DNA

1. DNA

3. Classify the following as either an atom or compound of DNA and RNA. • Nitrogen Base • Compound • Carbon • Atom • Oxygen • Atom • ATP • Compound • Sugar • Compound

4. The functioning of DNA and RNA are affected by various enzymes. Sometimes, environmental factors can influence how these enzymes work. Which of these are factors that can change enzyme functionality? • A. color • B. concentration • C. location • D. pH • E. temperature • Answer: B, D, and E

5. What is this molecule? What is its function in living things? Where in the cell is it found? What can we learn from studying this molecule?

6. The answer lies in the molecule that provides the blueprint for all of the traits in an organism. This molecule is called DNA. DNA (deoxyribonucleic acid) is a nucleic acid that carries the code for each and every characteristic that is expressed by an organism.

7. The race is on! In the late 1940s, there was an intensive effort to discover the structure of the DNA molecule. Scientists were aware that DNA was responsible for the passage of traits from parents to offspring, but they wanted to know what it looked like in order to get a better understanding of how it functioned. A team of scientists made the discovery in 1953. The team consisted of James Watson, an American, and Francis Crick, Maurice Wilkins, and Rosalind Franklin, all from Great Britain.

8. Rosalind Franklin is usually left out of the story of DNA’s discovery because she was not actually working in the lab at time. However, without her contribution, it is unlikely that the rest of the scientists would have been successful. Franklin was an X-ray crystallographer. She took pictures of molecules using cameras (a high-tech method at the time). One day, a student in her laboratory took a picture of DNA and put it into a drawer. It was labeled Photograph-51.

9. After Franklin had left the lab, Maurice Wilkins was cleaning up, and he came across the image. He immediately alerted Watson and Crick, and within a short period of time, they had built a model structure of the DNA molecule. They called it a double helix.

10. Videos • Discovery of DNA Structure • What does the structure of DNA look like? Who were the scientists involved with the discovery? • https://app.discoveryeducation.com/player/view/assetGuid/a4b339f1-e6d1-448d-a955-8ad7a9a669da • Nucleic Acid • https://app.discoveryeducation.com/player/view/assetGuid/7cc9f645-81ec-4077-92fb-0881163229fa

11. Video Review • What is the structure and function of DNA? • Where is DNA located? • Why are some traits passed from parent to offspring?

12. DNA codes for all of the traits an organism expresses. During the process of protein synthesis, DNA codes for the formation of strands of another nucleic acid called RNA (ribonucleic acid). Like DNA, RNA carries information. In this case, it determines which proteins will be formed.

13. Venn Diagram • Begin two Venn diagrams: • One comparing and contrasting the structures of DNA and RNA • One comparing and contrasting the functions of DNA and RNA. • Fill In your Diagram as you view the next few slides and watch the videos in order to summarize the similarities and differences between the structures and functions of DNA and RNA.

14. DNA • As living things grow, their cells must grow and divide. This cellular division results in the original parent cell and the new daughter cell. The chromosomes store the hereditary information that is passed to the daughter cell and tells the cell its function. The chromosomes reside in the nucleus and are made of genes and in turn are made of DNA. DNA is made of four nitrogen containing chemicals: adenine, guanine, cytosine, and thymine. The combinations of these chemicals determine the genetic code to carry out the life functions of the cells. • https://app.discoveryeducation.com/player/view/assetGuid/39cf803f-e612-4a71-8cad-8bf0d429e4ec

15. Genes: The Blueprint of Life • Presents a description of the hereditary information found in the nucleus of every cell. Describes nucleotides, protein functions, and chromosomes. • https://app.discoveryeducation.com/player/view/assetGuid/a45fd565-0a0b-4dbd-8f90-9f2876e16211 • Summarize in writing, in their own words the relationships among DNA, genes, and chromosomes.

16. Review • Who discovered DNA’s Structure? • How did they determine the structure of DNA? • What is the name of the photograph in which they looked at? • What is the structure/shape of DNA? • What are the 4 bases that make up DNA? • What bases pair with each other?

17. What are the components of DNA and RNA? • Like other biological molecules, nucleic acids are large polymers made up of smaller repeating units, or monomers. Nucleic acid monomers are called nucleotides. DNA contains four different nucleotides, each with a different chemical base: adenine (A), guanine (G), thymine (T), and cytosine (C). The bases can form weak hydrogen bonds with each other, but only certain complementary bases can bond. Guanine bonds only with cytosine, while adenine bonds with thymine. • RNA also contains four different nucleotides, three of which are identical to DNA bases. In RNA, the base uracil (U) replaces thymine. Uracil is complementary to adenine.

18. In addition to the bases, nucleotides also contain a 5-carbon sugar (Deoxyribose in DNA and ribose in RNA) and a phosphate group. The sugar and phosphate groups of adjacent nucleotides bond together to form a backbone. Scientists label the carbons in the sugar from 1' to 5' based on their position in the molecule. The phosphate group is attached to the sugar at the 5' carbon. The 5' end of one nucleotide bonds to the 3' carbon of the adjacent nucleotide to form the sugar-phosphate backbones. The two backbones of the double helix run in opposite directions. One sugar-phosphate chain runs in the 5' to 3' direction and the other runs in the 3' to 5' direction.

