DNA and Mitosis D

BIO 110 – Dr. Ely • • Lecture Assignment 5 – DNA and Mitosis Download the Assignment 5 answer sheet and type your answers into the spaces provided. Then upload to the assignment dropbox as a Word file. Grading: Each question is worth 1 point unless otherwise specified. 62 possible points Ch. 9.1, 9.2, 9.3, 9.4 – DNA Biology Don’t forget to watch my video #15 on the structure of DNA. Also, this 5-minute video has some great visualizations of the structure of DNA: https://youtu.be/o_-6JXLYS-k 1. Roughly 15% of all cases of the common cold are caused by coronaviruses. Look up ‘coronavirus’ on Wikipedia and read about it. What kind of genetic material do coronaviruses possess, DNA or RNA? 2. The picture on the left below is an image of DNA created by a method called X-ray crystallography. It was produced in the laboratory of the scientist pictured in the image on the right. Her work was crucial for the elucidation of the structure of the DNA molecule by James Watson and Francis Crick, who were awarded the Nobel prize for their work in 1962. The researcher pictured below was never given credit for her pivotal role in this breakthrough discovery. What was her name? 3. The nucleotide is the monomer of nucleic acids, and a single nucleotide is composed of three parts. Which one part of a nucleotide is the one that might differ between any two DNA nucleotides? 4. Which two parts of nucleotides make up the ‘backbone’ of a DNA strand? 5. The nitrogenous bases of opposite strands of DNA are complementary, meaning they have only one other nucleotide they will pair with. Which of the choices best represents the base-pairing rules? A) A–C, G–T B) A–T, G–C C) A–G, C–T D) A–A, G–G 6. In a single DNA molecule, if the amount of DNA nucleotides containing a cytosine (C) base is 30%, what percentage of DNA nucleotides containing a thymine (T) base must there be? (Hint: think about the percentage of G first, then consider A and T) 7. In your own words, why does a cell need to perform DNA replication? (be specific; it is not “repair and growth”, that is the reason why cells divide) (2pts) 8. In your own words, why can’t DNA replication proceed without helicase? (2pts) 9. What kind of bond does helicase break? 1 10. If DNA polymerase makes a mistake, what do we call such an error? For each description, choose whether DNA or RNA is the molecule being described. 11. The molecule is only a single strand. DNA or RNA? 12. The molecule contains the bases A, T, C, and G. DNA or RNA? 13. The molecule can be found in the cytoplasm. DNA or RNA? 14. The nucleotides contain ribose. DNA or RNA? 15. The molecule is only found in the nucleus. DNA or RNA? 16. Identify the three types of RNA involved in gene expression. 17. Which type of RNA (from your answer in #16) is created during transcription. 18. Which enzyme performs transcription? 19. What is the name for the three-nucleotide unit of mRNA that codes for an amino acid? 20. Which kind of RNA contains the anticodon? 21. Which structure, involved in translation, is made of rRNA and proteins? 22. Which phase of translation, initiation, elongation, or termination, consists of adding amino acids to a growing polypeptide? Three of the following sentences (A through F) have a single-word mistake in them. For questions 23-25, identify which three are incorrect and clearly describe how they should be corrected. A. Translation is the process of building a carbohydrate from the information in a molecule of mRNA. B. The ribosome binds the mRNA transcript and begins translation at the start codon. C. During translation, tRNA molecules carry triglycerides to the ribosome. D. The P site holds the tRNA molecule carrying the growing polypeptide. E. An ionic bond is formed between the growing polypeptide and each newly-arrived amino acid. F. Multiple ribosomes can access a single mRNA transcript to produce many copies of proteins quickly. 23. The first incorrect sentence is ____. How should it be corrected? 24. The second incorrect sentence is ____. How should it be corrected? 25. The third incorrect sentence is ____. How should it be corrected? Suppose a point mutation changes a stretch of DNA that RNA polymerase is about to transcribe. The mutation changes the base sequence from TAA to TGA. Answer questions 26-28. 26. Which amino acid was originally encoded by the DNA? 27. Which amino acid will now be encoded following the mutation? 28. Based on your understanding of proteins/enzymes, and not any specific example, why can such a small mutation in DNA lead to disease or even death? (Remember what is important for a protein to function properly.) (3pts) 2 Chapter 6.2 – Cell Cycle + Mitosis (videos 41+42) Use the following terms to identify the different phases of the cell cycle labeled in the diagram to the right: G2; Telophase; Interphase; Cytokinesis; Prophase; Anaphase; G1; Metaphase; S; Mitosis 29. Identify A 30. Identify B 31. Identify C 32. Identify D 33. Identify E 34. Identify F 35. Identify G 36. Identify H 37. Identify I 38. Identify J For questions 39-48 use the same terms from the list above to name the part of the cell cycle that best fits each description: 39. Sister chromatids are pulling away from each other 40. Last phase of interphase; cell prepares for mitosis 41. The non-dividing portion of the cell cycle 42. Nuclear division; consists of four phases 43. Chromosomes begin to condense and nucleus starts to dissolve 44. Stage of cell cycle when DNA replication occurs 45. Chromosomes begin to loosen and nuclei start to reappear 46. Division of the cytoplasm; 2 daughter cells created 47. First stage of interphase, cell grows and conducts normal activities 48. Chromosomes line up along the spindle equator 49. Chromosomes occur in two different forms inside the nucleus of a cell. What do we call the loose form of chromosomes, when they appear as thin threads before mitosis even begins? 50. Following DNA replication two sister chromatids are held together by a bundle of proteins near the middle of the chromosomes. What is the name for this region where the two chromatids are held together? 51. Which type of cell forms a cleavage furrow at the end of mitosis, an animal cell or a plant cell? 3 52. During class, we identified the two purposes of cell division. What were these two purposes? The picture to the right shows many plant cells at various points in the cell cycle. Refer to this picture for questions 53-58. 53. Which letter is pointing to a cell in Prophase? 54. Which letter is pointing to a cell where you can see a cell plate? 55. In which cell, A or C, are the chromosomes in the form of chromatin? 56. In which cell are the chromosomes aligned at the spindle equator? 57. In which cell would you expect to see two new nuclei forming? 58. Which phase of mitosis is E? 4 …
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