1. Molecular Genetics
Prof. Haim Cohen, 8383, Nano Bldg Room 804A
Today we will discuss about DNA and the concept of mutations, complementation and complementation groups

2. Molecular Genetics First step: DNA is the genetic material
DNA, NOT protein of the chromosomes/chromatin
PROVEN WITH TRANSFORMATION AND TRANSDUCTION, THAT WE JUST MASTERED

5. Mutation
First, conceptual basis of the connection between mutation (Gene, or DNA change), and phenotype

6. Neurospora crassa

7. Neurospora crassa

8. גיבורים

9. One gene one enzyme hypothesis
One gene one enzyme hypothesis. The first exciting insight into the function of genes

10. One gene one enzyme hypothesis
One gene one enzyme hypothesis. The first exciting insight into the function of genes

11. One gene one enzyme hypothesis
One gene one enzyme hypothesis. The first exciting insight into the function of genes

12. One gene one enzyme hypothesis
One gene one enzyme hypothesis. The first exciting insight into the function of genes

14. x x x Gene1 Gene2 Gene3 Precursor X Y Z
One gene one enzyme hypothesis. The first exciting insight into the function of genes
Mutant
Ornithine
Citruline
Arginine
arg-1
arg-2
arg-3
Supplement x x x
Gene1
Gene2
Gene3
Precursor X Y Z
Precursor ornithine citruline arginine
ARG1
ARG2
ARG3

16. In bacteria - Introduce an isolated (cloned) gene by transformation
In vitro
NOT like above, where the DNA must recombine and replace the endogenous copy,
BUT where the DNA is extrachromosomal and persists as an episome (plasmid, F’, etc.)

17. Complementation assays
r 1 X r2 ?

18. Complementation assays
r 1 X r2 ?
Wild-type (WT)

24. gtg cat ctg act cct gag gag
One gene – one gene product (here a protein)
From gene to gene product function, from mutation to phenotype
gtg cat ctg act cct gag gag
Peptide bond

28. A single b.p. change in the hemoglobin gene leads
to all the phenotypes of Sickle Cell Anemia

29. gtg cat ctg act cct gag gag
From gene to gene product function, from mutation to phenotype
gtg cat ctg act cct g t g gag
MUTANT –Sickle cell anemia
gtg cat ctg act cct g t g gag

30. wild type
Hemoglobin-S sickle cell

33. From gene to gene product function, from mutation to phenotype

34. gtg cat ctg act cct gag gag
gene ->gene product function, mutation to phenotype,
In bacterial enzyme, or in gene for complex Human syndrome
gtg cat ctg act cct gug gag
MUTANT –Sickle cell anemia
אנמיה חרמשית
gtg cat ctg act cct gug gag

35. Xeroderma pigmentosum

36. המופיליה B חוסר ב- Factor IX
חוסר ב-
Factor IX
Simple (even spontaneous) changes, huge consequences – how to find them?

37. Gene for
Factor IX
(HemoB)
Factor IX
(HemoB)

38. Phenotypic
Rescue:
Introduce an
isolated (cloned)
gene by viral
(engineered)
Infection with
Hemo.B gene
(encodes clotting
Factor IX).

39. Evolution from “1 gene, 1 protein” to…
Haemoglobin
1 gene, 1 polypeptide
1 gene, 1 gene product
tRNAs, rRNAs, snRNAs, miRNAs, …
Additionally – next: (e.g. for proteins)- many sites are
susceptible to mutations outside of coding region

40. Genes contain much more information than the structural region
(or "coding region for proteins") of the gene product.
They include information directing the proper timing and placement of the
expression of the gene product

41. Regulatory
Coding

42. Coding
Promoter

43. Transcriptional controls on initiation, elongation, termination of RNA
Example: Prokaryotes and Eukaryotes have highly conserved necessary promoter
elements specific distances from transcription start, enhancers which act from varying
distances.
Specifically: many eukaryotic genes have a "TATA box" 30 bases from the start site and a CCAAT box base pairs from the start site in their promoter.

45. Translational controls on initiation, elongation, termination, localization
Example: Here too, a large degree of control is exercised at initiation, and the "non-translated leader" portion of RNA includes control information.
Starts are always at Met (AUG), but specifically, in Prokaryotes: true start sites are preceded by a consensus sequence know as a ribosome binding site, or Shine - Dalgarno sequence - AGGAGGU (prok.)

46. Ribosome
Binding site

48. Animation ch-9 transl…nSteps TRANSLATION/Shine-Dalgarno

49. Shine-Delgarno

50. Example: Eukaryotic RNA's are spliced - one of several post
Post transcriptional modifications of the RNAs
Example: Eukaryotic RNA's are spliced - one of several post
transcriptional alterations

51. Splicing site

53. Polyaden.
site

57. Post-translational modifications, processing, packaging and trafficking of proteins

59. Mutation are the driving force of nature