What are the three parts of a nucleotide?

Transcription

1 Make It A Double Activity Sheet (Bead Model) Name: Date: Instructions: In groups of 2-3, you will each build a DNA molecule and then model the replication process. As you go through the steps, please answer the questions that go along that step while discussing what is happening with your partner. These answers will be shared in a class discussion at the end of the activity, so be prepared to explain what you did. Pre-activity questions: How do the bases pair in DNA? Ø pairs with Ø pairs with What are the three parts of a nucleotide? Activity Directions: 1. You have received a bag with pieces of a DNA molecule inside. Please count your pieces to make sure you have all of the following: a. 4 colors with 20 beads each b. 1 large animal bead c. 2 black and 2 sparkly pipe cleaners 2. First, make a strand of DNA. Decide which base each bead color corresponds to and write below: Adenine (A) = Thymine (T) = Guanine (G) = Cytosine (C) = Put the different color beads on a black pipe cleaner corresponding to the DNA sequence below: DNA Sequence: T-C-G-C-T-T-C-G-G-A-T-C-G-T-C-G-A-A Color Code: (first letter of color) 3. Now, make the complimentary strand of DNA for previous sequence Complimentary: Color Code: (first letter of color)

2 Add beads to a second black pipe cleaner and twist the two strands that you made around each other so that the complimentary strand s bases are lined up with the original or template strand s bases correctly. 4. Have the teacher check to make sure you coded your sequence right and matched up the base pairs using Chargaff s rule. Teacher Initials: 5. Now, you will replicate or synthesize the DNA: When new cells are made, DNA is replicated and a copy is given to each new cell. In this activity, imagine that your animal bead is the enzyme that makes DNA using a DNA template. What is this enzyme called? 6. Unwind the double stranded DNA helix and work with only one strand of DNA at a time. Put beads on a sparkly pipe cleaner that is, or creates base pairs, with the sequence of beads on the first pipe cleaner. This means wherever there is a cytosine, compliment it with a guanine. Where there is an adenine, compliment it with a thymine. 7. Once you have added nucleotides to complement the original strand of DNA, create a double helix by twisting the two strands together. Extra information: In the cell, the complementary base pairs stick together with hydrogen bonds. In the case of the C and G bond, there are 3 hydrogen bonds. In the case of AT, two hydrogen bonds. The DNA is going in opposite directions. DNA usually has 10 nucleotides per turn. 8. Repeat steps 6 & 7 with the other original strand. What was significant about using two different colored pipe cleaners? How many double stranded DNA molecules did you start out with? How many double stranded DNA molecules do you have now? 9. Have the teacher check your model(s) once you are finished Teacher Initials: Answer discussion Questions on next page!

3 Discussion Questions: What are nucleotides sequences used to make? Based on your above answer, what are some analogies of nucleotides? (things you could compare nucleotides to) What are some limitation of this model that might be different if you were working with a real DNA molecule? Did you accidentally put the wrong bead on the pipe cleaner? This is a mutation. We have talked about them a little bit in class, but this is when the sequence or code of base pairs changes. If the mutation remains, what will happen to the proteins being made? (answer this even if you said no to the above questions) What types of cells do you think would have the biggest impact on an organism and future offspring if a mutation occurred? (somatic or sex cells) Why? How might this affect evolution or changing of species over time?

4 Make It A Double Activity Sheet (Paper Model) Name: Date: Instructions: In groups of 2-3, you will each build a DNA molecule and then model the replication process. As you go through the steps, please answer the questions that go along that step while discussing what is happening with your partner. These answers will be shared in a class discussion at the end of the activity, so be prepared to explain what you did. Pre-activity questions: How do the bases pair in DNA? Ø pairs with Ø pairs with What are the three parts of a nucleotide? Activity Directions: 10. You have received a bag with pieces of a DNA molecule inside. Please count your pieces to make sure you have all of the following: a. 16 of each of the 4 bases (guanine, cytosine, adenine, and thymine) b. 16 sugars c. 16 phosphates d. tape 11. First, make 8 nucleotides with the following bases out of the materials provided: 2 T, 2 C, 2 G, and 2 A You may tape these together and use the shapes on each part to figure out the structure of the nucleotide. 12. Next, make a strand of DNA. Write down what color corresponds to the different bases below: Adenine (A) = Thymine (T) = Guanine (G) = Cytosine (C) = Line up the different color bases in a single strand of DNA like the sequence below: DNA Sequence: T-C-G-A Color Code: (first letter of color)

5 13. Now, make the complimentary strand of DNA for the previous sequence Complimentary: Color Code: (first letter of color) Line up the different color bases with the bases on the corresponding original strand. You may have to get creative here and turn the nucleotides to pair them. What would be holding these bases together in the middle of this double strand? 14. Have the teacher check to make sure you coded your sequence right and matched up the base pairs using Chargaff s rule. Teacher Initials: 15. Now, you will replicate or synthesize the DNA: When new cells are made, DNA is replicated and a copy is given to each new cell. In this activity, imagine that you are the enzyme that makes DNA using a DNA template. What is this enzyme called? 16. Unzip the double stranded DNA helix and work with only one strand of DNA at a time. Add bases that are, or create base pairs, with the sequence of bases on the first original strand. This means wherever there is a cytosine, compliment it with a guanine. Where there is an adenine, compliment it with a thymine. 17. Once you have added nucleotides to complement the original strand of DNA, the strands would normally twist together to create a double helix. You can try this if you tape your base pairs together in the middle, but it may be too difficult with paper. Extra information: In the cell, the complementary base pairs stick together with hydrogen bonds. In the case of the C and G bond, there are 3 hydrogen bonds. In the case of AT, two hydrogen bonds. The DNA is going in opposite directions. DNA usually has 10 nucleotides per turn. 18. Repeat steps 6 & 7 with the other original strand. How many double stranded DNA molecules did you start out with? How many double stranded DNA molecules do you have now? 19. Have the teacher check your model(s) once you are finished Teacher Initials: Answer discussion Questions on next page!

6 Discussion Questions: What are nucleotides sequences used to make? Based on your above answer, what are some analogies of nucleotides? (things you could compare nucleotides to) What are some limitation of this model that might be different if you were working with a real DNA molecule? Did you accidentally put the wrong base pairs together? This is a mutation. We have talked about them a little bit in class, but this is when the sequence or code of base pairs changes. If the mutation remains, what will happen to the proteins being made? (answer this even if you said no to the above questions) What types of cells do you think would have the biggest impact on an organism and future offspring if a mutation occurred? (somatic or sex cells) Why? How might this affect evolution or changing of species over time?

7 Name: DNA Quiz Date: Please answer the following questions without using your notes or other students in class. 1. What are the 3 parts of a nucleotide? a. b. c. 2. How do the four nitrogenous bases pair with each other? pairs with pairs with 3. What is the name of the enzyme that adds bases during DNA replication? 4. What two types of molecules make up the backbone of the DNA strands? & 5. Finish this strand of DNA: Original: ATG CCG CAT TCA GCA Complimentary: 6. Why is DNA replication important in organisms? 7. Summarize the process of DNA replication in complete sentences. 8. What is your student teacher s name?

8 Rubric For DNA Quiz Question # Answer Points 1 1 point each base, sugar, phosphate /3 2 1 point each A=T, C=G /4 3 DNA polymerase /1 4 1 point each sugar, phosphate /2 5 TAC GGC GTA AGT CGT /1 6 Any reasonable answer, student opinion /1 7 1 point for complete sentences, 1 point for steps (unzip, DNA polymerase pairs bases, new backbone is formed or two separate double strands are formed) /4 Total = /16