2.4 Ribosomal RNA

• What is the third type of RNA in the cell?

  Ribosomal RNA
• What percentage of the ribosome is ribosomal RNA?

  About 60 percent
• What constitutes the remainder of the ribosome?

  Protein
• How many types of proteins are included in the ribosome?

  About 75 types
• What roles do the proteins in the ribosome serve?

  Structural proteins and enzymes
• Where is the ribosome located in the cell?

  In the cytoplasm
• What is the primary function of the ribosome?

  Synthesize protein molecules
• Which two types of RNA does the ribosome function with?

  tRNA and mRNA
• What is the role of tRNA in protein synthesis?

  Transport amino acids to the ribosome
• What does mRNA provide for protein synthesis?

  Information for sequencing amino acids
• How does the ribosome function in protein synthesis?

  Acts as a manufacturing plant for proteins
• Where are the DNA genes for ribosomal RNA located?

  In the nucleus
• How many pairs of chromosomes contain the genes for ribosomal RNA?

  Five pairs
• Why are there many duplicates of ribosomal RNA genes?

  Large amounts of ribosomal RNA are required
• What happens to ribosomal RNA as it forms?

  It collects in the nucleolus
• What is the nucleolus?

  A specialized structure adjacent to chromosomes
• How does the size of the nucleolus change?

  It enlarges with high ribosomal RNA synthesis
• What occurs in the nucleolus regarding ribosomal RNA?

  It binds with ribosomal proteins to form subunits
• What are the granular condensation products formed in the nucleolus?

  Primordial subunits of ribosomes
• How are ribosomal subunits transported after formation?

  Through large pores of the nuclear envelope
• Where are mature ribosomes assembled?

  In the cytoplasm
• Why are proteins not formed in the nucleus?

  The nucleus does not contain mature ribosomes
• What is the process of ribosomal RNA formation and ribosome assembly?

  • Ribosomal RNA is synthesized in the nucleolus.
  • It binds with ribosomal proteins to form subunits.
  • Subunits are transported through nuclear pores.
  • Mature ribosomes are assembled in the cytoplasm.