1. WALT - To understand the structure of DNA as a polymer of nucleotides To understand the differences between DNA and RNA To understand the base pair ruling and the bonds involved in the helical DNA Structure WILF For you to describe in detail the structure of DNA and RNA including the nucleotides To be able to explain how DNA is held together

3. The DNA monomer:

4. Nucleotides are formed by condensation reactions H2OH2OH2OH2O H2OH2OH2OH2O

5. Each polynucleotide chain has two distinct ends a 3’ (‘three prime’) end  carbon 3 of the deoxyribose is closest to the end and a 5’ (‘five prime’) end  carbon 5 of the deoxyribose is closest to the end

6. With the phosphate group missing the sugar base molecule is called a nucleoside

8. Classify the following structure as that of a nucleoside or a nucleotide. Identify its components (sugar? base? phosphate?). Classify the following structure as that of a nucleoside or a nucleotide. Identify its components (sugar? base? phosphate?). Is this a purine or a pyrimidine?

9. The compound contains a sugar and a nitrogen base, but no phosphate group, so it is a nucleoside. The sugar has an -H in the 2' position and is therefore deoxyribose. The base has 1 ring, so it is a pyrimidine

10. Numbering the carbon atoms on deoxyribose:

12. THE GENERALIZED "FLATTENED HELIX" STRUCTURE REPRESENTING DNA

14. THERE ARE TWO HYDROGEN BONDS BETWEEN ADENINE AND THYMINE

15. THERE ARE THREE HYDROGEN BONDS BETWEEN GUANINE AND CYTOSINE

16. What sequence of bases of one strand of DNA is complementary to the sequence...? T-A-T-G-C-A-G Complement: A-T-A-C-G-T-C

17. Sugar – deoxyribose Phosphate Hydrogen bonds Purine bases Pyrimidine bases

18. 2) Explain the base pair rule that applies in double stranded DNA ADENINE binds with THYMINE, GUANINE binds with CYTOSINE 3) Explain how this differs in mRNA URACIL binds with ADENINE replacing THYMINE 4) Describe the purpose of the hydrogen bonds in double stranded DNA The Hydrogen bonds keep the base pairs together when in the DNA double helix. These can be broken easily which is important as the strands need to be unzipped during DNA replication and protein synthesis. 5) Describe the functional role of nucleotides Nucleotides are the building blocks of DNA and there precise sequence determines the genetic instructions for the organism

19. 6) Complete the following table DNARNA Sugar Present Bases present Number of strands Relative length DeoxyriboseRibose Adenine, guanine, cytosine and thymine Adenine, guanine, cytosine and uracil 2 1 Very long molecule Relatively short