3. In future lectures we will describe a technique known as Northern blotting that can beused to detect RNA transcribed from a particular gene. Briefly, in this method a specificRNA is detected using a short segment of cloned DNA as a probe. The DNA probe,which is radioactive, is complementary to the RNA that the researcher wishes to detect.After the radioactive probe DNA basepairs to the RNA, the RNA is visualized as a dark(radioactive) band on an X-ray film. As shown here, the method of Northern blotting canbe used to determine the amount of a particular RNA transcribed in a given cell type. Ifone type of cell produces twice as much of a particular mRNA as occurs in another cell,the band will appear twice as intense. Also, the method can distinguish if alternativeRNA splicing has occurred to produce an RNA that has a different molecular mass.875 nucleotides675 nucleotides1Northern blot2-3Lane 1 is a sample of RNA isolatedfrom nerve cells.Lane 2 is a sample of RNA isolatedfrom kidney cells. Nerve cellsproduce twice as much of this RNAas do kidney cells.Lane 3 is a sample of RNA isolatedfrom spleen cells. Spleen cellsproduce an alternatively splicedversion of this RNA that is about200 nucleotides longer than theRNAproduced in nerve and kidney cells.The question:Let's suppose a researcher was interested in the effects of mutations on the expressionof a particular structural gene in eukaryotes. The gene has one intron that is 450nucleotides long. After this intron is removed from the pre-mRNA, the mRNA transcriptis 1100 nucleotides in length. Diploid somatic cells have two copies of this gene.Describe (or draw) the expected results of a Northern blot using mRNA from the cytosolof somatic cells, which were obtained from the following individuals:Lane 1: A normal individualLane 2: An individual homozygous for a deletion that removes the -50 to -100 region ofthe gene that encodes this mRNALane 3: An individual heterozygous in which one gene is normal and the other gene hada deletion that removes the -50 to -100 regionLane 4: An individual homozygous for a mutation that introduces an early stop codoninto the middle of the coding sequence of the geneLane 5: An individual homozygous for a three-nucleotide deletion that removes the AGsequence at the 3' splice site

Name: 3. In future lectures we will describe a technique known as Northern
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Description: 3. In future lectures we will describe a technique known as Northern blotting that can beused to detect RNA transcribed from a particular gene. Briefly, in this method a specificRNA is detected using a short segment of cloned DNA as a probe. The DNA