19. Antiparallel Strands

20. DNA contains two separate, complementary strands of deoxyribonucleotides held together by hydrogen bonds. The two strands wind together to form a spiral shape called a double helix. In contrast, RNA is made up of a single strand of ribonucleotides. Although RNA is single-stranded, some RNA molecules form folded structures, and like proteins, these folded RNA molecules perform various functions like catalyzing reactions and transporting molecules. • DNA and RNA are very large molecules, but they follow the same chemical rules that apply to smaller molecules. For example, the charge on DNA’s phosphate backbone is negative. This makes DNA a polar molecule, and it behaves like other, smaller polar molecules, such as water. Because DNA is polar, it dissolves easily in water, and it does not dissolve in nonpolar solvents, such as alcohol.

21. The Structure of DNA • Nucleotide – in a nucleic acid chain, a subunit that consist of a sugar, a phosphate, and a nitrogenous base.(The Building Block of DNA.) • DNA – Code – Because the sugar-phosphate “backbone” of the DNA molecule is always the same, the parts of the DNA molecule that are different, the nitrogen bases, must contain the genetic code.

22. The Structure of DNA • Many nucleotides join together to make a strand. • Purines – A nitrogenous base that has a double-ring structure, adenine or guanine • A – Adenine • G - Guanine • Pyrimidines – a nitrogenous base that has a single-ring structure; in DNA, either thymine or cytosine. • T – Thymine • C – Cytosine • Base pairs are held together by hydrogen bonds.

23. Chargaff’s Rules: • Erwin Chargaff (11 August 1905 – 20 June 2002) was an Austro-Hungarian biochemist that immigrated to the United States during the Nazi era and was a professor of biochemistry at Columbia University medical school. Through careful experimentation, Chargaff discovered two rules that helped lead to the discovery of the double helix structure of DNA. • The rules of base pairing (or nucleotide pairing) are: • A with T: the purine adenine (A) always pairs with the pyrimidine thymine (T) • C with G: the pyrimidine cytosine (C) always pairs with the purine guanine (G) • This is consistent with there not being enough space for two purines to fit within the helix and too much space for two pyrimidines to get close enough to each other to form hydrogen bonds between them.

24. But why not A with C and G with T? • The answer: only with A & T and with C & G are there opportunities to establish hydrogen bonds (shown here as dotted lines) between them (two between A & T; three between C & G). These relationships are often called the rules of Watson-Crick base pairing, named after the two scientists who discovered their structural basis. • The rules of base pairing tell us that if we can "read" the sequence of nucleotides on one strand of DNA, we can immediately assume the complementary sequence on the other strand. • The rules of base pairing explain the phenomenon that whatever the amount of adenine (A) in the DNA of an organism, the amount of thymine (T) is the same (called Chargaff's rule). Similarly, whatever the amount of guanine (G), the amount of cytosine (C) is the same.

26. Video Review:Structure of DNA • Outlines the general structure of DNA, and explains how DNA is paired and forms a double helix. • https://app.discoveryeducation.com/player/view/assetGuid/061b52c1-79db-4f56-857f-5c46b885b8d4 • Traces the history of DNA, from Erwin Chargaff's realization that the amounts of adenine always equal thymine and the amounts of guanine always equal cytosine in DNA, to the discovery that DNA's shape is a double helix. • https://app.discoveryeducation.com/player/view/assetGuid/d603dda3-1538-4a1d-a568-62b7ae27cb30

27. Practice Problems • Draw 6 nucleotides 5’ to 3’ and the adjacent 3’ to 5’ on a piece of paper. • Write the complimentary DNA strand for each given strand of DNA. • 1. CGTAAGCGCTAATTA • 2. TCTTAAATGATCGATC • 3. AATGAATAGCTAGCTT • 4. GGCATTCGCGATCATG • 5. CGTTAGCATGCTTCAT • 6. ACTAACGGTAGCTAGC

28. Answers • 1. GCATTCGCGATTAAT • 2. AGAATTTACTAGCTAG • 3. TTACTTATCGATCGAA • 4. CCGTAAGCGCTAGTAC • 5. GCAATCGTACGAAGTA • 6. TGATTGCCATCGATCG

29. Packing Peanut DNA Models - Lab

30. INSTRUCTIONS: Use only BIODEGRADABLE packaging peanuts. They can be purchased from office supply store or department. Use a wet paper towel or sponge to moisten the ends of the peanut as needed. Place wet ends together to BOND. Let dry for a few seconds.

31. INSTRUCTIONS: Your model should be 6 nucleotides minimum. – 3 Nucleotides on one side, 3 Nucleotides on the other side.(18 Peanuts) Each packing peanut must represent a part of the DNA nucleotide. The parts must all bond correctly. LOOK IN YOUR NOTES ON HOW THE STRUCTURE OF A DNA NUCLEOTIDEIS. HINT: Your models will be easier to assemble if you make the nucleotides first.

32. INSTRUCTIONS: 5. Demonstrate Chargaff’s rule. You must use all four types of DNA nucleotides. Look in your notes for the CHARGAFF’S BASE PAIRING RULES 6. All peanuts must be labeled. Use a key or write on the peanuts directly with a marker. Erwin Chargaff

33. INSTRUCTIONS: Model should exhibit helical shape and antiparallel nature.

34. GRADING RUBRIC: EXCEEDS EXPECTATIONS = All of the requirements done. MEETS EXPECTATIONS= Not helical or antiparallel OR missing one other requirement. APPROACHES EXPECTATIONS = Not helical or antiparallel AND missing one other requirement. EMERGENT = Not helical or antiparallel AND missing two or more other requirements.

35. Exceeds Expectations

36. Meets Expectations

37. Approaches Expectations

38. Emergent A=Yellow, G=Red T=Orange, C= Blue Phos=Green, Sug=Black

39. TEACHRE EVALUATION: Scoring Rubric