BCHM 3050 1st EditionExam # 3 Study Guide Lectures: 20-26Lecture 20 (February 27)What are the basic steps of PCR?First, denaturation occurs by heating the DNA at 90-95 degrees C for 1-3 minutes in order to separate the DNA strands. The next step is called annealing in which the temperature is decreased to 40-50 degrees C to allow the primers to join to the strands. Extension is the final step, and it involves heating to 70 degrees C for about 5 minutes. What is the difference between telomeres and telomerase?Telomeres recruit telomerase enzyme and telomerase brings in an RNA template in with it so that the DNA polymerase can fill in the rest of the nucleotidesLecture 21 (March 4)What was the name and basic idea of the proposal made by Beadle and Tatum in 1941?They were the one to propose that for every gene there is one enzyme (we know this to not be true now because one gene can influence many enzymes and one enzyme can influence many genes). This idea was called one gene, one enzyme.What were the differences of the three mutants used in their experiment?Mutant #1: Arg1 = without ornithineMutant #2: Arg2 = without citrullineMutant #3: Arg3 = without arginineLecture 22 (March 6)What is the “TATA” box?“TATA” box is a promoter region located at -25 bases from the start sight in the promoter region of eukaryotes. ALL eukaryote genes have this. It is universal and highly conserved across eukaryotes. What is the function of TFIIH?It phosphorylates the RNA polymerase; puts phosphate group onto RNA polymerase II and activates it, which is critical for eukaryotes to carry out transcription.Lecture 23 (March 9)What is the significance of the codon AUG?The start “AUG” in eukaryotes codes for methionine; in prokaryotes it codes for N-formyl methionine. Methionine (AUG) is the start codon and must be present in order for amino acids to be coded in the body; start translating where there is an AUG, and ignore everything that comes before this start codonHow do you calculate the total number of possible base combinations of an organism?You must take the total number of bases and raise it to the power of the number of bases that have to be combined to make an amino acid; so if you have 4 nucleotide bases and 3 together make a codon, than 43 = 64, which gives you the total number of possible base combinations, orcodons.Lecture 24 (March 11)How does a peptide bond form?Movement of the ribosome requires energy which is required by EF-G-GTP. Moves completed tRNA to E site, tRNA with multiple amino acids sits at P site, and leaves A site empty again as ribosome slides.Name some transitional differences in eukaryotes versus prokaryotes.- Eukaryote ribosome is heavier and more complicated- Eukaryotes – processing, capping, removing introns occurs (which doesn’t occur in prokaryotes)- Shine-Dalgarno recognized by the rRNA in prokaryotes- Prokaryote transcription is much fasterLecture 25 (March 13)Describe some differences in the formation of heterochromatin versus euchromatin.Deacetylation and methylation form heterochromatin, while acetylation and demethylation form euchromatin. Heterochromatin is a form of negative regulation, and euchromatin is a form of positive regulation.Lecture 26 (March 23)How is chromosome #19 an example of epigenetic regulation?This occurs on chromosome #19:- IGF2 and H19 are on the same chromosome (inherit one from mom and one from dad)- One can be turned off and passed onto offspring – Mom’s IGF2 is silenced and Dad’s H19is silenced across all humans- Example of epigenetics that is not affected by the environment- If you do not express H19 à Angelman Syndrome (no H19; mental disabilities and sterility issues)- If IGF2 is silenced à Prader-Willi Syndrome (no IGF2)What is alternative RNA splicing?Body makes one huge RNA strand with introns and exons. Then the spliceosome enzyme complex regulates which mRNA to create based on the exons included in splicing (alternate
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