1. DNA R EPLICATION Packet #9 Chapter #8 1

2. R EVIEW OF O RGANIC M ACROMOLECULES Nucleic Acids 2

3. N UCLEIC A CIDS Nucleic Acids DNA {Double Stranded} Sugar Deoxyribose Phosphate Nitrogenous Bases Purines {2 Rings) Adenine Guanine Pyrimidines {1 Ring} Cytosine Thymine RNA {Single Stranded} Sugar Ribose Phosphate Nitrogenous Bases Purines {2 Rings} Adenine Guanine Pyrimidines {1 Ring} Cytosine Uracil 3

4. N UCLEIC A CIDS —N ITROGENOUS B ASES 4

5. N UCLEIC A CIDS DNA Strands 5

6. DNA S TRAND 6 DNA strands are composed of multiple DNA nucleotides joined together DNA Nucleotide A molecule composed of a nitrogen base, a sugar and a phosphate group

7. DNA S TRANDS II 7 Head 5’ end Has the phosphate group Tail 3’ end Has the hydroxyl group (OH)

8. DNA M OLECULE 8

9. DNA M OLECULES I 9 DNA molecules are composed of TWO DNA strands that are joined together. The TWO strands run in opposite directions. Hence, the two strands run anti-parallel.

10. DNA M OLECULES II 10 In order for DNA molecules to form, nucleotide pairs must occur between the two DNA strands. Nucleotide pairs occur when the nitrogenous bases, from the two strands, join together.

11. DNA M OLECULES III 11 The joining of nucleotides, from each strand, is NOT random AND occurs due to hydrogen bonds. A purine must always bind to a pyrimidine. However, there are limitations. Adenine  Thymine Cytosine  Guanine This is system of pairing is known as Chargaff’s rules.

12. T HUS F AR … 12 ChromosomeChromatinDNA MoleculesDNA Strands DNA Nucleotides Sugar Phosphate Nitrogenous Bases

13. F UNCTIONS OF DNA 13

14. F UNCTIONS DNA strands, which are composed of segments called genes, allow for the replication of the genetic code in order to maintain genetic continuity from generation to generation The replication of the genetic code allows the production of cellular enzymes These enzymes are used to the chemical activities of the cell and thereby the phenotypical characteristics of the organism. 14

15. DNA R EPLICATION 15

16. I NTRODUCTION 16 After Watson and Crick had determined how DNA strands are joined together, Meselson and Stahl determined that DNA replicated via a process known as semi-conservative replication. Each original strand is used to build a new DNA molecule.

17. I NTRODUCTION II 17 During DNA replication, the original strand can be known by two other names. Template strand Parental strand

18. I NTRODUCTION III 18 During DNA replication, the new strand produced can also be known as Complementary strand Daughter strand

19. I NTRODUCTION IV 19 There are two types of complementary strands. Leading strand “Normal daughter” Lagging strand “Crazy daughter” Complementary Strands Leading StrandLagging Strand AKA Daughter Strand

20. I NTRODUCTION V 20 Complementary (Daughter) Strand Type I “ Normal daughter ” Known as the LEADING STRAND Complementary (Daughter) Strand Type II “ The Crazy-One ” Called the ” Crazy-One ” because the strand is made as a result of combining “ Mini-me strands ” known as Okazaki Fragments Known as the LAGGING STRAND

21. DNA R EPLICATION —T HE P ROCESS C ONCISE V ERSION I 21 Enzymes, known as helicase, unzip the DNA molecule at locations known as the origin of replication. The unzipping occurs bi-directionally.

22. DNA R EPLICATION —T HE P ROCESS C ONCISE V ERSION II 22 DNA polymerases match the correct nucleotides, found on the template strand, to create the complementary strand. The lagging strand is completed in chunks known as Okazaki fragments which are later joined together.

23. DNA R EPLICATION —T HE P ROCESS C ONCISE V ERSION III 23 The template strands, combined with the complementary strands, create a new DNA molecule. There are two DNA molecules at the end of DNA replication. These DNA molecules are in the form of a double helix.

24. D URING DNA R EPLICATION ** 24

25. D URING DNA R EPLICATION ** 25 During DNA replication, any mistakes made, are traditionally repaired on the spot. More to come in AP Biology However, if the mistakes are not caught, these mistakes result in a mutation. Impacts the production of mRNA and proteins/enzymes.

26. R EVIEW 26