strand.</label></p><p><label class="radio"><input type="radio"> Replication is faster on the lagging strand that the leading strand.</label></p><p><label class="radio"><input class="c" type="radio"> Replication is continuous on the leading strand and disconinuous on the lagging strand.</label></p><p><label class="radio"><input type="radio"> Replication happens in the same way on both leading and lagging strands.</label></p></div><div class="q-explanation"><p class="liWithoutP">Continuous DNA replication occurs on the leading strand and discontinuous on the lagging strand.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>Which of the following statements give a logical order in the action of just three of the enzymes of the complex group of enzymes which carry out DNA replication?</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> DNA polymerase III, DNA gyrase, DNA polymerase I</label></p><p><label class="radio"><input type="radio"> Helicase, DNA polymerase I, DNA polymerase III</label></p><p><label class="radio"><input class="c" type="radio"> Helicase, DNA primase, DNA polymerase III</label></p><p><label class="radio"><input type="radio"> DNA polymerase I, DNA Gyrase, DNA primase</label></p></div><div class="q-explanation"><p>A complex group of enzymes do DNA replication including; helicase, DNA gyrase, single strand binding proteins, DNA primase and DNA polymerases I and III. (also DNA ligase)</p><p>DNA gyrase and helicase uncoil and unzip the DNA strand, so that DNA primase can attach a primer.<br>Then DNA poymerase III adds DNA nucleotides to the 3' end of the primer. The RNA nucleotides of the primer are replaced by DNA nucleotides by DNA polymerase I.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>Which is the best description of 'crossing-over'</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> The exchange of pieces of DNA between sister chromatids of homologous chromosomes</label></p><p><label class="radio"><input type="radio"> The exchange of pieces of DNA between sister chromatids of autosomes</label></p><p><label class="radio"><input class="c" type="radio"> The exchange of pieces of DNA between non-sister chromatids of homologous chromosomes.</label></p><p><label class="radio"><input type="radio"> The exchange of pieces of DNA between non-sister chromatids of sex chromosomes.</label></p></div><div class="q-explanation"><p>DNA replication makes a second chromatid in each chromosome in interphase before meiosis.</p><p>Crossing over exchanges pieces of DNA between non-sister homologous chromatids and forms new combinations of alleles on the chromosomes formed in meiosis.</p><ul></ul><ul></ul><ul></ul></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="exercise shadow-bottom"><div class="q-question"><p>The diagram shows two bacteriophage virus particles used in a famous experiment by Hershey and Chase.</p><p><img alt="" src="../../images/07_nucleic_acids/bacteriophage.jpeg" style="width: 330px; height: 148px;"></p><p>Why did they use labelled DNA in one and labelled protein in another?</p></div><div class="q-answer"><p><label class="radio"><input type="radio"> They were looking for evidence of crossing over in DNA.</label></p><p><label class="radio"><input type="radio"> They wanted to identify the enzymes and nucleotides in DNA replication.</label></p><p><label class="radio"><input class="c" type="radio"> They wanted to find out whether protein or DNA was inherited by offspring.</label></p><p><label class="radio"><input type="radio"> They wanted to see which molecule entered the host bacteria's cells.</label></p></div><div class="q-explanation"><p>The Hershey and Chase experiment provided evidence that DNA is the genetic material.</p><p>In their experiments they showed that the radioactive label was passed to the DNA in the next generation of bacteriophages.</p></div><div class="slide-q-actions"><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div> </div> </div> <div class="modal-footer slide-quiz-actions"> <div class=""> <div class="pull-left pull-xs-none mb-xs-3"> <button class="btn btn-default d-xs-none btn-prev"> <i class="fa fa-arrow-left"></i> Prev </button> </div> <div class="pull-right pull-xs-none"> <button class="btn btn-success btn-xs-block text-xs-center btn-results" style="display: none"> <i class="fa fa-bar-chart"></i> Check Results </button> <button class="btn btn-default d-xs-none btn-next"> Next <i class="fa fa-arrow-right"></i> </button> <button class="btn btn-default btn-xs-block text-xs-center btn-close" data-dismiss="modal" style="display: none"> Close </button> </div> </div> </div> </div> </div></div> </div> </div> <div class="panel-footer"> <div> <p>text</p> </div> </div> </div> <h3 id="header-8">Drag and drop activities<small class="toc-back-button"><a href="#" class="scroll-to" data-target="toc-1675505968" title="Back to table of contents"><i class="fa fa-chevron-circle-up gray"></i></a></small></h3> <p>Test your ability to construct biological explanations using the drag and drop questions below.</p> <div class="tib-quiz" data-stats="5-900-1160"><p>Structure function relationships are an important Biological concept.</p><p>Drag and drop the correct word or phrase into the gap to outline how the structure of DNA is related to its function.