Ribosome ppt (introduction structure & Function)

cell organelle ribosome ppt presented in American University of Barbados.

1. Ribosome Yogesh Vishwakarma Jay Patel

2. Introduction Cell’s factory; site for protein synthesis (Translation) Also know as Translational Apparatus Non-membranous organelle Mostly attached to Rough ER Also found free Made up of rRNA and ribosomal proteins

3. How did we know about it? First observed during mid 1950s by George Emil Palade By electron microscope as dense particles First named Microsomal Particles Its detailed structure was discovered in 2000 and 2001

4. Types of Ribosome Classified according to their location Membrane-Bound Ribosomes Synthesize proteins for membranes and exocytosis (Used outside the cell) Attached to ER and other organelles Free Ribosomes Found freely in cytoplasm (Red arrows) Synthesize proteins that function inside the cytosol (Used inside the cell e.g. food metabolism)

5. Structure and Composition Made up of rRNAs and distinct Ribosomal Proteins 3 (Prokaryotic) or 4 ( Eukaryotic) rRNAs And 40 to 80 different proteins Arranged into two pieces while Translation Small ribosomal subunit (30s) Large ribosomal subunit (50s)

6. Large Subunit Contains the active site of ribosome The site where new peptide bonds are formed (Green) Contains Aminoacyl binding site Contains Peptidyl binding site It uses peptidyl transferase to catalyze the process(Green) Made of two rRNA strands (Yellow and Orange) And many protein strands (Blue)

7. Small Subunit In charge of information flow Pairing codons with anti-codons Intake of mRNA mRNA enters through the opening in the left side Made of rRNA (Orange) And protein strands (Blue) Contains the entry and exit sites of mRNA

8. Ribosome Biogenesis It is the process of making Ribosomes in the nucleus The protein parts are made in the cytoplasm (Ribosome) Then transferred to the nucleus (Nuclear Pores) rRNAs are transcribed in the nucleolus The ribosomal proteins and rRNAs bind together Small and large subunits are made They are transported out of nucleus (Pores)

9. Function The one and only function is Protein Synthesis This process is called Translation Begins with transcription of mRNA in the nucleus mRNA travels to the cytoplasm with specific codes It binds with the small subunit of the ribosome The two subunits come together

10. Continued tRNAs transfer amino acids to the ribosome Translation is started by AUG codon Starting amino acid is methionine Amino acids are attached in the active site to form peptide chains Synthesis is stopped when a stop codon comes (UAA, UGA UAG) The chain exits through the exit tunnel into cytoplasm or ER

11. Functional Requirements A secure site for operation Formed by binding of two subunits A supply of information or blueprints Supplied by nucleus through mRNA A supply of amino acids to build from Transferred by tRNA, acquired from food Means of releasing it into cytoplasm Exits through the exit tunnel or cleft (Large subunit)

12. Reaction to Anti-Biotics Several anti-biotics work by inhibiting synthesis of prokaryotic ribosomes Some antibiotics such as Streptomycin inhibit the small subunit While other antibiotics such as Erythromycin inhibit the large subunit Antibiotics may not affect eukaryotic cell ribosomes

13. Common Disorders Most of the disorders associated with ribosome have abnormal biogenesis It is the abnormal formation of ribosomes Mostly they get destroyed but they escape in rare cases Some major diseases caused by abnormal ribosome; Diamond- Blackfan anemia Treacher Collins syndrome Cartilage-hair hypoplasia

14. Keep your factory safe

15. Questions

16. References https://en.wikipedia.org/wiki/Ribosome#Discovery https://bscb.org/learning-resources/softcell-e-learning/ribosome/ http://pdb101.rcsb.org/motm/10 https://micro.magnet.fsu.edu/cells/ribosomes/ribosomes.html https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2858486/ Cell Biology & Histology, Gartner L.P., Hiatt J.L., 7 th Edition Essential Cell Biology, Alberts, Bray, Hopkins, Lewis, 4 th Edition

17. Hope you learned something, Thank You!