DNA Structure 1. What are the parts of a nucleotide? Deoxyribose sugar, nitrogenous base, phosphate head. 2. Describe or show how the parts of a nucleotide are put together. Covalent bonds attach the different parts together. 3. There are two ways one nucleotide connects to another: describe or show both. Covalent bonding – Covalent bonding connects the deoxyribose sugar from one nucleotide to the phosphate head of another nucleotide. Complimentary bonding- Complimentary bonding is when two bases from are bonded together with weak hydrogen bonds. 4. What part of a DNA nucleotide is facing out, and what part faces in? The nitrogenous base groups face the inside of the helix and the sugar and phosphate groups face outward. 5. Where are the strongest bonds in a DNA molecule located, and where are the weakest located? The strongest bonds are located on the outside which is the sugar phosphate backbone and the weakest bonds are located where the bases bond together with weaker hydrogen bonds. 6. What are the 4 bases in DNA? Adenine Thymine Cytosine Guanine 7. Which bases connect/pair together? Guanine pairs with Cytosine and Adenine pairs with Thymine. 8. Describe WHY specific bases pair together, and how shape/structure plays a role. Adenine and guanine pair with Thymine and Cytosine because they are purines and purines are always attracted to pyrimidines like Thymine and Cytosine. Bases with two rings like Guanine and Adenine pair with bases with 1 ring like Cytosine and Thymine. 9. Describe or show the two different shapes of bases, and identify which base is which shape. 10. Describe or show the shape of a DNA molecule DNA replication 11. Why does DNA replicate? DNA replicates because whenever you need a cell, you need new DNA. When an organism grows, needs to heal, or make new cells DNA replicates. 12. Give an example of a real-life situation where DNA would need to replicate If you fall down and cut yourself, your body will make new cells to heal and your DNA will replicate. 13. Describe or show the first step of DNA replication The first step is when helicase breaks the weak bonds between original bases. 14. Describe or show how a new strand is made from a template strand The DNA building enzyme finds complementary free floating nucleotides and then connects them together one at a time to the old strand then it connects the new sugar phosphate backbone with the covalent bonds making a new strand. 15. How are bases added: one at a time, or all together? Bases are added one at a time. 16. What is a free-floating nucleotide? Free-floating nucleotides are nucleotides that have nitrogenous bases that are not bonded with anything yet. 17. Which bonds form first, as DNA replicates: the bonds on the inside the molecule or the bonds on the outside of the molecule? The hydrogen bonds form first and its on the inside of the molecule. 18. What is the final step of DNA replication? The final step would be when the DNA double helix retwists. 19. How many complete DNA molecules are create from one original DNA molecule? 2 complete molecules are created. 20. In every newly created DNA molecule, how much of the molecule is brand new? Half of the chain is part of the original DNA molecule and half is brand new.