ribosomes

halpful presantation of ribosomes

1. RIBOSOME SUBMITTED TO Dr. R P SINGH SUBMITTED BY Pandya Dilipbhai k CUG/2014/1078

2. Introduction It is a large & complex molecule. Found in all living cells prokaryote & eukaryote. That serves as the primary site of biological protein synthesis. Ribosome was first observed in 1953s by romanian cell biologist george emil palade using a electrone microscope.

3. george emil palade (1953 )

4. In prokaryote free form in cytoplasm & protoplasm In eukaryote free in cytoplasm inside the cell attach to the outer membrane in endoplasmic reticulum

5. STRUCTURE It is without cell membrane. Two subunits are attach by a different angles. Large subunit Small subunit The subunits of the ribosome are synthesized by the nucleolus.

6. The subunits of ribosomes join together when the ribosomes attaches to the messenger RNA during the process of protein synthesis.  Ribosomes along with a transfer RNA molecule ( tRNA ), helps to translate the protein-coding genes in mRNA to proteins.

7. Ribosome Function Ribosome basically a protein factory. Subunits each have role in making of proteins To understand exactly what each subunit does, it’s necessary to walk through protein synthesis step by step

8. Protein synthesis Process starts from DNA through “transcription” “Translation” is where ribosome comes in. Translation occurs when protein formed from code on mRNA Ribosome carries out the translation of the nucleotide triplets

9. Protein synthesis Chart - visual image of transcription and translation in protein synthesizing DNA and RNA have nucleotides that determine kind of protein 3 nucleotides = 1 amino acid of a protein

10. Ribosome and RNA mRNA with code for proteins located at 30S subunit tRNAs responsible for carrying amino acids to mRNA. Each tRNA has own nucleotide triplet which binds to matching triplet on mRNA, ex., tRNA with code AAA (triple adenine) would match up with mRNA that has code UUU (triple uracil)

11. Initiation: The first phase of translation Translation begins when mRNA attaches to the 30S tRNA comes and binds to mRNA where nucleotide code matches This triggers 50S binding to 30S. 50S is where all tRNAs will bind. Now we move on to elongation

12. Elongation: The second phase Two binding sites on 50S: A site and P site, which aid in continuing translation First tRNA connected at A site. Now moves to P site as another tRNA approaches Second tRNA binds to A site

13. Elongation (continued) Peptide bond forms between amino acids of tRNAs (methionine and proline ) First tRNA now detached from its amino acid, and it leaves ribosome. Second tRNA still has proline and methionine attached

14. Elongation (continued) The tRNA left now moves to P site. Ribosome ready to accept another tRNA and continue process Each tRNA adds another amino acid to growing peptide chain (thus “elongation”) Eventually process has to finish, however

15. End of translation Ribosome was moving along nucleotide triplets one by one Ribosome reaches “stop codon,” peptide chain finished. Last tRNA leaves ribosome, leaving behind completed peptide

16. End of translation (continued) Ribosome separates from mRNA Ribosome subunits also separate, and will remain this way until another mRNA comes along to restart the process