homework 09

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Dec 6, 2023

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Version Beta Assignment 9 (50 pts) Name: Phoebe Lin In-lab work done #9 – PCR and Restriction Endonucleases Names: Note: 1-3 may be the same answer from both partners. 1. Designing a Protocol to Determine Alleles Present at the "Type O" SNP Locus activity A. Insert the upstream and downstream primers that made for the ‘Virtual PCR”. [4 pts] [paste primer pair that worked in your virtual PCR] Downstream: GGCCCAGAGTCCCAGGGCCTTGTGGGTCAGCCACTTCCTTTGGTGTCTGGGGCCAACTGCTTTGCCTGCCCCACCTA C Upstream: GACTTGCGTCTCTTGTTTCCTGTCCCTTTGTTCTCCAAAGCCCCTGCAAAGGCCTGATAGGTACCTCCTACCTGGGGA GGGGCAGC B. Using the primers you submitted for 1A, show the amplicon result that occurred. Bold the nucleotides that form the Kpn I restriction recognition site. [2 pts] GACTTGCGTCTCTTGTTTCCTGTCCCTTTGTTCTCCAAAGCCCCTGCAAAGGCCTGATAGGTACCTCCTACCT GGGGAGGGGCAGC GGCCCAGAGTCCCAGGGCCTTGTGGGTCAGCCACTTCCTTTGGTGTCTGGGGCCAACTGCTTTGCCTGCC CCACCTAC GACTTGCGTCTCTTGTTTCCTGTCCCTTTGTTCTCCAAAGCCCCTGCAAA GGCCTGATAGGTACCTCCTACCTGGGGAGGGGCAGCgggggttgggtgct ggggagggtttgttcctatctctttgccagcaaagctcagcttgctgtgt gttcccacaggtccaatgttgagggagggctgggaatgatttgcccggtt ggagtcgcatttgcctctggttggtttcccggggaagggcggctgcctct ggaagggtggtcagaggaggcagaagctgagtggagtttccaggtggggg cggccgtgtgccagaggcgcatgtgggtggcaccctgccagctccatgtg accgcacgcctctctccatgtgcagtaggaaggatgtcctcgt ggt_acc c cttggctggctcccattgtctgggagggcacattcaacatcgacatcctc aacgagcagttcaggctccagaacaccaccattgggttaactgtgtttgc
Version Beta catcaagaagtaagtcagtgaggtggccgagggtagagacccaggcagtg gcgagtgactgtggacattgaggtctctccttgtgttcaagacagagtgg ggtggcggccagccttgtcctcccagagggtagatgggaaaggtcattca tgcagcatcttactgagctcatgtgggctcgtgggctcgtgggctcgcca ggtcggtaaaacccagctccttctccagaggctgcgtctcacccagggat ggtggcttctgctgccccctcctctctgtaactgtggccggccgtcatgc tgagccaccccctcaatacaaggctccagatgtttcctgctcactgacca gagatagcaggagggggacacctgtttgctgtccttggaccctagaaaga ggatgctggcagagccgtggtcacttctctgtcagatGTAGGTGGGGCAG GCAAAGCAGTTGGCCCCAGACACCAAAGGAAGTGGCTGACCCACAAGGCC CTGGGACTCTGGGCC C. What is the length of the amplicon you obtained? What would be the lengths of the two fragments created by breaking the DNA at the Kpn I site you indicated? 3 pts entire product: __1180___ bp large fragment: __619___ bp small fragment: ___561___bp D. There were some Practical considerations listed in the Reading for designing a protocol such we are doing. Do the lengths that you obtained in 1C satisfy Practical consideration #1? [5 pts] entire product: __1180___ bp large fragment: __619__ bp small fragment: __561____bp Yes, the lengths satisfy the practical consideration #1 since the lengths of the fragments are different sizes. 2. Now, using the actual primers we are using in the PCR (6-1 and 6-2), paste the amplicon sequence results of your virtual PCR annotated as described in the instructions (just like in #1). Report the length of the entire PCR product and the approximate lengths of the two fragments that would be produced by a successful restriction digest at the SNP locus. [5 pt] entire product: ___734__ bp large fragment: __476___ bp small fragment: ___257___bp 3. This question is challenging. Ultimately, the answer to this is sort of an answer key for the “PCR gel” being run next week. If you work on this during lab, there is a high chance your TA will able to be sure that you have the correct concepts. This is a predictive exercise: IF you have DNA of X size, and IF you
Version Beta digest it with a restriction enzyme, then either the DNA is cut or the DNA is not cut. Further if the DNA is not cut, is it because of a failure to cut OR that the DNA is not supposed to be cut? This question is related to "important practical issues" #2 and #3 described in the "Designing a Protocol to Determine Alleles Present at the 'Type O' SNP Locus" section of this lab. Use the fragment lengths of the actual PCR product we are making in lab as determined in the previous question using the actual primers 6-1 and 6-2. NOT the virtual primers answer. The first row is done for you. On the ‘Digest condition’ column, those indicate if the enzyme is functioning or not. In the row filled out for you, both restriction enzymes are functional and working, and thus there is no known defect of Kpn I or BstE II. It does not mean that both are being used at the same time in the same sample of DNA, just that they are functional and should work if the DNA has the recognition sequence within it. Under ‘O,O homozygote’, you see that cell has two sub-columns underneath it. This is to imply that the exact same sample of DNA is used in both separate digests. Thus, there are 6 digests being performed on three distinct DNA samples. Recall that humans are diploid also…but we are not magically able to separate the chromosomes from each other. For the row where ‘Kpn I fails’, Kpn I is simply non-functional wherever Kpn I occurs in that row . A. In the table below, write ALL of the fragment sizes (in basepairs) that you would predict under the conditions described in the first column. Refer to Fig. 8 and consider the circumstances in actual human cells that are diploid. [13 pts] Genotype Digest condition O,O homozygote O,A/B heterozygote A/B,A/B homozygote Digest w/Kpn I (only) Digest w/BstE II (only) Digest w/Kpn I (only) Digest w/BstE II (only) Digest w/Kpn I (only) Digest w/BstE II (only) Both restriction enzymes are active 220;476* 696** 697**;220;476 696**;220;476 697 ** 220;476* ONLY Kpn I fails 696 696 697 220,476 697 220;476 ONLY BstE II fails 220;476 696 697; 220,476 696,697 697 697 Both fail 696 696 696,697 696,697 697 697 * Approximate, because the overhangs formed in the restriction digest do not contain complete basepairs.
