1. DNA and the Language of Life
Chapter 12
DNA and the Language of Life

2. DNA: The Genetic Material

3. How do we know that DNA is the genetic material?
Essential Question
How do we know that DNA is the genetic material?

4. 1928 - Key Player Identified the “Transforming Factor”
Frederick Griffith

5. Griffith's "Transforming Factor" Is the Genetic Material

6. 1944 DNA Identified as “The Transforming Factor”
Oswald Avery Colin MacLeod Maclyn McCarty

7. Isolated genetic material in vitro.
DNA from S strain causes R strain to be transformed
Proteases cannot prevent transformation
RNase cannot prevent transformation
Molecular weight is large
DNase destroyed all transforming activity

8. 1950 - Erwin Chargaff Chargaff’s Rules
Proportion of A = that of T and G=C
Equal proportions of A and G and C and T

9. 1952 More Evidence of DNA & Heredity Martha Chase & Alfred Hershey

10. Virus Experiments of Hershey & Chase Provide More Evidence

12. 1953 - DNA Structure Determined James Watson & Francis Crick

13. Structure of DNA

14. Key Players
Rosalind Franklin
Maurice Wilkins

15. X-ray Crystallography of DNA
Photo 51

16. Nucleic Acids Store Information

17. Nucleotide

19. The DNA Molecule is antiparallel.

20. Nucleotide monomers join together by covalent bonds between the sugar of one nucleotide and the phosphate of the next, forming a sugar-phosphate backbone.

21. DNA contains four different nitrogenous bases
DNA contains four different nitrogenous bases. Thymine and cytosine have single-ring structures. Adenine and guanine have double-ring structures.
                                                                                                                                                                                                                          

22. Remembering which are which!
Angels of God are PURe.
A(ngels) = Adenine
G(od) = Guanine
PUR(e) = Pur(ines)

23. Numbers of Hydrogen Bonds
A-T have two
but
G-C have three

24. Section 12.2 DNA Replication The Molecular Mechanism of Inheritance

25. DNA Replication Occurs before cell division (S-phase)
Each daughter molecule has one old strand (derived or “conserved” from the parent molecule) and one newly made strand.

26. DNA Replication is SemiconservativeG T A A T G C
Parent molecule
Figure 16.9 A model for DNA replication: the basic concept

27. DNA Replication is SemiconservativeG C G T A T A A T A T G C G C
Parent molecule
Separation of strands
Figure 16.9 A model for DNA replication: the basic concept

28. DNA Replication is SemiconservativeG C G C G C G T A T A T A T A A T A T A T A T G C G C G C G C
Parent molecule
Separation of strands
“Daughter” DNA molecules, each consisting of one parental strand and one new strand
Figure 16.9 A model for DNA replication: the basic concept

29. Molecular Genetics
DNA Replication

30. Section 12.3 DNA, RNA and Protein

31. Key Terms
RNA
Transcription
Translation
codon

32. DNA is the universal language of life.
Translate the following statement:
DNA is the universal language of life.

33. Genetic makeup – the sequence of nucleotide bases in DNA.
Genotype
Genetic makeup – the sequence of nucleotide bases in DNA.

34. The Relationship Between Genes and Proteins
1 gene = 1 polypeptide.

35. DNA vs. RNA Double stranded Thymine is one of the bases
Deoxyribose sugar
Single stranded
Uracil instead of Thymine
Ribose sugar

36. From gene to polypeptide.

37. Transcription/Translation Analogy
DNA  RNA (Transcription)
Like transcribing a speech
Language is the same
Form changes (spoken to written)
RNA  Protein (Translation)
Converts nucleic acid language into amino acid language.
Based on codons (3 base word)

38. Molecular Genetics

39. Triplet Code Shared by almost all organisms
61 of the triplets code for amino acids
Some amino acids are coded for by more than 1 codon.
No codon represents more than 1 amino acid.
3 STOP codons come at end of gene sequence.

40. Triplet Code

41. Triplet Code
Inner circle signifies first nucleotide in codon, second circle signifies second nucleotide in codon, outer circle.

42. Concept 12.5 There are Two Main Steps From Gene to Protein DNA  RNA RNA  Protein

43. Key Terms Messenger RNA (mRNA) Transfer RNA (tRNA)
Ribosomal RNA (rRNA)
Codon
anticodon

44. Transcription (DNA  RNA)
RNA nucleotides base-pair one by one with DNA nucleotides on one of the DNA strands (called the template strand). RNA polymerase links the RNA nucleotides together.

45. In eukaryotes, the RNA transcript is edited before it leaves the nucleus. Introns are removed and the exons are spliced together before the "final draft" transcript moves into the cytoplasm where it gets translated.

46. Translation (RNA  Protein)

47. tRNAs transport and match amino acids to their appropriate codons on the mRNA transcript. One end of the tRNA attaches to an amino acid. At the other end, a triplet of bases called the anticodon matches to the complementary mRNA codon.

48. Ribosomes bring mRNA and tRNAs together during translation
Ribosomes bring mRNA and tRNAs together during translation. Each ribosome has an attachment site for an mRNA transcript, and two sites for tRNAs.

49. Ribosomes

50. Adding Amino Acids to a Polypeptide chain

54. Translation begins with the attachment of a ribosome and the first tRNA to a "start" (AUG) codon. The ribosome then moves along the mRNA transcript. The polypeptide elongates as an amino acid is added for each codon. When the ribosome arrives at a "stop" codon, the completed polypeptide is released.

55. Molecular Genetics

56. Section Gene Mutation

57. Key Terms Mutation - any change in the nucleotide sequence of DNA.
mutagen - Physical or chemical agents that cause mutations.

58. Body-cell v. Sex-cell Mutation
Somatic cell mutations are not passed on to the next generation.
Mutations that occur in sex cells are passed on to the organism’s offspring and will be present in every cell of the offspring.

59. DNA Mutations
Substitutions
Insertions
Deletions

60. DNA Mutations
Insertion or deletion of one or more nucleotides in a gene is usually more disastrous than the effects of a base substitution.

61. Types of DNA Mutations
There are three general categories of gene mutation: base substitutions, insertions, or deletions.

62. THE BIG FAT CAT ATE THE WET RAT
DNA Mutations
THE BIG FAT CAT ATE THE WET RAT
Normal
THE BIG FAT CAT ATE THE WET RAT

63. THE BIZ FAT CAT ATE THE WET RAT
DNA Mutations
THE BIG FAT CAT ATE THE WET RAT
Substitution
THE BIZ FAT CAT ATE THE WET RAT

64. DNA Mutations THE BIG FAT CAT ATE THE WET RAT Insertion
(causing frameshift)
THE BIG ZFA TCA TAT ETH EWE TRA

65. THB IGF ATC ATA TET HEW ETR AT
DNA Mutations
THE BIG FAT CAT ATE THE WET RAT
Deletion
(causing frameshift)
THB IGF ATC ATA TET HEW ETR AT

66. THE BIG FAT FAT ATE THE WET RAT
DNA Mutations
THE BIG FAT CAT ATE THE WET RAT
Duplication
THE BIG FAT FAT ATE THE WET RAT
Fragile X Syndrome

67. Common Mutagens
Most common: high-energy radiation (X-rays and ultraviolet light)
Chemical mutagen: chemicals that are similar to normal DNA bases but cause incorrect base-pairing when incorporated into DNA.
A mutation present in a gamete can be passed on to its offspring.