Several functional rnas have been mentioned in class

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Several functional RNAs have been mentioned in class: rRNA, which is used to translate mRNA into protein tRNA, which is used to translate mRNA into protein XIST, used in inactivation of the X chromosome snRNA, used in gene splicing miRNA, used in RNA interference Note: RNA polymerase is not correct here! 9. DNA replication is initiated by unwinding of the DNA helix, and synthesis on both template strands forming the leading and lagging strands. Briefly describe the four steps involved in lagging strand DNA synthesis following DNA unwinding. (4 points) 1. Primase copies RNA primers from DNA. 2. Elongation of RNA primers with new DNA by DNA polymerase. 3. DNA polymerase removes 5’ RNA primer and replaces with DNA. 4. Ligase creates phosphodiester bonds in backbone to join Okazaki-fragments. 10. Given sequence of a non-template strand of DNA as: 5’-ATGGACGTCTAG-3’. Write the sequence of the: 1) template strand (1 point) 3’- TACCTGCAGATC - 5’ 2) mRNA (1 point) 5’- AUGGACGUCUAG - 3’ 3) anti-codon (1 point) UAC CUG CAG AUC 11 . Briefly describe the stages of the mitotic cell cycle, including when the DNA is replicated and the chromosomes undergo segregation to daughter cells. You may use an illustration in your answer. (2 points) The mitotic cell cycle is separated into Interphase (G1, S phase, and G2) and mitosis (M). G1: cell growth, preparation for S-phase S-phase: DNA replication G2: cell growth, preparation for M M: mitosis, cell division, segregation into daughter cells – go into G1/G0 7
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Name________________________________ 12. Packaging of eukaryotic DNA in the nucleus is accomplished by the ordered binding of specific basic proteins along the chromosome to form chromatin. Diagram the 10 nm fiber form of chromatin to illustrate how the DNA and proteins interact. Label ALL the specific protein and nucleic acid components (including the length of relevant sections) for full credit. (6 points) For full credit the drawing will have the DNA wrapped twice around the histone core and histone H1 bound where the DNA enters and exits. The histone octamer is made up of two molecules each of H2A, H2B, H3 and H4. 160 bp of DNA wrap around the histone core and the linker between histones is 40bp . 8
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