biology-class-12-unit-06-chapter-02-genetics-and-evolution-molecular-basis-of-inheritance-l-2-12-c4gywiag2zu

<h3 id="successuncommon-nucleotidessuccess-1"><Success>Uncommon nucleotides</Success></h3>
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<p><strong>2. Ribothymidine</strong></p>
<p><strong>3. Dihydrouridine (DHU)</strong></p>
<ul>
<li>
<p>It is a pyrimidine which is the result of adding two hydrogen atoms to a uridine, making it a fully saturated pyrimidine ring with no remaining double bonds</p>
</li>
<li>
<p>It is found in tRNA and rRNA</p>
</li>
</ul>
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<h3 id="successtypes-of-rnasuccess"><Success>Types of RNA</Success></h3>
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<ol>
<li>
<p>mRNA</p>
</li>
<li>
<p>tRNA</p>
</li>
<li>
<p>rRNA</p>
</li>
</ol>
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<p>======</p>
<h3 id="successtypes-of-rnasuccess-1"><Success>Types of RNA</Success></h3>
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<p><strong>Other small RNAs</strong></p>
<ul>
<li>
<p>Small Nuclear RNA</p>
</li>
<li>
<p>Micro RNA</p>
</li>
<li>
<p>Small Interfering RNA</p>
</li>
<li>
<p>Small Nucieolar RNA</p>
</li>
<li>
<p>Catalytic RNA(Ribozyme)</p>
</li>
</ul>
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<p>======</p>
<h3 id="successmessenger-rnasuccess"><Success>Messenger RNA</Success></h3>
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<ul>
<li>mRNA (messenger) used as template to make proteins</li>
</ul>
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<h3 id="successtransfer-rnasuccess"><Success>Transfer RNA</Success></h3>
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<p>Clover leaf model of t-RNA</p>
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<p>======</p>
<h3 id="successfunction-of-trnasuccess"><Success>Function of tRNA</Success></h3>
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<ul>
<li>tRNA (transfer) matches amino acids to mRNA to help make proteins</li>
</ul>
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<h3 id="successribosomal-rnasuccess"><Success>Ribosomal RNA</Success></h3>
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<ul>
<li>Ribosomal RNA forms an Important Part of both Subunits of the ribosomes</li>
</ul>
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<p>======</p>
<h3 id="successother-rnassuccess"><Success>Other RNAs</Success></h3>
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<ul>
<li>
<p>Small Nuclear RNAs</p>
</li>
<li>
<p>It plays a critical role in gene regulation by way of RNA splicing</p>
</li>
</ul>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-06-chapter-02-genetics-and-evolution-molecular-basis-of-inheritance-l-2-12-c4gywiag2zu-22a.jpg"></p>
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<h3 id="successother-rnassuccess-1"><Success>Other RNAs</Success></h3>
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<ul>
<li>
<p>MicroRNAs</p>
</li>
<li>
<p>These are small regulatory RNAs that are approximately 22 to 26 nucleotides in length</p>
</li>
<li>
<p>The existence of miRNAs and their functions in gene regulation</p>
</li>
<li>
<p>miRNAs have been shown to inhibit gene expression by repressing translation</p>
</li>
</ul>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-06-chapter-02-genetics-and-evolution-molecular-basis-of-inheritance-l-2-12-c4gywiag2zu-24.jpg"></p>
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<p>======</p>
<h3 id="successother-rnassuccess-2"><Success>Other RNAs</Success></h3>
<div style='float: left; width:99%;font-size:30px;text-align:left;'>
<ul>
<li>
<p>Small Interfering RNAs</p>
</li>
<li>
<p>Small interfering RNAs (siRNAs) are yet another class of small RNAs</p>
</li>
<li>
<p>Although these molecules are only 21 to 25 base pairs in length, they also work to inhibit gene expression</p>
</li>
<li>
<p>Specifically, one strand of a double-stranded siRNA molecule can be incorporated into a complex called RISC</p>
</li>
<li>
<p>This RNA-containing complex can then inhibit transcription of an mRNA molecule that has a sequence complementary to its RNA component</p>
</li>
</ul>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-06-chapter-02-genetics-and-evolution-molecular-basis-of-inheritance-l-2-12-c4gywiag2zu-24a.jpg"></p>