</p><div class="label label-default q-number">1</div><div class="exercise shadow-bottom"><div class="q-question"><p> </p><p class="gap-drop"> <span class="q-text-draggable draggable" draggable="true">double</span> <span class="q-text-draggable draggable" draggable="true">base sequence</span> <span class="q-text-draggable draggable" draggable="true">C-G</span> <span class="q-text-draggable draggable" draggable="true">three</span> <span class="q-text-draggable draggable" draggable="true">one</span> <span class="q-text-draggable draggable" draggable="true">C-T</span> <span class="q-text-draggable draggable" draggable="true">20 </span> <span class="q-text-draggable draggable" draggable="true">replication</span> <span class="q-text-draggable draggable" draggable="true">A-T </span> <span class="q-text-draggable draggable" draggable="true">transcribed</span> <span class="q-text-draggable draggable" draggable="true">A-U</span> <span class="q-text-draggable draggable" draggable="true">complimentary</span> <span class="q-text-draggable draggable" draggable="true">protein manufacture</span> <span class="q-text-draggable draggable" draggable="true">monomers</span> <span class="q-text-draggable draggable" draggable="true">covalent</span> <span class="q-text-draggable draggable" draggable="true">errors</span> <span class="q-text-draggable draggable" draggable="true">two</span> <span class="q-text-draggable draggable" draggable="true">Nucleoside</span> </p></div><div class="q-answer"><p>DNA is ideally suited to accurate <input type="text" style="height: auto;" data-c="replication"> <span class="review"></span> and storage of information for <input type="text" style="height: auto;" data-c="protein manufacture"> <span class="review"></span> .</p><p>The backbone has strong <input type="text" style="height: auto;" data-c="covalent"> <span class="review"></span> bonds giving stability to the DNA molecule.</p><p>The base pairs are contained within the <input type="text" style="height: auto;" data-c="double"> <span class="review"></span> helix. The base pairs bond due to being <input type="text" style="height: auto;" data-c="complimentary"> <span class="review"></span> pairs ( <input type="text" style="height: auto;" data-c="A-T "> <span class="review"></span> and <input type="text" style="height: auto;" data-c="C-G"> <span class="review"></span> ) of equal length and also due the hydrogen bonding between the bases ( three bonds between C-G and <input type="text" style="height: auto;" data-c="two"> <span class="review"></span> bonds between A-T).</p><p>Complimentary base pairing also ensures that DNA is replicated with a minimum chance of <input type="text" style="height: auto;" data-c="errors"> <span class="review"></span> in replication.</p><p> <input type="text" style="height: auto;" data-c="Nucleoside"> <span class="review"></span> triphosphate <input type="text" style="height: auto;" data-c="monomers"> <span class="review"></span> for DNA replication have the energy to bond in order to build a strand of DNA.</p><p>Information for protein manufacture is stored in the <input type="text" style="height: auto;" data-c="base sequence"> <span class="review"></span> which can be <input type="text" style="height: auto;" data-c="transcribed"> <span class="review"></span> into mRNA.</p><p>The information for protein manufacture is stored in units of <input type="text" style="height: auto;" data-c="three"> <span class="review"></span> bases, sufficient to code for <input type="text" style="height: auto;" data-c="20 "> <span class="review"></span> amino acids used in polypeptide manufacture.</p></div><div class="q-explanation"><p><em>DNA structure is ideally suited to function for replication and storage of information.</em></p></div><div class="actions"><span class="score" data-score="0"></span><button class="btn btn-default btn-sm btn-xs-block text-xs-center check"><i class="fa fa-check-square-o"></i> Check</button></div></div><div class="totals"><span class="score"></span><button class="btn btn-success btn-block text-center check-total"><i class="fa fa-check-square-o"></i> Check</button></div></div><hr> <div class="panel panel-fucsia"> <div class="panel-heading"><a class="expander pull-right" href="#"><span class="fa fa-plus"></span></a> <div> <p>Just for fun</p> </div> </div> <div class="panel-body"> <div> <p>Everyone needs a bit of fun while they revise. Try this <a href="http://quizlet.com/64570605/match" target="_blank">Nucleic acids card match game.</a></p> <p>Can you reach the leader board?</p> <p style="text-align: center"><iframe height="500" src="https://quizlet.com/8332107/match/embed?i=xxmo&x=1jj1" style="border:0" width="100%">sandbox=&quot;allow-forms allow-pointer-lock allow-same-origin allow-scripts allow-top-navigation&quot;></iframe></p> </div> </div> <div class="panel-footer"> <div> <p>text</p> </div> </div> </div> <ul> </ul> </div> <div class="page-container panel-self-assessment" data-id="1160"> <div class="panel-heading">MY PROGRESS</div> <div class="panel-body understanding-rate"> <div class="msg"></div> <label class="label-lg">Self-assessment</label><p>How much of <strong>Nucleic acids 7.1 HL</strong> have you understood?</p><div class="slider-container text-center"><div id="self-assessment-slider" class="sib-slider self-assessment " data-value="1" data-percentage=""></div></div> <label class="label-lg">My 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