1. DNA, RNA & Protein Synthesis Chapters 12 & 13

2. The Structure of DNA

3. A little History YearScientist(s)Discovery 1928Frederick GriffithBacteria transfer genetic material from cell to cell. 1944Oswald Avery, Colin Macleod & Maclyn McCarty Griffith had discovered DNA! 1950Erwin ChargaffOf the four possible nucloetides: As = Ts & Gs = Cs. 1952Alfred Hershey & Martha Chase Genetic material in viruses is also DNA. 1952Rosalind FranklinDemonstrated that DNA is a helix. 1953James Watson & Francis Crick DNA is a double helix. 2000Craig Venter & Francis Collins Sequenced human DNA.

4. DNA In prokaryotes (no nucleus), DNA is circular. In eukaryotes, DNA is on the chromosomes in the nucleus.

5. Structure of DNA Double-stranded helix Linked nucleotides

6. Nucleotide Parts 1)Sugar - deoxyribose 2)Phosphate group (has element phosphorous) 3)Nitrogenous base Sugar and phosphate make the sides. Bases make the rungs.

7. Nucleotide Types 1)Adenine (A) 2)Thymine (T) 3)Cytosine ( C ) 4)Guanine (G) A bonds with T G bonds with C Called complementary base pairing

8. DNA Replication

9. When does it happen? Before cell division (mitosis or meiosis) Where does it happen? In the nucleus

10. DNA Replication: Step 1 Enzyme (DNA Polymerase) unwinds DNA

11. DNA Replication: Step 2 Enzyme attaches free nucleotides to the original strands until both strands are copied.

12. DNA Replication: Step 3 Replication occurs in many spots along the DNA until all parts are copied. Two identical strands are made. Now cell division can occur! http://www.stolaf.ed u/people/giannini/fla shanimat/molgenetic s/dna-rna2.swfhttp://www.stolaf.ed u/people/giannini/fla shanimat/molgenetic s/dna-rna2.swf

13. Replication in Different Cells In prokaryotes: Starts at a single point and proceeds in two directions until the entire chromosome is copied. In eukaryotes: Begins at many places and proceeds in two directions until the entire chromosome is copied.

14. RNA

15. Genes Section of DNA with the instructions to make 1 protein. Found in the nucleus.

16. Proteins Many amino acids linked together. Proteins are made in the cytoplasm. Click here for animation -> XXXX

17. Proteins are made in the cytoplasm by ribosomes, but the instructions for doing this (the DNA) can’t leave the nucleus.

18. How can this work??? RNA A single-stranded copy of DNA.

19. DNA vs. RNA RNA Chain of nucleotides. Sugar is ribose. Single-stranded. Bases are A,U,G,C. (U = uracil.) DNA Chain of nucleotides. Sugar is deoxyribose. Double-stranded. Bases are A,T,G,C.

20. Types of RNA Messenger RNA (mRNA) Copies DNA in the nucleus. Transfer RNA (tRNA) Brings amino acid to the ribosome for protein assembly. Ribosomal RNA (rRNA) Inside ribosome. Helps with translation.

21. To go from DNA to a Protein, there are two steps: 1)Transcription- mRNA makes copy of DNA 2)Translation- protein is made from mRNA

22. Transcription: mRNA copies DNA Step 1: enzyme (RNA Polymerase) unwinds DNA promoter: regions of DNA where the enzyme binds Step 2: mRNA bases make a copy of DNA http://www.stolaf.edu/people/giannini/flash animat/molgenetics/transcription.swf

23. Transcription (Part 2) Step 3: introns (bad bases) are removed, exons (good bases) are spliced together mRNA = AUACGUAC now = AUCUAC Step 4: cap and tail are added Step 5: mRNA leaves the nucleus for the cytoplasm. Link Link <- Click Here for Animation

24. Ribosomes & Protein Synthesis

25. Codons A section of three mRNA bases in a row that codes for one amino acid.

26. Anticodons The corresponding tRNA that carries the amino acid.

27. Translation: the mRNA is translated into a protein AnimationAnimation XXXX 1.) Ribosome finds the start codon, AUG, on mRNA. 2.) The corresponding anticodon on the tRNA binds into place. 3.) The ribosome reads the next codon & its corresponding anticodon binds. 4.) The ribosome bonds the two amino acids on the tRNA together. The tRNA lets go. 5.) This continues until a stop codon is reached. Then the last tRNA & ribosome fall off. 6.) The amino acid chain folds into its proper structure.

28. The central dogma of molecular biology= DNA-> RNA-> protein gene expression: process by which a gene produces its product, which carries out its function

29. Mutations

30. Changes in the DNA sequence that changes the protein it codes for. Two Types: 1.) Chromosomal Mutations 2.) Gene Mutations What are mutations?

31. Result from changes in a whole chromosome. 1.) gene deletions 2.) gene duplications 3.) gene inversions 4.) translocations Chromosomal Mutations

32. Parts of a chromosome break and rejoin, with a gene missing. Ex: Cris-du-chat Syndrome Gene Deletion

33. Most duplications have no phenotypic consequences. Gene Duplication

34. Part of a chromosome becomes oriented in the reverse of its usual direction. Usually no phenotypic consequences. Inversion

35. Part of a chromosome breaks off and attaches to a nonhomologous chromosome. Can lead to nonviable zygotes. Translocation

36. Occur at a single point in the DNA. Usually one nucleotide is substituted for another, changing an amino acid. Ex: Sickle Cell Anemia Point Mutations

37. Type of point mutation where an extra nucleotide is inserted or deleted, shifting the reading of codons, resulting in changes to ALL of the amino acids. Ex: Huntingdon’s Disease Frameshift Mutations Outcomes of Mutations <-Link

38. An agent that causes a change in DNA. Ex: smoke, high energy radiation (X rays, UV light, nuclear radiation), chemicals (dioxins, asbestos, benzene, cyanide, formaldehyde), and high temperatures. Note: In some cases, a gene mutation may have positive effects leading to evolution. Mutagen

39. Gene Regulation & Expression

40. How do cells regulate gene expression? Proteins bind to sections of DNA that control transcription. More complex in eukaryotes because cells are specialized.

41. Differentiation When new cells become specialized in structure & function during embryonic development. –In humans cells, this occurs 4 days after fertilization.