4BBY1013 Summative literature assignment for Keats PDF

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4BBY1013 Summative literature assignment The summative literature exercise is designed to allow you to test your understanding of a short scientific article on DNA repair and to practice scientific writing. The aims of the assessment are: • To provide you with practice in reading and understanding scientific literature. •

To enable you to understand the criteria used to assess scientific writing at university level and to practice meeting those criteria.

The article complements Dr Chamber’s lectures but includes material he did not cover. You are not expected to learn this additional material for the midsessional test or final exam. A formative quiz is available on Keats to help direct your reading. The test gives you instant feedback. You do not have to do the quiz, but you will probably find it helpful to do so as it will lead you through the article. The quiz questions are also available in this document so that you can answer them ‘on paper’ before attempting them on Keats. The summative part of the assessment is for you to write a short abstract (summary) of the article and upload it to Keats. Guidance on Keats submission is available on the presentation slides – Feedback on the Formative Assessment. Instructions for the abstract are on page 2 of this document. The article The Encyclopedia of Life Sciences (ELS) is a useful electronic resource of articles on a huge range of subjects. King’s College London has a subscription to ELS and you can access it at: www.els.net You can search for the article by entering ‘DNA Repair’ in the ‘Enter keywords’ box and clicking on search els. From the search results select Posnick, L. M. and Samson, L. D. 2003. DNA Repair. In: Encyclopedia of Life Sciences (ELS). John Wiley & Sons, Ltd: Chichester DOI: 10.1038/npg.els.0000554 You will need to use the Institutional Log in to access the full article if you are not on campus. You can also navigate directly to the article via this link: https://doi.org/10.1038/npg.els.0000554

If you do this, you will need to Log In (top right) and make sure you choose ‘Institutional Log In’ rather than entering your email address. Choose Shibboleth,

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then UK Higher Education Network, then King’s College London and you will reach the KCL log in page.

Instructions for the abstract Write an abstract of the article (a summary that covers the main points of the article) in 350 - 400 words. Your abstract should be aimed at a reader with your level of knowledge i.e. another Common Year One student. It should be written in formal scientific language and in full sentences and paragraphs (not numbered points or bullet points). It should not contain images or tables, and it should not contain citations or references to other sources of information. Your abstract should be written in your own words. Some level of similarity to the original article is inevitable as you cannot change specialised scientific terms without altering their meaning, but you should not copy and paste or type word for word phrases and sentences from the article. Read the article, make notes without copying and pasting, and write your abstract from the notes. (You will be given more specialised guidance on avoiding plagiarism and use of the Turnitin software later on in the Skills for the Bioscience module.) You do not need to give details of the article in the abstract and you do not need to give a title. If you include a title it should not be counted in the word count. Please give your word count at the end of your abstract. You are advised to save your final work as a pdf file to upload it to the submission area on Keats. This is because it will preserve your document layout and not all file formats can be read and marked using our online marking system Marking criteria are over the page

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Marking criteria to be used for the abstract

Component

Excellent

Very Good

Good

Fair

Weak

Good selection of material (covers main points and excludes less important material) Language appropriate for the audience Understandable and clear Well structured: good flow of information Good layout (paragraph structure) Accurate Appropriate length

Please note that these criteria are not equally weighted in determining the overall mark.

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Quiz questions The questions below are available as a formative quiz on Keats that gives you instant feedback. You do not have to do the quiz, but you will probably find it helpful to do so as it will lead you through the article. It is recommended that you access and read the article and answer the test questions on paper, before logging on to the on-line test and entering your answers there.

1.

Which of the following examples of DNA damage can be classified as “base adducts”? MORE THAN ONE ANSWER MAY BE CORRECT. Select all that apply. There is a small negative marking penalty for an incorrect answer to stop you selecting all choices. a. b. c. d.

2.

Deamination of cytosine Methylation of adenine. Oxidation of guanine. Thymine dimer formation.

Which of the following agents of DNA damage are stated in the article to cause formation of base adducts? MORE THAN ONE ANSWER MAY BE CORRECT. Select all that apply. There is a small negative marking penalty for an incorrect answer to stop you selecting all choices a. Aflatoxin. b. Reactive oxygen species c. Ultraviolet light.

3.

Hydrolysis of which type of bond could create an “abasic site” in DNA? Select the Single Best Answer a. b. c. d.

4.

Glycosidic Bond. Hydrogen bond Phosphodiester bond Peptide bond DNA methyltransferases are involved in DNA repair. What is unusual about these enzymes? Select the Single Best Answer.

a. They are found in prokaryotes and eukaryotes b. They are called suicide enzymes because they cause cell death when DNA is severe.

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c. They are called suicide enzymes because they are inactivated by the reaction they catalyse. d. They use energy from visible light. 5. Which chemical change causes cytosine to change to uracil? Select the single best answer. a. Alkylation b. Deamination c. Oxidation 6.

What is the outcome if conversion of cytosine to uracil occurs? Select the single best answer. a. A CG base pair will be converted to an AT base pair. b. The DNA will be converted to RNA. c. A single base pair deletion.

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What is a key difference between Base Excision Repair (BER) and Nucleotide Excision Repair (NER)? Select the Single Best Answer. a. b. c. d.

8.

BER can remove a wider range of lesions than can NER. NER recognizes a distortion in the DNA rather than a specific lesion. NER involves DNA polymerase while BER does not. BER occurs in bacteria and humans, while NER occurs only in bacteria. What is the role of DNA ligase in DNA repair? Select the single best answer.

a. It catalyses the synthesis of new DNA to replace a damaged sequence that has been removed. b. It is involved whenever there is a “nick” in the DNA phosphodiester backbone that needs to be resealed. c. It removes damaged sequences to allow them to be replaced. 9.

What is different about Mismatch Repair (MMR) in comparison to the other repair pathways discussed in this review? Select the single best answer. a. b. c. d.

It is an excision repair process. It only occurs in prokaryotes, not eukaryotes. It requires DNA polymerase and ligase. It is repair of replication errors rather than DNA damage.

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10.

What is the role of DNA methylation in Mismatch Repair? Select the single best answer. a. DNA methylation is used in mismatch repair by humans but not by E. coli. b. Incorrectly added bases are methylated to tag them for removal. c. Methylation of the DNA allows the repair mechanism to recognise which strand is the correct template strand, and which is the newly made one with the error. d. Methylated DNA is the same thing as mismatched DNA as DNA is not normally methylated.

11.

Why does the “SOS response” of E. coli increase its mutation rate? MORE THAN ONE ANSWER MAY BE CORRECT. Select all that apply. There is a small negative marking penalty for an incorrect answer to stop you selecting all choices. a. It increases the tolerance of DNA polymerase to damage. b. Damaged DNA may be copied rather than repaired. c. It increases the exposure of E. coli to damaging chemicals.

12.

Which DNA repair pathway does not function in patients with xeroderma pigmentosum? Select the single best answer. a. b. c. d.

Base excision repair Direct repair. Mismatch repair. Nucleotide excision repair.

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