3. Defined: Molecule that stores genetic information Monomer: Nucleotide Millions of nucleotides bond to make nucleic acids Gene: section of DNA that holds instructions to build a protein

4. Nucleotide Structure Three parts –Sugar molecule –Phosphate group –Nitrogen base (A, T, C, or G) Nucleotides combine to make nucleic acids A pairs with T C pairs with G T C G A C

6. Sugar (Deoxyribose) connects with the phosphate group 4 Different Bases: –Adenine (A) –Thymine (T) –Guanine (G) –Cytosine (C) Chargaff’s Rules: –Rule: amount of A = amount of T –Rule: amount of C = amount of G Human DNA: ~3 billion pairs CTAATGT

7. James Watson and Francis Crick identified DNA’s structure in 1953 Double Helix: spiral shape of DNA Nucleotide strands are connected by a hydrogen bond

8. Defined: Process of copying DNA –During interphase (S-stage) Step 1: DNA Helicase “unzips” the two DNA strands (breaks the H bonds) Step 2: Free floating nucleotides (A, T, C, G) match up Step 3: DNA Polymerase reconnects the two strands

9. Step 1: DNA Helicase “unzips” the two DNA strands (breaks the H bonds) DNA Helicase Step 2: Free floating nucleotides (A, T, C, G) match up Step 3: DNA Polymerase reconnects the two strands DNA polymerase Both DNA molecules are identical Both DNA molecules contain one original strand and one new strand. This is called the: semiconservative model DNA Polymerase

10. Mutation: change in DNA sequence Mutations can be corrected –Enzyme “proofreads” DNA and check/correct errors Pre-repair: 1 in 10,000 nucleotides has an error Post-repair: 1 in 1 billion nucleotides has an error enzyme

12. Single nucleotide strand Sugar: Ribose 4 Bases: –A: Adenine –G: Guanine –C: Cytosine –U: Uracil U replaces T Three Types of RNA

13. mRNA Function: Copies the DNA code and moves to a ribosome Link between DNA & Protein Allows ribosome to create a protein Location: Starts in nucleus… moves to ribosome

14. tRNA Function: Transfers amino acids from the cytoplasm to the ribosome Ribosome will link amino acids together to form a protein Location: Cytoplasm Transfer RNA Amino acid Proline Amino acid Serine

15. rRNA Function: components of ribosomes

16. Transcription Defined: Process of making mRNA from DNA Step 1: RNA Polymerase separates the DNA nucleotides Step 2: Free floating RNA nucleotides match with the DNA Reminder: U replaces T Step 3: mRNA breaks free in separate pieces Step 4: mRNA processing takes place –Unused portions (introns) are removed and the used portions (exons) bond together Step 5: Final mRNA strand travels to ribosome Step 6: DNA recombines to be used again U| G|G| C| A| G|G| U| C| A| U| C| G|G|

17. RNA polymerase

18. Transcription Animation

19. DNA vs. RNA Double Stranded Sugar: Deoxyribose Bases: A T C G Location: Nucleus Single strand Sugar: Ribose Bases: A U C G Location: Nucleus & Cytoplasm

20. http://www.youtube.com/watch?v=zwibgNGe4aY

22. DNA and Translation Gene: section of DNA that creates a specific protein –Approx 25,000 human genes Proteins are used to build cells and tissue Protein synthesis involves two processes: 1) Transcription 2) Translation

23. Transcription takes place in the nucleus –1) DNA double helix is broken apart –2) mRNA nucleotides match up –3) Finished mRNA detaches, and moves to a ribosome

24. Codon: Combination of 3 mRNA nucleotides Each mRNA codon matches with 1 of 20 amino acids Ribosome reads codons 1 at a time AUG codon: Activates the ribosome (start codon) UAA or UAG or UGA codon: deactivates the ribosome (stop codon)

25. Defined: Process of making proteins –Step 1: mRNA enters ribosome –Step 2: Ribosome reads one mRNA codon at a time –Step 3: tRNA delivers amino acids until a protein is created

26. Translation Details Translation begins when the mRNA codon “AUG” is read by a ribosome Ribosome reads one codon at a time AUG = methionine GCU = alanine tRNA carries over the proper amino acid –tRNA anticodon matches with the mRNA codon –Prevents delivery of wrong amino acid One by one, amino acids are linked together Translation ends when a “stop” codon is reached What just happened?: A ribosome made a protein

27. Because the codon and anticodon don’t match, the wrong amino acid will not be delivered. This is why the anticodon is important! Now the codon and anticodon match. This ensures the proper amino acid (serine) is delivered.

