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Molecular Genetics

Molecular Genetics. PaCES Summer Program in Environmental Science. What is Molecular Genetics?. Molecular Genetics is is the field of biology that studies the structure and function of genes at a molecular level. nitrogenous base. phosphate. pentose sugar. Nucleotides. Pentose Sugars.

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Molecular Genetics

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  1. Molecular Genetics PaCES Summer Program in Environmental Science

  2. What is Molecular Genetics?

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

  4. nitrogenous base phosphate pentose sugar Nucleotides

  5. Pentose Sugars

  6. Nucleotides Bases Purines: two carbon rings

  7. Nucleotides Bases Pyrimidines: single carbon rings

  8. 3’ carbon 5’ carbon Polymerization of Nucleotides

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

  10. The Double Helix

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

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

  13. DNA Replication

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

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

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

  17. DNA polymerase III RNA primer 5´ end 3´ end 3´ end 5´ end new complimentary DNA DNA Replication

  18. newest DNA 5´ end 3´ end 3´ end 5´ end DNA polymerase I DNA Replication

  19. new complimentary DNA 5´ end 3´ end 3´ end 5´ end parent DNA template DNA Replication

  20. PCR: Amplification of DNA

  21. Where's my DNA?

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

  23. 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

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

  25. Steps of Gene Expression Transcription Translation

  26. Transcription and Translation DNA Transcription mRNA protein Translation

  27. Decoding DNA • The first step of decoding the genetic message is to copy the nucleotide sequencefromDNAtoRNA

  28. 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 URACILinstead of THYMINE

  29. 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

  30. 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

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

  32. Ribosome large subunit functional ribosome small subunit

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

  34. Structure of tRNA

  35. 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

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

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

  38. Base Pairing in DNA

  39. Base Pairing in RNA

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

  41. Transcription

  42. 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

  43. Translation

  44. 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)

  45. 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

  46. Codon Chart Start Codon

  47. Codon Chart

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

  49. 5’ 3’ Translation

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