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Version Beta ** Because the guanine is present at the SNP locus in the A/B allele, this product of the A/B allele is 1 bp longer than the product which is amplified from the O allele. As a practical matter, the difference in length is negligible. B. If you were going to include a single human-derived sample on the gel as a positive control, what kind of genotype should you use (i.e. what genotype would allow you to detect any of the three types of failures listed)? Explain your choice. [5 pts] ANSWER: If I were going to include a single human-derived sample on the gel as a positive control, I would use O A/B Heterozygous. If we use this genotype, we will be able to tell if the trait is expressed, its heterozygous, if it isn't expressed its homozygous dominant, if we get a different phenotype then it has to be homozygous recessive, or it has to be homozygous dominant. 4. Insert an image of your ‘practice gel’ loading. [1 pts] Postlab: Polymerase Chain Reaction and Restriction Endonucleases 5. Like many organisms, humans are diploid (if necessary, review Fig. 13 in Experiment 8). That means that each person has two copies (homologs) of each chromosome, including chromosome 9, which contains the ABO locus. In this class, we can describe the genotypes underlying some human blood types (i.e. type O or NOT type O) based on the state of the two alleles found at an individual's two "type O" SNP loci (one locus on each homologous chromosome 9). Recall that we defined the O allele as the version of the "type O" SNP having a deletion of the guanine and the A/B allele as the version of the "type O" SNP with the guanine present (Fig. 19.B. from Experiment 8):
Version Beta The table below has the possible states of each of the two homologous chromosomes with respect to the condition of its "type O" SNP locus (guanine present vs. guanine deleted). A. In the table below, fill in the blank after "alleles present:" with one of the following genotypes based on the alleles that would be present on the two homologous chromosomes: "O,O", "O,A/B", or "A/B,A/B". B. In the table below, fill in the blank after "H antigen modified?" with "yes" or "no" based on whether H antigens on the surfaces of red blood cells would be modified by the addition of A or B epitopes (review Fig. 18 of Experiment 8 if necessary). one homologous chromosome has the guanine doesn't have the guanine the other homologous chromosome has the guanine alleles present: _A/B, A/B_ H antigen modified? _yes_ alleles present: _A/B, O_ H antigen modified? _Yes_ doesn't have the guanine alleles present: _ A/B, O __ H antigen modified? _yes__ alleles present: __O,O___ H antigen modified? __no_ [ 4 pts] C. The phenotypes for human blood types are described based on immune reactions. A human has blood type O if none of the individual's H antigens are modified by addition of an epitope by the transferase coded for by the ABO gene. Such blood cannot elicit the kind of immune response stimulated by the presence of the modified H antigen (i.e. an A or B antigen). A human has one of the other blood types (not O; i.e. type A, type B, or type AB) if the individual has H antigens modified by the addition of an epitope. These blood types WILL elicit an immune response in individuals not having the same modified antigen. Of the three possible genotypes, which will result in a person having type O blood? Explain why having the type O allele on one chromosome won't necessarily mean that a person will have type O blood. [ 4 pts]
Version Beta Answer: The O/O homozygous genotype will result in a person having O blood. This is because it is a homozygous recessive trait. There is a guanine in both chromosomes which is why the H antigen is not modified on either chromosome. 6. View the video on the "Electrophoresis Concepts page" next week's lab on Brightspace. When the UV is on and the power is on and off, watch what happens to the mass markers of different sizes. Describe the relationship between the masses of the markers and their positions on the gel at any given time. [4 pts] Learning objective 10.2: describe the relationship between molecule size and the distance that it travels across an electrophoresis gel. Answer: When the UV is on, more fragments are able to be seen compared to when the UV is off, it’s harder to see the separation of fragments. Generally, the farther away the mass markers are from the gel, the smaller the fragments are because they are smalle meaning they move faster and further. BE SURE TO READ NEXT WEEK’S LAB prior to coming to lab and to sometime between this lab next week’s lab to log into Brightspace to do your Reading Assessment Questions. Five multiple choice questions, randomly selected from a large question bank.
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