1. Nucleic Acids and DNA Replication

2. 1. What is the role of nucleic acid? 2. What is the monomer of a nucleic acid? 3. The monomer of a nucleic acid is made up of 3 things: a phosphate, base, and a _________________. 4. What is the difference between DNA and RNA? 5. A always pairs with T, and G always pairs with ____.

3. Nucleotides Include DNA and RNA

4. Components of a Nucleotide Phosphate Group (5’ end) Pentose Sugar (3’ end) Ribose in RNA Deoxyribose in DNA Nitrogenous bases Purine (2 rings) Adenine, A Guanine, G Pyrimidines (1 ring) Cytosine, C Thymine, T (only in DNA) Uracil, U (only in RNA)

5. Formation of Polynucleotides Dehydration reactions link nucleotides together Phosphodiester linkages are the bonds between the sugar of one nucleotide and the phosphate of the next New nucleotides can only be added to the 3’ end where there is an exposed hydroxyl group (from the sugar) This is why we say that DNA is built in a 5’ to 3’ direction Directionality in the structure of the DNA molecule influences how it functions

6. Formation of Polynucleotides

7. The DNA Double Helix

8. The two strands of the double helix are arranged in an antiparallel fashion, one of them going 5’-3’ and the other one going in the opposite direction

9. The “Backbone” Made up of alternating sugars and phosphates Connected by covalent bonds called phosphodiester linkages by dehydration reactions

10. The “rungs” of the Ladder Made up of nitrogenous bases Hydrogen bonded to each other The bases are hydrophobic and in their position inside the molecule they are shielded from the aqueous environment of the nucleus

11. Complimentary Base Pairing Each purine is bound to a pyrimidine A always to T (with 2 hydrogen bonds) C always to G (with 3 hydrogen bonds) Chargraff’s Rule: for any given species the % of Ts will by equivalent of the % of As while the % of Cs will be equivalent to the % of Gs

12. The DNA Double Helix

13. DNA vs. RNA DNARNA Number of Strands Pentose Sugar Nitrogenous Bases

14. Functions of DNA provides directions for its own replication directs RNA synthesis through RNA, controls protein synthesis (blueprints of the cell)

15. Function of Ribosomal RNA rRNA Together with proteins makes up the structure of the ribosomes, the site of protein synthesis

16. Function of Transfer RNA tRNA Recognizes the 3 base sequence on the messenger RNA and brings the appropriate amino acid to the ribosome fro protein synthesis