1. Objectives Investigate and review the history behind the discovery of the structure of DNA structure Understand the structure of DNA and its importance to carrying genetic information Understand the differences between DNA and RNA

2. 1952 - Francis H. C. Crick (1916- ) of Britain and James D. Watson (1928- ) of the U.S. made a model of the DNA molecule and proved that genes determine heredity. 1950’s - Maurice Wilkins (1916- ), Rosalind Franklin (1920-1957), Crick and Watson discover chemical structure of DNA, starting a new branch of science--molecular biology. 1966 - The Genetic code was discovered; scientists are now able to predict characteristics by studying DNA. This leads to genetic engineering, genetic counseling.

3. Structure of DNA Discovered by Watson and Crick and Franklin in 1952 Made of nucleotides –Parts of nucleotide Phosphate Sugar Nitrogenous Base –Adenine –Guanine –Cytosine –Thymine

4. RNA vs. DNA Ribonucleic Acid Ribose Nitrogenous Bases –Adenine –Thymine –Guanine –Cytosine Single Strand (Helix) Can leave the nucleus Contains a copy of the genetic code Deoxyribonucleic Acid Deoxyribose Nitrogenous Bases –Adenine –Uracil –Guanine –Cytosine Double Strand (Helix) Stays in the nucleus Contains the original genetic code

5. Look how incredibly smart we are Watson! I love science…I owe it all to my biology teacher.

8. Watch out boys you can’t deny me some credit.

11. Nucleotide Pairs Pyrimidines –Cytosine, Thymine Purines –Adenine Guanine Adenine always bonds with Thymine Cytosine always bonds with Guanine

13. Organization of DNA Double Helix- Twisted Ladder Twisted around Histone proteins. Twisted further into chromatin Twisted further into chromosomes

14. PurinesPyrimidines AdenineGuanine CytosineThymine Phosphate group Deoxyribose Figure 12–5 DNA Nucleotides Section 12-1 Go to Section:

15. Hydrogen bonds Nucleotide Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Figure 12–7 Structure of DNA Section 12-1 Go to Section:

16. Interest Grabber A Perfect Copy When a cell divides, each daughter cell receives a complete set of chromosomes. This means that each new cell has a complete set of the DNA code. Before a cell can divide, the DNA must be copied so that there are two sets ready to be distributed to the new cells. Section 12-2 Go to Section:

17. Chromosome E. coli bacterium Bases on the chromosome Prokaryotic Chromosome Structure Section 12-2 Go to Section:

18. Chromosome Structure of Eukaryotes Chromosome Supercoils Coils Nucleosome Histones DNA double helix Section 12-2 Go to Section:

19. Figure 12–11 DNA Replication Go to Section: Growth Replication fork DNA polymerase New strand Original strand DNA polymerase Nitrogenous bases Replication fork Original strand New strand

20. Chargraff – Determined that T  A and G  C

21. fromtoto make up Concept Map Section 12-3 also calledwhich functions toalso called which functions to can be RNA Messenger RNA Ribosomal RNA Transfer RNA mRNACarry instructions rRNA Combine with proteins tRNA Bring amino acids to ribosome DNARibosomeRibosomes Go to Section:

22. RNA DNA RNA polymerase Figure 12–14 Transcription Section 12-3 Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) Go to Section:

23. Figure 12–17 The Genetic Code Section 12-3 Go to Section:

24. Messenger RNA Messenger RNA is transcribed in the nucleus. Transfer RNA The mRNA then enters the cytoplasm and attaches to a ribosome. Translation begins at AUG, the start codon. Each transfer RNA has an anticodon whose bases are complementary to a codon on the mRNA strand. The ribosome positions the start codon to attract its anticodon, which is part of the tRNA that binds methionine. The ribosome also binds the next codon and its anticodon. mRNA Start codon Ribosome Methionine Phenylalanine tRNA Lysine Nucleus Figure 12–18 Translation Section 12-3 mRNA Go to Section:

25. The Polypeptide “Assembly Line” The ribosome joins the two amino acids— methionine and phenylalanine—and breaks the bond between methionine and its tRNA. The tRNA floats away, allowing the ribosome to bind to another tRNA. The ribosome moves along the mRNA, binding new tRNA molecules and amino acids. mRNA Ribosome Translation direction Lysine tRNA Ribosome Growing polypeptide chain mRNA Completing the Polypeptide The process continues until the ribosome reaches one of the three stop codons. The result is a growing polypeptide chain. Figure 12–18 Translation (continued) Section 12-3 Go to Section:

26. Substitution Insertion Deletion Gene Mutations: Substitution, Insertion, and Deletion Section 12-4 Go to Section:

27. Deletion Duplication Inversion Translocation Figure 12– 20 Chromosomal Mutations Section 12-4 Go to Section:

28. Regulatory sites Promoter (RNA polymerase binding site) Start transcription DNA strand Stop transcription Typical Gene Structure Section 12-5 Go to Section: