EXPRESSION OF BIOLOGICAL INFORMATION

EXPRESSION OF BIOLOGICAL INFORMATION

1. MUTATION

   • Any changes in genes or chromosomes
     • spontaneous changes
     • induced changes
   • eg. point mutation, frameshift mutations, missense mutation, nonsense mutation

2. SYNDROMES

   • gene mutation
     • eg.: sickle cell anemia, thalassemia major, cystic fibrosis
   • chromosomal mutation
     • chromosomal aberration, chromosomal number alteration
       • sex chromosomes
         • eg: Klinefelter's syndrome, XYY syndrome, XXX syndrome
       • Autosome
         • eg: Down's syndrome, trisomy- 13, trisomy- 18

3. DNA

   • Frederick Griffith (1928)
     • Griffith experiment: genetic role of DNA
   • Avery, MacLeod, and McCarty' experiment (1952)
     • worked in transforming harmless bacteria into pathogenic bacteria
   • Hershey and Chase (1952)
     • Molecular basis of inheritance

4. STRUCTURE OF DNA

   • The Double Helix
     • Semiconservative model
     • X-ray cystallography
   • Complementary Stands
     • two structure follow lock and key principle
   • Chargaff's Rule
     • NO. of bases are equal A=T, G=C

5. DNA Replication

   • Helicase Unwinds
     • Single-strand binding protein stabilizes
       • DNA polymerase iii synthesizes leading strand
         • lagging strand synthesized discontinously. Primase synthesizes RNA primer which is extended by DNA polymerase III to form an Okazaki fragment.
           • RNA primer replaced by DNA ( DNA polymerase I) and DNA ligase joins the Okazaki fragment to the growing strand.

6. GENE EXPRESSION

   • Transcription
     • DNA to mRNA
   • Translation
     • RNA to protein

7. OPERON

   • entire stretch of DNA (operator, promoter and genes they control)
     • Repressible Operon
       • regulated by the presence of metabolic end product ( co-repressor, tryptophan)
     • Inducible Operon
       • Regulated by substrate present in the metabolic pathway. (inducer, allo lactose)
       • eg: Lactose Operon (Lac operon)
         • only when lactose is present and glucose is absent