Useful for B. Sc. Botany Syllabus of Dr. Babasaheb Ambedkar Marathwada University

1. Molecular Biology: RNA-Structure, types
and functions
B. Sc. III
Dr. A. S. Naik

2. Complementary m-RNA formation

3. Protein
synthesis
overview.

4. Protein
synthesis
overview-
Role of
different RNAs

5. DNA and RNA

8. mRNA

9. mRNA Regions

10. Details of mRNA regions
• Cap region: Bocked methylated region. Decides rate of protein synthesis. Without cap region, mRNA-
Ribosome bonding is poor.
• NCR-I: 10-100 nucleotides long. Rich in A and U residues. Does not translate into proteins.
• Initiation codon: AUG coding for methionine.
• Coding region: only exons. About 1500 nucleotides in length. Codes for proteins.
• Termination codon: UAA/ UAG/ UGA- stop codons. Terminate protein synthesis.
• NCR-II: 50-150 nucleotides long. Does not translate into proteins.
• Poly-A Sequence: Polyadenylate sequence, at 3’ end, initially 200-250 nucleotides short, becomes shorter
with age. Added in nucleus prior to exit.
• mRNA combines with ribosomes to form polysomes.
• It is constantly undergoing breakdown, not stable in prokaryotic cells hence unstable, unlike
eukaryotic cells.

11. tRNA

12. tRNA structural details: Loops+stems=arms
• Accepter arm: -CCA sequence at 3’ end. 7 base pairs in stem and 4 unpaired bases in the loop. Also-Amino
acid binding site.
• D-Arm: 15-18 nucleotides, 3-4 pairs in arm, 7-11 unpaired bases in loop. Dehydrouridine (DHU) loop/D-
loop. Recognises with Synthetase site for recognizing Amino acid located on it.
• Anticodon arm: Anticodon stem of 5 base pairs in stem and 7 unpaired bases in the loop. Reads Base
sequence of codons on mRNA and binds with it. This arm has complimentary base sequence to mRNA,
• Variable Arm: Miniloop/ Lump/ Loop-III. May be of 2 types.
• T phi C Arm: Stem with 5 bp and loop of 7 unpired bases.. It is ribosome recognition site.

14. Different types of RNAs- comparison

16. Structural Details of rRNA

17. rRNA

18. Protein synthesis

19. PROTEIN SYNTHESIS