Lysosomes and DNA Replication Vocabulary

Lysosomes, Organelle Interactions, and Hydrolytic Function

  • Definition and Structure of Lysosomes:

    • Lysosomes are specialized, membrane-bound cellular vesicles that store hydrolytic enzymes.

  • Substrate Targets and Enzymatic Degradation:

    • The hydrolytic enzymes stored inside lysosomes function to break down and degrade four primary classes of biological macromolecules:

    • Proteins

    • Nucleic acids

    • Lipids

    • Carbohydrates

  • Biosynthetic Pathway and Maturation:

    • Hydrolytic enzymes are synthesized and initially formed in the endoplasmic reticulum.

    • Transport vesicles carry these enzymes from the endoplasmic reticulum to the Golgi apparatus.

    • The Golgi apparatus carries out important essential functions in processing these enzymes.

    • Lysosomes officially arise directly from the Golgi apparatus.

  • Phagocytosis and Ingested Particle Processing:

    • White blood cells perform cytocytosis and phagocytosis to internalize particulate matter.

    • Foreign particles ingested via phagocytosis include:

    • Viruses

    • Bacteria

    • Ingestion of a foreign particle forms a membrane-enclosed structure called a phagosome.

    • To degrade the engulfed material, the lysosome fuses directly with the phagosome and delivers its hydrolytic enzymes into the vesicle.

  • Organelle Degradation and Cellular Recycling:

    • Lysosomes fuse with aged or obsolete internal cellular structures, such as old mitochondria.

    • This fusion leads directly to the destruction of the old organelle and the recycling of its constituent biological components.

DNA Replication and Ligation of Okazaki Fragments

  • Storage and Replication of Genetic Information:

    • Genetic information is stored within chromosomes and must be copied accurately.

  • Okazaki Fragment Joining:

    • During the copying of chromosomal information, discontinuous DNA segments known as Okazaki fragments are created.

    • Synthesis alone cannot finish connecting these Okazaki fragments.

    • An enzyme named DNA ligase joins the individual Okazaki fragments together to form a continuous DNA strand.