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Organelles in eukaryotic cells | The cellular basis of life | High school biology | Khan Academy

Introduction to Eukaryotic Cells

  • Eukaryotic cells contain membrane-bound organelles.

  • Membrane-bound organelles serve as sub-compartments within the cell.

Cellular Structure

  • Cell Membrane: Encloses the cell, contributing to its shape and three-dimensional structure.

  • Genetic Information: Most cells contain genetic info in the form of DNA.

    • In eukaryotic cells, DNA is housed in a membrane-bound organelle known as the nucleus.

Key Membrane-Bound Organelles

Nucleus

  • Surrounded by the nuclear membrane.

  • Contains pores that connect to the endoplasmic reticulum (ER).

Endoplasmic Reticulum (ER)

  • Comprised of layers of membranes that extend from nuclear pores.

    • Rough Endoplasmic Reticulum (RER): Studded with ribosomes; involved in protein synthesis.

    • Smooth Endoplasmic Reticulum (SER): Lacks ribosomes; involved in lipid synthesis and detoxification processes.

Ribosomes

  • Sites of protein synthesis, translating mRNA into proteins.

    • Free Ribosomes: Floating in cytoplasm; produce proteins for use within the cell.

    • Bound Ribosomes: Attached to the rough ER; produce proteins meant for secretion or for use in the cell membrane.

Golgi Apparatus/Bodies

  • Functions to package and modify molecules, especially proteins produced by the ER.

    • Complexes proteins into vesicles for transport outside the cell.

Mitochondria

  • Known as the powerhouse of the cell.

  • Responsible for ATP production through cellular respiration.

  • Contains its own DNA, which is inherited maternally.

  • Believed to have originated from independent prokaryotic cells that entered into symbiosis with ancestral eukaryotic cells.

Chloroplasts (in plant cells)

  • Sites of photosynthesis, converting sunlight into chemical energy.

  • Contain thylakoid stacks where chlorophyll is located.

Vacuoles

  • Large storage organelles, prominent in plant cells.

    • Serve as storage compartments for water, enzymes, and other substances.

    • Help maintain cell structure and turgor pressure in plants.

Lysosomes

  • Contain enzymes that break down waste materials and cellular debris.

  • Important for recycling cellular components and digesting foreign substances.

Complexity of Eukaryotic Cells

  • Eukaryotic cells are incredibly complex, housing numerous organelles with specialized functions.

  • This includes various structures that facilitate transport, movement, and replication within the cell.

  • Cells can be likened to bustling cities, with constant activities and processes happening simultaneously.