3. This is the name of the small fragments of DNA that are replicated with several RNA primers in between them:

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1 Section A: Multiple Choice [15] 1. The central dogma states that: a) DNA is held in the nucleus, which is translated into an amino acid strand, which leaves the nucleus and is transcribed into a mrna strand b) Amino acids are held in the nucleus, which is translated into a mrna strand, which leaves the nucleus and is transcribed into a DNA strand c) RNA is held in the nucleus which is transcribed into a mdna strand which leaves the nucleus and is translated into an amino acid strand d) Amino acid are held in the nucleus, which is translated into a mrna strand, which leaves the nucleus and is transcribed into a DNA strand 2. What is the function of DNA polymerase III: a) To unzip the double stranded DNA chromosome c) To help relieve tension on the DNA strand due to being supercoiled b) To extend the new DNA strand by adding new nucleotides from 5 à3 d) To cut out the RNA primers and replace them with DNA nucleotides 3. This is the name of the small fragments of DNA that are replicated with several RNA primers in between them: a) Lagging strand b) Okazaki fragments c) Leading strand d) Replication fork 4. The process by which mrna is turned into a protein sequence is called: a) Elongation b) Translating c) Transcribing d) Initiation 5. What is the name of the enzyme that copies the double stranded DNA into a mrna: a) DNA polymerase I b) DNA polymerase II c) DNA polymerase III d) RNA polymerase 6. After the primary transcript (mrna) has been formed, what mediates the cutting of introns: a) Capping enzymes b) Spliceosomes c) Poly(A) polymerase d) RNA polymerase 7. In which direction is the mrna read by the ribosome: a) 3 à 5 b) 5 à 3 c) 1 à 3 d) 3 à 1 8. A trna molecule has a part that recognizes a sequence on the mrna, what is the name of this part: a) Anticodon b) Codon c) Template strand d) Amino acid

2 9. Which kind of mutation has the least impact on an organism: a) Deletion b) Insertion c) Missense d) Silent 10. What enzyme binds the sticky ends of cleaved (cut) DNA? a) Restriction enzymes b) Ligase c) RNA polymerase d) DNA polymerase 11. What does the Sanger method (Chain Termination) involve? a) Using labelled RNA primers as chain terminators to determine DNA sequences b) Using labelled deoxynucleotides as chain elongators to determine DNA sequences c) Using labelled dideoxynucleotides as chain terminators to determine DNA sequences d) Using labelled dideoxynucleotides as chain elongators to determine DNA sequences 12. What is the second step in the polymerase chain reaction (PCR)? a) Annealing the DNA primers b) Building a complementary DNA strand between the primers c) Placing DNA on gel electrophoresis d) Separating the strands of DNA 13. Which is the correct sequence of transcription? a) Initiation, elongation, termination b) Promotion, elongation, termination c) Initiation, termination, modification d) Start, elongation, modification 14. How is the lac operon inhibited? a) The lac repressor is not synthesized b) The lac repressor is inhibited by high concentrations of lactose c) RNA polymerase is inhibited by high d) Lactose is not present to bind with the lac concentration of lactose repressor 15. What happens to transcription when there are high levels of tryptophan in the cell? a) The repressor protein attaches to DNA but transcription occurs c) Trp binds to the operator, which stops transcription Section B: Matching and Ordering [15] b) Trp binds to the repressor protein, which binds to the operator to stop transcription d) Trp binds to the repressor protein, which binds to the promotor to stop transcription 1. Match the terms to their appropriate description. [5] C A. Introduced the transforming principle using S-strain and R-strain bacteria on Beatle and Tatum mice A Griffith E Hershey and Chase B. Used S-strain and R-strain bacteria to determine that DNA is the molecule that carries hereditary information C. Proposed the one gene-one enzyme hypothesis using bread mold mutants

3 B Avery, McLeod, McCarthy D Franklin and Wilkins D. Used X-ray crystallography to determine the molecular structure of DNA E. Worked with bacteriophage and radioactive P and S to determine that DNA is the genetic material, and not protein 2. Put the following events involved with protein synthesis into order by putting appropriate numbers in the blanks. 1 (one) will represent the first event; 10 (ten) will represent the last event. [10] A 5 cap and 3 poly A tail are added to the mrna transcript The stop codon is reached. No trna binds, the ribosomes and polypeptide are released. The mrna leaves the nucleus. The ribosome shifts one codon down, opening up its A site. The next trna binds. The DNA double helix is unwound beginning at the promoter sequence. The large ribosomal subunit clamps down on the trna carrying MET. Nucleotides are added by RNA polymerase creating a single strand of mrna. The 5 cap binds to the small subunit, and the mrna is scanned until the start codon is found. The polypeptide undergoes folding. The anticodon of the second trna binds at the A site and the amino acids at the P and A site are joined together. Section C: Labelling [10] 3. Label any 10 different things in the diagram of DNA replication below. You can make your own arrows if needed. [10]