28. GAU AUG CCG AGU CCA GGA UCU UGA tRNA UAC tRNA GGC tRNA UCA tRNA GGU tRNA CCU tRNA AGA Ribosome Questions to answer: 1)In order, list the amino acids that will be delivered to this ribosome. 2)What is the anticodon of each codon? 3)When finished, how many amino acids in size is this protein? Methionine (MET) Proline (PRO) Serine (SER) Proline (PRO) Glycine (GLY) Serine (SER) ignore tRNA UAC tRNA GGC tRNA UCA tRNA GGU tRNA CCU tRNA AGA startstop

29. Practice Problem DNAmRNA codon tRNA anticodon Amino Acid Always use mRNA to find the amino acid

30. DNAmRNA codon tRNA anticodon Amino Acid Always use mRNA to find the amino acid Practice Problem

31. DNAmRNA codon tRNA anticodon Amino Acid Always use mRNA to find the amino acid glycine CCACCA G G U C C A Practice Problem

32. mRNA Codons Join the Ribosome P Site A Site Large subunit Small subunitmRNA AUGCUACUUCG

33. mRNA AUGCUACUUCG 2-tRNA G Leu AU A 1-tRNA UAC Met codon anticodon

34. 33 mRNA AUGCUACUUCG 1-tRNA2-tRNA UACG Met Leu AU A hydrogen bonds codon peptide bond 3-tRNA GAA Leu

35. mRNA AUGCUACUUCG 1-tRNA 2-tRNA UAC G Met Leu AU A peptide bond 3-tRNA GAA Leu Ribosomes move over one codon (leaves)

36. mRNA AUGCUACUUCG 2-tRNA G Met Leu AU A peptide bonds 3-tRNA GAA Leu 4-tRNA GCU Arg ACU

37. 36 mRNA AUGCUACUUCG 2-tRNA G Met Leu AU A peptide bonds 3-tRNA GAA Leu 4-tRNA GCU Arg ACU (leaves) Ribosomes move over one codon

38. mRNA GCUACUUCG Met Leu A peptide bonds 3-tRNA GAA Leu 4-tRNA GCU Arg ACU UGA 5-tRNA Thr

39. 38 mRNA GCUACUUCG Met Leu A peptide bonds 3-tRNA GAA Leu 4-tRNA GCU Arg ACU UGA 5-tRNA Thr Ribosomes move over one codon

40. mRNA ACAUGU Met Leu U primarystructure of a protein Leu 200-tRNA Arg UAG Thr CU aa200 aa199 terminator or stop or stop codon codon

42. Defined: Any change in DNA Can happen on: 1.Entire chromosomes (loss or gain of a chromosome) 2.Single Gene (change in a DNA base) Mutations

43. Gene: Point Mutations Defined: one nucleotide is substituted for another Often repaired by spellchecker enzyme May lead to amino acid change –See animation May not lead to any change (Silent Mutation) –Ex: DNA “CCC” is mutated into “CCG” »Same amino acid is created (glycine) DNA mRNA Amino acids

44. Gene: Frame Shift Mutation Defined: insertion/deletion of a nucleotide Entire sequence of DNA/RNA after the mutation is shifted (see animation) Much more serious to the structure/function of the final protein –mRNA sequence may have an early “stop codon” –mRNA sequence may have a late “stop codon” DNA mRNA Amino acids

45. Gene: Frame Shift Mutation DNA mRNA Amino acids

46. Chromosome Mutations Translocation: Chromosome segments combine with nonhomologous chromosome Many genes wind up on entirely different chromosomes Gene cut apart –½ on chr #5, ½ on chr #8

47. This is still Down’s Syndrome?

48. Impact on Offspring Somatic cell mutations –Affect only the individual –Not passed on to future generations –Ex: Muscle cell mutation Germ cell mutations –Germ cells = the diploid cells that undergo meiosis to make sperm & egg –May be passed to future generations

49. Mutation Causes Mutagen: agents in the environment that can change DNA –Speed up replication process –Break apart nucleotides Ex: UV sunlight breaks hydrogen bond between thymine (T) and adenine (A)