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<h3 id="successother-rnassuccess-3"><Success>Other RNAs</Success></h3>
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<ul>
<li>
<p>Small Nucleolar RNAs</p>
</li>
<li>
<p>Inside the eukaryotic nucleus, the nucleolus is the structure where rRNA processing and ribosomal assembly take place</p>
</li>
<li>
<p>Molecules called small nucleolar RNAs (snoRNAs) were isolated from nucleolar extracts because of their abundance in this structure</p>
</li>
<li>
<p>These molecules function to process rRNA molecules, often resulting in the methylation and pseudouridylation of specific nucleosides</p>
</li>
</ul>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-06-chapter-02-genetics-and-evolution-molecular-basis-of-inheritance-l-2-12-c4gywiag2zu-25.jpg"></p>
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<p>======</p>
<h3 id="successother-rnassuccess-4"><Success>Other RNAs</Success></h3>
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<ul>
<li>
<p>Catalytic RNA</p>
</li>
<li>
<p>nRNAs with enzymatic (specifically, catalytic) activity, such as the self- splicing molecules, are commonly referred to as ribozymes</p>
</li>
<li>
<p>Ribozymes have roles in mRNA processing, and splicing</p>
</li>
</ul>
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<h3 id="successwhy-thymine-instead-of-uracil-in-dnasuccess"><Success>Why thymine instead of uracil in DNA?</Success></h3>
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<ul>
<li>
<p>Despite uracil’s tendency to pair with adenine, it can also pair with any other base, including itself</p>
</li>
<li>
<p>By adding a methyl group (which is hydrophobic) and turning it into thymine, its position is reorganized in the double-helix, not allowing those wrong pairings to happen</p>
</li>
</ul>
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<p><img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-06-chapter-02-genetics-and-evolution-molecular-basis-of-inheritance-l-2-12-c4gywiag2zu-26.jpg"></p>
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<p>======</p>
<h3 id="successwhy-thymine-instead-of-uracil-in-dnasuccess-1"><Success>Why thymine instead of uracil in DNA?</Success></h3>
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<ul>
<li>
<p>Cytosine can deaminate to produce uracil</p>
</li>
<li>
<p>Only difference between them is the change from an O in uracil to an NH2 in cytosine</p>
</li>
<li>
<p>The problem is that, if uracil were a component of DNA, the repair systems would not be able to distinguish original uracil from uracil originated by deamination of cytosine</p>
</li>
<li>
<p>So using thymine instead makes it way easier and more stable, as any uracil inside DNA must come from a cytosine and so it can be replaced by a new cytosine</p>
</li>
</ul>
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<h3 id="successwhy-thymine-instead-of-uracil-in-dnasuccess-2"><Success>Why thymine instead of uracil in DNA?</Success></h3>
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<h3 id="successwhich-one-more-stable-dna-or-rnasuccess"><Success>Which one more stable DNA or RNA?</Success></h3>
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<ul>
<li>
<p>RNA has a 2’OH</p>
</li>
<li>
<p>The result is that under basic conditions, the hydroxyl group may be deprotonated and may act as an nucleophile and hydrolyze the phosphate bond</p>
</li>
</ul>
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<h3 id="successanswer-these-questionssuccess"><Success>Answer these Questions</Success></h3>
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<p><strong>Question 1 -</strong> What are the differences between DNA & RNA?</p>
<p><strong>Question 2 -</strong> Write the RNA Sequence of this given DNA</p>
<p>$\quad \quad \quad \quad $  sequences:5 ‘ATCCGTAATCGTTC 3’</p>
<p><strong>Question 3 -</strong> Give the function of following RNA -</p>
<p>a. mRNA</p>
<p>b. tRNA</p>
<p>c. rRNA</p>
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<img alt="image" src="https://temp-public-img-folder.s3.ap-south-1.amazonaws.com/sathee.prutor.images/subject-images/iitpal/image/biology-class-12-unit-06-chapter-02-genetics-and-evolution-molecular-basis-of-inheritance-l-2-12-c4gywiag2zu-30a.jpg"></p>