Examine the chain of bases on the next page. Note that the deoxyribose sugar and phosphates are linked together to form a backbone. Which two carbons in a deoxyribose molecule are linked to a phosphate? (note that the carbons in deoxyribose are numbered).
2. DNA is double stranded (ds), meaning there are two of the above strands together. Try to assemble a ds DNA molecule with sugar phosphate backbones on the outside, and nitrogen bases on the inside. Use the chain of bases on the next page as one strand, use the loose bases provided to form the other strand. Note that the hydrogen bonds, represented by the dotted lines, must line up. Also, the bases must fit in a way such that a continuous strand is formed.
3. Observe your DNA molecule
What bases always pair together? (i.e., what base is always found paired with A?, with C?, G?, T?) Two bases that are always found across from each other are said to be complementary to each other.
4. Now look at the deoxyribose molecules in the two separate strands. What can you say about the orientation (direction) of the two strands with respect to each other?
5. Which end of each strand of DNA would you call the 5’ end?, the 3’end? Label these on your assembled ds DNA molecule (each of the two strands of DNA will have one 5’ end and one 3’end).
6. Experiment with your ds DNA molecule.
Can you form a continuous ds molecule with all the sugars and phosphates linking up if you mispair the bases? (say an A with an A etc?)
7. Can you do it if you have the two strands in the same direction
Examine the chain of bases on the next page. Note that the deoxyribose sugar and phosphates are linked together to form a backbone. Which two carbons in a deoxyribose molecule are linked to a phosphate? (note that the carbons in deoxyribose are numbered).
2. DNA is double stranded (ds), meaning there are two of the above strands together. Try to assemble a ds DNA molecule with sugar phosphate backbones on the outside, and nitrogen bases on the inside. Use the chain of bases on the next page as one strand, use the loose bases provided to form the other strand. Note that the hydrogen bonds, represented by the dotted lines, must line up. Also, the bases must fit in a way such that a continuous strand is formed.
3. Observe your DNA molecule
What bases always pair together? (i.e., what base is always found paired with A?, with C?, G?, T?) Two bases that are always found across from each other are said to be complementary to each other.
4. Now look at the deoxyribose molecules in the two separate strands. What can you say about the orientation (direction) of the two strands with respect to each other?
5. Which end of each strand of DNA would you call the 5’ end?, the 3’end? Label these on your assembled ds DNA molecule (each of the two strands of DNA will have one 5’ end and one 3’end).
6. Experiment with your ds DNA molecule.
Can you form a continuous ds molecule with all the sugars and phosphates linking up if you mispair the bases? (say an A with an A etc?)
7. Can you do it if you have the two strands in the same direction
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