1. NATURE OF GENETIC MATERIALS
Dr. Vinod K.V.

2. Composition and structure of Nucleic acids
DNA- Deoxyribo Nucleic acid Isolated by Friedrich Miescher (1869) & called nuclein Polymer of nucleotides- polynucleotides Nucleotide= pentose sugar+NB+phosphate group

5. Chargaff’s rule (Erwin Chargaff 1940)
1. DNA contains equal amounts of purines & pyramidines
A+G = C+T
Amount of Adenine is equal to that of Thymine & Guanine is equal to cytosine
A=T & G=C

8. RNA (Ribo Nucleic Acid)
Sugar is ribose
NB uracil is present instead of Thymine
Single stranded
Not self duplicating (except viral)

9. Three types m RNA- messenger RNA r RNA- ribosomal RNA
t RNA- transfer RNA
Produced from DNA template strand by RNA polymerase enzyme
Prokaryotes- single RNA polymerase
Eukaryotes- I - r RNA, II – mRNA, III- t RNA

10. m RNA Carry information as triplet codon for polypeptide production
Triplet codon- 3 continuous nucleotides code for an amino acid
Leader region is 5’ end
Carry initiation codon (to start translation) & termination codon (for termination)

11. rRNA Are structural components of ribosomes
Undergo folding & coiling & interact with ribosomal proteins to form subunits
In prokaryotes- 5S, 16S, 23S rRNAs
5& 23 S are components of large subunit (50S)
16 S- small subunit (30S)
In eukaryotes- 5S, 5.8S, 18S, 28S
5, 5.8, 28 S- large subunit (60S)
18S- small subunit (40S)

12. tRNA Transfer of aminoacids from cytoplasm to ribosomes
Ranges in size from nucleotides
Clover leaf model
5 double helical arms
Acceptor arm
anticodon arm
thymine –puedouracil arm (TΨC arm)
dihydro uridine arm (DHU arm)
& an extra or accessory arm.

13. Acceptor arm In the 3’ terminal Carrying an ACC sequence
where amino acid binds

14. Anticodon arm 5 bp stem & a loop Central 3 nucleotides –
called triplet anticodon-
identify codons in mRNA

15. Thymine –pseudouracil arm
5 bp stem & loop containing G TΨC
Concerned with binding of tRNA with ribosome

16. Dihydro uridine arm 3-4 bp stem & a DHU loop
Helps in recognition of aminoacyl tRNA synthetase enzyme
(Enzyme concerned with recognition & activation of amino acids)

17. L shaped tertiary structure
Clover leaf undergo further folding form L
Acceptor arm & TΨC arm in one direction
DHU arm & anticodon in another

18. Cell also contain sn RNA- small nuclear RNA
sc RNA- small cytoplasmic RNA
RNA i- RNA interface