WHAT ARE RIBOSOMES???

 ➤➤➤RIBOSOMES➤➤➤

 

➤DISCOVERED BY;

★IN 1955, GEORGE EMIL PALADE WAS THE FIRST PERSON WHO STUDY THE 

  RIBOSOME, USING ELECTRON MICROSCOPE.

➤DEFINITION;

★CELL CONTAINS MANY TINY GRANULAR STRUCTURES KNOWN AS 

   "RIBOSOMES."

➤EUKARYOTIC RIBOSOME;

★EUKARYOTIC RIBOSOMES ARE COMPOSED OF AN ALMOST EQUAL  

   AMOUNT OF RNA AND PROTEIN,

  HENCE THEY ARE RIBONUCLEOPROTEINS PARTICLES. 

➤RIBOSOMAL RNA; (rRNA)

★THE RNA PRESENT IN RIBOSOME IS CALLED RIBOSOMAL RNA.

➤FORMS OF RIBOSOME;

 ★RIBOSOMES EXIST IN TWO FORMS; 

  "EITHER FREELY DISPERSED IN CYTOPLASM OR ATTACHED WITH RER AS TINY

  GRANULES."

➤SUBUNITS;

★EACH EUKARYOTIC RIBOSOME CONSISTS OF TWO SUB-UNITS. 

LARGER SUBUNIT;

★THE LARGER SUBUNIT SEDIMENTS AT 60S.

 (S=SVEDBERG UNIT USED IN ULTRACENTRIFUGATION).

SMALLER SUBUNIT;

★WHILE SMALLER SUBUNIT SEDIMENTS AT 40S. 

  THE RIBOSOMES ARE ATTACHED TO MESSENGER RNA THROUGH SMALL 

  RIBOSOMAL SUBUNIT. 

FORMATION OF 80S PARTICLE;

★TWO SUBUNITS ON ATTACHMENT WITH EACH OTHER FORM 

  80S PARTICLE. 

➤CONTROLLED BY;

★THIS ATTACHMENT IS CONTROLLED BY THE PRESENCE OF 

   MG2+ IONS. 

➤POLYSOME;

 ★A GROUP OF RIBOSOMES ATTACHED TO mRNA IS KNOWN AS POLYSOME. 

➤ASSEMBLING OF NEW RIBOSOME;

★NEW RIBOSOMES ARE ASSEMBLED IN THE NUCLEOLUS OF THE NUCLEUS

   FROM WHERE THEY ARE TRANSPORTED TO THE CYTOPLASM VIA THE

  PORES IN NUCLEAR MEMBRANE. 

➤FACTORY OF RIBOSOME;

★THE FACTORY OF RIBOSOME IS THE NUCLEOLUS, WHILE THAT OF 

  PROTEIN SYNTHESIS IS THE RIBOSOMES.

THE END