Cell Organelles: Ribosomes and Endoplasmic Reticulum

Overview of Organelles in Eukaryotic Cells

• Focus on two critical organelles:

  • Ribosomes

  • Endoplasmic Reticulum (ER)

• Ribosomes are found in both eukaryotic and prokaryotic cells.

Ribosomes

• Structure and Function:

  • Small, circular structures within the cell.

  • Primary function: Produce proteins.

• Protein Synthesis Process:

  • Ribosomes follow instructions from DNA, housed in the nucleus.

  • Transmit a snippet of information known as mRNA (messenger RNA), which corresponds to one gene.

  • Changes in the code of mRNA can alter the protein produced, which may affect the organism's functioning.

• Ribosome Types:

  • Free Ribosomes:

    • Scattered throughout the cytoplasm.

    • Produce proteins that function in the cytoplasm.

    • Example: High concentration in pancreatic cells which synthesize digestive enzymes.

  • Attached Ribosomes (Rough ER):

    • Ribosomes bound to the endoplasmic reticulum (ER).

    • Produce proteins meant for transport, as the rough ER is a network for material movement.

    • Under a microscope, rough ER looks "rough" due to ribosomes on its surface.

    • In addition to protein synthesis, rough ER synthesizes and produces more membrane material.

Endoplasmic Reticulum (ER)

• Types of Endoplasmic Reticulum:

  • Rough ER:

    • Contains ribosomes on its surface.

    • Responsible for protein synthesis and additional membrane production.

  • Smooth ER:

    • Lacks ribosomes, hence appears smooth under a microscope.

    • Functions include:

      • Synthesizing lipids, which are necessary for cell membranes.

      • Producing steroids and hormones (a specific type of lipid).

      • Detoxifying various substances, including drugs and toxins.

    • High presence in liver cells for detoxification purposes.

• Liver Health:

  • Continuous use of the liver for detoxification may lead to premature aging and wear-out of the organ.

  • Both legal and illegal substances, including medications, can accelerate liver fatigue.

Summary of Key Points

• Ribosomes act as protein factories guided by DNA instructions via mRNA.

• Rough ER, with attached ribosomes, is involved in protein synthesis and membrane production.

• Smooth ER is responsible for lipid synthesis and detoxification processes, predominantly in liver cells.