1. Molecular Genetics PaCES Summer Program in Environmental Science

2. What is Molecular Genetics?

3. Molecular Genetics is is the field of biology that studies the structure and function of genes at a molecular level.

4. Nucleotides pentose sugar phosphate nitrogenous base

5. Pentose Sugars

6. Nucleotides Bases Purines: two carbon rings

7. Nucleotides Bases Pyrimidines: single carbon rings

8. Polymerization of Nucleotides 5’ carbon 3’ carbon

9. Polynucleotides (Nucleic Acids) 5’ end 3’ end

10. The Double Helix

11. Adenine (A) Thymine (T) Base Pairing in DNA

12. Guanine (G) Cytosine (C) Base Pairing in DNA

13. DNA Replication

14. Strand Polarity in Complimentary Strands of Double-Stranded DNA Strand Polarity in DNA

15. Adding Nucleotides Add to 3’ end of new strand (begin at 5’ of template)

16. DNA Replication 3´ end5´ end 3´ end 5´ end parent DNA template RNA primer primase

17. DNA Replication new complimentary DNA RNA primer 3´ end5´ end 3´ end DNA polymerase III

18. DNA Replication 3´ end5´ end 3´ end newest DNA DNA polymerase I

19. DNA Replication 3´ end5´ end 3´ end parent DNA template new complimentary DNA

21. PCR: Amplification of DNA

22. Where's my DNA?

23. DNA (genetic code) Polypeptide or Protein (linear sequence of amino acids) Gene Expression

24. Polypeptides and Proteins Molecules composed of linear arrangements of amino acids It is the sequence of these amino acids that determines the properties of a particular polypeptide or protein Molecules composed of linear arrangements of amino acids It is the sequence of these amino acids that determines the properties of a particular polypeptide or protein

25. Proteins differ according to their order of amino acids TYR GLY SER ALA ILE MET LEU GLN GLY ASP ASN ILE GLN SER GLU HIS Protein 1 Protein 2

26. Steps of Gene Expression Transcription Translation

27. Transcription Translation DNA mRNA protein Transcription and Translation

28. Decoding DNA  The first step of decoding the genetic message is to copy the nucleotide sequence from DNA to RNA

29. RNA Acts like a disposable copy of DNA for making protein Controls the assembly of amino acids into protein Same nucleotides as DNA A single-strand of nucleotides Contains URACIL instead of THYMINE Acts like a disposable copy of DNA for making protein Controls the assembly of amino acids into protein Same nucleotides as DNA A single-strand of nucleotides Contains URACIL instead of THYMINE

30. Types of RNA Three types: Messenger RNA (mRNA) Ribosomal RNA (rRNA) Transfer RNA (tRNA) Each plays a different role in the assembly of amino acids into protein Three types: Messenger RNA (mRNA) Ribosomal RNA (rRNA) Transfer RNA (tRNA) Each plays a different role in the assembly of amino acids into protein

31. mRNA Messenger RNA A direct copy of the DNA but using Uracil Acts as a messenger from the DNA to the rest of the cell Base sequence reflects that of a gene that specifies the amino acid sequence of a protein Messenger RNA A direct copy of the DNA but using Uracil Acts as a messenger from the DNA to the rest of the cell Base sequence reflects that of a gene that specifies the amino acid sequence of a protein

32. rRNA Ribosomal RNA Remember, proteins are assembled ON ribosomes The rRNA is found attached to the ribosomes where the proteins are assembled Ribosomal RNA Remember, proteins are assembled ON ribosomes The rRNA is found attached to the ribosomes where the proteins are assembled

33. Ribosome large subunit small subunit functional ribosome

34. tRNA Transfer RNA A type of RNA that collects the necessary amino acids and escorts them to the assembly site on mRNA Transfer RNA A type of RNA that collects the necessary amino acids and escorts them to the assembly site on mRNA

35. Structure of tRNA

36. Gene Expression: Transcription Involves the copying of the genetic code into a molecule of messenger RNA (mRNA) Only copies the area of interest in DNA strand In the eukaryotic cell, transcription occurs in the nucleus. Prokaryotes don’t have a nucleus. Base pairing rules apply except that uracil replaces thymine in RNA Involves the copying of the genetic code into a molecule of messenger RNA (mRNA) Only copies the area of interest in DNA strand In the eukaryotic cell, transcription occurs in the nucleus. Prokaryotes don’t have a nucleus. Base pairing rules apply except that uracil replaces thymine in RNA

37. RNA DNA RNA polymerase Location: In the Nucleus Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) All of Transcription (making mRNA) in eukaryotes takes places in the nucleus

38. Only unwinds segment that codes for a certain protein RNA Polymerase add complementary bases

39. Base Pairing in DNA

40. Base Pairing in RNA

41.  The mRNA strand turns out the same as Sense Strand, except for U’s instead of T’s

42. Transcription

43. Gene Expression: Translation  Involves reading the triplet codons of the mRNA to determine the sequence of amino acids in a protein  Three stages: initiation, elongation, and termination  Occurs in the cytoplasm of all cells  Involves reading the triplet codons of the mRNA to determine the sequence of amino acids in a protein  Three stages: initiation, elongation, and termination  Occurs in the cytoplasm of all cells

44. Translation

45. The Nature of the Genetic Code A sequence of three consecutive nucleotide bases codes for an amino acid in a protein There are 64 possible combinations of a triplet code that draws from four different letters (bases) A sequence of three consecutive nucleotide bases codes for an amino acid in a protein There are 64 possible combinations of a triplet code that draws from four different letters (bases)

46. Codon There are 20 different possible amino acids to make from different codons. 3 possible stop codon 1 start codon TAC on DNA AUG on RNA There are 20 different possible amino acids to make from different codons. 3 possible stop codon 1 start codon TAC on DNA AUG on RNA

47. Codon Chart Start Codon

48. Codon Chart

49. Amino Acid tRNA mRNA Ribosome Codon Anticodon Translation 5’3’

50. Translation 5’3’

51. Translation 5’3’

52. Translation 5’3’

53. Translation 5’3’

54. Translation 5’3’

55. Translation 5’3’

56. Summary of Transcription and Translation