4 Section D: Short/Long Answer [18] 4. Given a double stranded DNA sequence that is 14% guanine, what is the percentage of the other three bases, based on Chargaff s rule? [2] G=C; therefore, since G is 14%, C is also 14% When working with %, we are looking at a percentage of 100 Thus, there is [100-(14*2)] = 72% left, and since we know from Chargaff s rule that C=G and A=T; A+T = 72 à A=36% and T=36% 5. What if Meselson and Stahl s observations had looked like the tubes below? What would this mean for their conclusion and why? [3] Parents. First Generation Second Generation Parental DNA was labeled with heavy nitrogen (15N); new DNA strands were labelled with light (14N) After the first generation, we can see that there is no middle band (15N x 14N) o Only light (14N x 14N) and heavy (15N x 15N) o Similar results in the second generation These results demonstrate that the parental DNA strands come back together after replication and that new DNA only contains new strands à this means that DNA is replicating conservatively 6. Explain why DNA replication is slightly slower in the lagging strand of DNA than in the leading strand. [3] The two DNA strands are anti-parallel o The template stand is read from the 3 à5 direction o Thus, the leading strand is moving towards the replication fork, the lagging strand is moving away An accumulation of more steps results in the slower lagging strand: o RNA primase must place more RNA primers for DNA polymerase III to start replicating o DNA polymerase I has more primers to replace with DNA o Ligase has more Okazaki fragments (small fragments of DNA) and primers to seal together 7. The genetic code is often termed to be redundant. Using the Wobble hypothesis, describe the possible meaning of this term, and elaborate on the importance of this meaning as it applies to protein synthesis (from gene to protein). [2] Based on the wobble hypothesis, we know that the 1 st and 2 nd nucleotide of a codon must be strict, but the 3 rd nucleotide may be flexible, without changing the corresponding amino acid We can produce 61 different amino acids with only 20 trnas Redundant may mean; unnecessary, more than necessary, flexible, etc. Important as mistakes in codons and changing the resulting amino acid sequence can result in mutations o This allows room for error 8. Compare and contrast the lac and trp operon in terms of their components and how they function. How are they similar; how are they different? [3] Similar as both operons are regulated by a promotor and operator and involves a cluster of genes Different in result: o Lac operon à Lactose acts as an inducer When Lac is absent, transcription is off; presence of lactose will turn it on by binding to the repressor protein so that it may not bind to the operator o Trp operon à Tryptophan acts as a corepressor

5 When Trp is absent, transcription is on; presence of Trp will turn it off by binding to the repressor protein to allow it to bind to the operator 9. Given this DNA sequence: 3 CTACACACCGACCGTAACT 5 a) Write out the mrna sequence for it. [1] 5 GAUGUGUGGCUGGCAUUGA 3 b) What is the amino acid sequence for this mrna, using the codon chart provided on the last page. [1] MET CYS GLY TRP HIS - STOP c) If there were a mutation in the DNA that changed the 12 th nucleotide into a T, what would happen (what is the new protein sequence)? [1] MET CYS GLY STOP d) What kind of mutation is this? (Changing the 12 th nucleotide to T). [1] Substitution e) What would be the effect of this mutation? [1] Nonsense BONUS: Use your knowledge of biotechnology to solve this problem. Write your answers in full sentences. [3] You are assigned the task to help solve a bank robbery. In a small town where smoking is prohibited (not allowed) within 50 feet of all public places, a bank was robbed. No fingerprints or clothing were left behind. The only thing out of place was a cigarette butt right outside the door. How will you use biotechnology to find evidence related to the crime? Without including too much detail of the processes, list and describe the technique(s) you will use. Use polymerase chain reaction (PCR) to amplify the DNA found on the cigarette butt o Denaturation; annealing; elongation Can use the Sanger method (Chain reaction) to sequence the DNA and try and match it to the suspects o Use of ddntp as chain terminators to cut the DNA into different fragments o Gel electrophoresis is then used to sort out the fragments by length o DNA can be sequenced Can also use restriction enzymes to fragment the DNA à fingerprinting analysis using gel electrophoresis