01.05 Non-Membranous Organelles

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I. Non-membranous Organelles

  1. Ribosomes
    1. Structure is composed of RNA and proteins located in Rough ER and free floating
    2. Function is to synthesize polypeptides
    3. Prevelant in all cells
  2. Filaments
    1. Structure is long chains of proteins that make up hair, muscles
    2. Function is to bind cell aprts to give strength and rigidness
    3. Prevelant in skin and muscle cells.
  3. Microtubules
    1. Structure is long hollow tubules that make up cytoskeleton
    2. Function is aid various cell processes involving transport and movement
    3. Prevelant in flagella, mitotic spindles
  4. Cilia & Flagella
    1. Structure is made up of a microtubules
    2. Function is motility of cell or matter around the cell
    3. Prevelant in respiratory tract, fallopian tubes and sperm


Today we are going to look at some important cell parts that are not part of the endomembrane system,

these are the non-membranous organelles. Ribosomes, filaments, microtubules, cilia and flagella are all important cellular structures that are not comprised of membranes.

Beginning with ribosomes, these structures are made out of protein and RNA and are the actual location where proteins are synthesized. One way to remember this is to think about the first part of the word “rib” which is a source of protein.  This structure has 2 subunits that come together and allow for the meet up of two other types of RNA, mRNA the instructions for making the protein and tRNAs, which carry the correct amino acid for building the peptide chain of protein. 

Filaments are long chains of proteins made by cells for structure and function. Above you can see thin filaments called actin that combine with the thicker filament myosone that allows for a muscle cell to change its shape and contract. Filaments also build hair strands and thicken skin cells with keratin (in red).

Microtubules are also protein-based organelles that are long and tube shaped. Their design can aid in cells transporting materials including chromosomes during mitosis.

Cilia are fantastic organelles that aid in movement. above you can see how they line the respiratory tract. These structures keep lungs free from debris anr are known to become paralyzed and non-functional over time in smokers. Flagella are also organelles that aid in the motility of cells with their flag like motion, as seen by the sperm as it approaches an egg cell for fertilization. 

So in summary, non-membranous organelles are the ribosomes that make protein, filaments that provide structure to skin, muscle and hair, microtubules that allow for the transport of items in the cell, and cilia and flagella that promote motility on the outside of the cell. 

Thank you for joining us for this quick overview on the non-membranous organelles, now go be your best self today and happy nursing!