biology notes

  ➤➤➤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 ...