151_153_Disc7_HW_Sp24

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Apr 3, 2024

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151-3 Introductory Biology - Discussion Homework 7 Week of October 23, 2023 Name: Reminder: Submit your homework on Canvas by the start of your scheduled discussion section! Please use a different font color so that your answers stand out. 1. A number of different types of RNA exist in prokaryotic and eukaryotic cells. Answer the questions about the following types of RNA to complete the table below. Types of RNA: Where do they function? How do they function in cells? mRNA tRNA rRNA snRNA 2a. To help you better understand what happens after transcription and before translation fill in the blanks in the paragraph below, using the following terms: introns ribosome nucleus 5’ cap alternative splicing cytoplasm primary transcript exons snRNAs nuclear pores poly-A tail spliceosome In eukaryotes, transcription creates a ________________ which is then modified while it is in the _____________. First, the ends of the RNA are modified by the addition of a ______ and a __________. Next, _______ are removed from the middle of the RNA, and the remaining _________ are spliced together to make a mature mRNA. The splice sites in the RNA are recognized by binding to the _________ in the molecular complex that performs this processing, which is called the ____________. This can in some cases produce different mRNAs through the process of _____________________. Mature mRNAs are then exported to the _______________ by being shuttled through _____________, and use the 5’ cap to help attach the mRNAs to the small subunit of the ____. 2b. What are the advantages of alternative (intron/exon) splicing in eukaryotes? More transcription goodness on the next page!

3a. Given your understanding of transcription and translation, fill in the blanks below for each nucleotide and polypeptide sequence. Assume that translation requires a start codon and that there is no processing of the pre-mRNA before translation. Remember to mark which end is 5’ and which is 3’ for each answer. Non-template strand of DNA 5′ C A G T A T G T A T G A C A A T G C A 3′ Template strand of DNA: ′ G _________________________________ __ ′ mRNA: ′ C ′ tRNA anticodon: _′ _ _ _ _′ _′ _ _ _ _′ _′ _ _ _ _′ _′ _ _ _ _′ _′ _ _ _ _′ 3b. List the sequence of Amino Acids (you can refer to the codon table found at the bottom of this document) : 3c. Were the 5 spaces shown in 3a above enough to list all the tRNA’s anticodons? If not, list the others below: 4. Ribosomes have A, P, and E, sites. In the table below, explain what the initial stands for and what occurs at each site during the translation process. It may help to draw a rough diagram of the ribosome and other constitutive parts of the process. Site: What does the initial stand for? What occurs at this site? A site P site E site 5. The table below lists five point mutations that may occur in the original strand of DNA. What happens to the amino acid sequence or protein produced due to each mutation? Note: Position 1 refers to the first base at the 3 end of the original template strand ′ . The last base in the DNA strand, at the 5 end, is at position 21. ′ Either use a genetic code table or the online translation tool: https://web.expasy.org/translate/ Original template strand: 3 TAC GCA A ′ G C AAT ACC GAC GAA 5 ′ 8 15 18 Mutation Type of Mutation Describe the effect on the amino acid sequence a. Substitution of T for G at position 8. b. Addition of T between positions 8 and 9.

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