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05.04 Membranous Organelles

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Overview

  1. Membranous Organelles-Organelles surrounded by a phospholipid bilayer found only in eukaryotic cells
  1. Rough ER
    1. Structure is a membranous extension from the nucleus that is studded with ribosomes
    2. A function is to produce proteins that are shipped outside of the cell
    3. Prevalent in muscle cells.
  2. Smooth ER
    1. Structure is a membranous network of tubules called cisternae that extend from the nucleus.
    2. Functions is to modify a variety of proteins and lipids.
    3. Prevelant in muscle and gonad cells.
  3. Golgi Apparatus
    1. Structure is flattened membranous discs that extend from the smooth ER.
    2. Function is to package proteins into vesicles for shipment via exocytosis.
  4. Mitochondria
    1. Struture is a small double-membraned compartment. Internal membrane (cristae) is folded to increase surface area.
    2. Functions is to breakdown sugars to produce ATP (aka Cellular Respiration.
    3. Prevelant in liver and muscle cells.
  5. Lysosomes
    1. Structures are small membrane compartments filled with enzymes
    2. A function is to fuse with vesicles and other ingested materials to breakdown and recycle materials.
    3. Prevalent in white blood cells

Video Transcript

So today we are going to talk about the ever so cool organelles exclusive to eukaryotic cells!

So the organelles we are going to discuss today are much like the nucleus in that they are surrounded by membranes. These are the Endoplasmic reticulum (rough and smooth), the golgi complex, the mitochondria and lysosomes. (Match words to structures.)

The endoplasmic reticulum is often abbreviated as the ER, which is obviously not the ER you are probably more familiar with. The word reticulum means net and endoplasm refers to the plasma (or membrane) inside the cell. The ER, both smooth and rough are connected to one another. The rough ER actually extends from the nuclear membrane. So as the mRNA leaves the nuclear pores it arrives at a ribosome on the Rough ER and synthesizes a protein where it can be processed in the rough ER. The smooth ER (without ribosomes) might modify the protein further and add a lipid or process other lipids necessary for the cell. Which brings us to the next oganelle a protein might travel through the golgi.

So let’s talk a bit about the Golgi. Call it what you will…. golgi, golgi body, golgi complex, golgi apparatus, so many names but honestly it is all the same thing. Any protein destined to leave the cell or become embedded in the cell’s membrane will need to get properly packaged for such an excursion by passing through this multi- nicknamed organelle. The golgi is a flattened membranous organelle that encases proteins in a secretory vesicle in order for it to then fuse with the cell membrane and export for some purpose outside of the cell.

It has been a huge meme sensation to refer to this organelle as the powerhouse of the cell.  This means that this organelle is able to slowly release the stored energy in glucose and convert it into a more usable form of cellular energy known as ATP. This process known as cellular respiration splits glucose and in the presence of oxygen can make up to 38 ATP molecules needed to power cellular activity. Key structure for this process includes the folded inner membrane known as cristae and the space inside the cristae called the matrix. Fun fact: evolutionary biologists think this organelle used to be a single celled organism because it has its own DNA!!!

When you hear the word lysosomes I want you think of the product Lysol…. which is designed to disintegrate germs! Lysosomes disintegrate whatever they fuse with! This makes for great recycling of cellular debris! (Explain steps 1-4)

So in summary…membranous organelles are exclusive to eukaryotes

Important examples are the smooth and rough ER that modify proteins and lipids respectively

Golgi whatever…… lots of names but they all package proteins destined to go!

Mighty mitochondria that are all about making that ATP from sugar.

and Lysosomes that disinfect, I mean disintegrate that which needs to be recycled in the cell.

Thanks for getting insane with the membrane organelles today. Now go out and be your best self today and Happy Nursing!

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