Here's why:
* Membranous organelles are enclosed by a lipid bilayer membrane, like the nucleus, mitochondria, and endoplasmic reticulum.
* Non-membranous organelles lack a membrane and are directly in contact with the cytoplasm.
Ribosomes are responsible for protein synthesis and are found in both prokaryotic and eukaryotic cells. They are made up of ribosomal RNA (rRNA) and proteins, but they don't have a surrounding membrane.
Other examples of non-membranous organelles include:
* Centrioles: Involved in cell division.
* Microtubules: Provide structural support and act as tracks for movement within the cell.
* Microfilaments: Involved in cell shape and movement.
* Intermediate filaments: Provide structural support and help maintain cell shape.
