#endomembrane system

[darkblackmoons]

earlier today i was studying the endomembrane system as one does and came across a protein called Rab. Now my first thought was “wtf is regulus arcturus black doing there”

[kitteyrenlover]

positives in my life right now: im going to make dino nuggets

negatives in my life right now: i need to piss but 2 kittens are asleep on me so legally i cant move

verdict: i can neither get up to piss nor to preheat the oven. but also. kity

[cats-myelin]

<The endomembrane system>

There is a crossover bio and psychiatry joke to be made here... Anyway, dissociative disorders and phenomena of the mind aside, let's dive into the physical world with the endomembrane system: a continuum starting at the outer nuclear enveloppe that includes the endoplasmic reticulum (both rough and smooth), the Golgi apparatus and the vesicles and lysosomes it produces.

Each member of this membrane system has one or more function:

The Rough endoplasmic reticulum is responsible for most of the cell's protein synthesis.

The Smooth endoplasmic reticuluum is responsible for lipid synthesis and has detoxification functions (which it shares with peroxisomes.)

Vesicles are involved in transportation of material, exchanges throughout the cell and into the extracellular matrix.

Lysosomes are specific types of vesicles, nearly a hundredth the size of the cell, in charge of breaking down cell parts, old organelles or endocyted material like bacteria... They 'digest' the excess, unwanted material.

[dolivia]

All About Endomembrane System: Components & Functions

Explore the intricacies of the endomembrane system function and get insight into its essential elements and operations. Learn more about the roles that these structures play in cellular functions.

[billyojai]

Being No One: Consciousness, The Phenomenal Self, and the First-Person Perspective

Being No One: Consciousness, The Phenomenal Self, and the First-Person Perspective

From Being No One: Consciousness, The Phenomenal Self, and the First-Person Perspective by Thomas Metzinger, director of the theoretical philosophy group at the Johannes Gutenberg University of Mainz.

Astronauts in space frequently get the following problem: they cannot feel where up and down is in their body anymore. It’s like a radical version of motion sickness…Every astronaut knows how to…

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[sciencesoup]

Endosymbiotic Theory

The simple question of the origins of the mitochondria and chloroplast takes us all the way back to the origins of complex organisms.

Unlike the other organelles, which originated inside the plasma membrane, the mitochondria and chloroplast were once primitive but independent prokaryotic cells, most likely a type of bacteria. The endosymbiotic theory proposes that ancient prokaryotes engulfed each other around 1.5 billion years ago. Although this would usually result in the unfortunate engulfed cell becoming a meal for the host cell, for some reason, sometimes the digestion failed. Eventually, the swallowed cells were allowed to just hang out there, because the host cells realised they were beneficial.

To understand why, we have to understand how organisms are classified based on their metabolism. There are two main types: autotrophs, which make their own food, and heterotrophs, which rely on energy made by other organisms. Within each category are phototrophs, which derive their energy from light, and chemotrophs, which derive their energy from chemical compounds. This table makes it pretty clear:

(Image Credit: Pearson Education)

Mitochondria are aerobic heterotrophs, meaning they create energy using oxygen, and chloroplasts are photoautotrophs, meaning they produce energy from light. When the mitochondria was stuck in the host cell’s cytoplasm, surrounded by other bits of half digested food, they had plenty of fuel to take in for themselves and convert it into cellular energy. Soon they must have been so bursting with energy that some leaked out, allowing the host cell to use it for their own cellular activities.

Having an houseguest that churns out energy would have been a huge advantage for the host cell, since it wouldn’t have to go to the effort of making its own. The mitochondria basically acted like an installed battery, and in return, it was given protection by the host cell. Something very similar would have happened with chloroplasts, though chloroplasts would have created energy from light rather than half-digested molecules. As the host and guest cell benefit from each other, the partnership is called a symbiotic relationship.

But eventually, the two came to depend on one another—the host cell stopped producing much energy by itself, and the guest cell stropped producing genes for protection. The relationship became more and more dependent, until the mitochondria and the chloroplast simply become part of the eukaryotic cell.

There’s significant evidence supporting this theory. Firstly, the mitochondria and chloroplast each have two membranes, one enclosing the other, as if they had one originally and then were given another when the host cell engulfed them.

(Image source)

Both also have their own DNA, which is circular in nature like prokaryotic DNA instead of the linear DNA of eukaryotes. They use it to produce proteins and enzymes. They also divide by binary fission (splitting one parent cell into two identical daughter cells) just like bacteria, and they don’t use vesicles to send or receive substances from other organelles.

It’s like the Endomembrane system is a bunch of kids who have grown up together, while the mitochondria and chloroplast are those weirdos who have just moved into the neighbourhood and like, absorb sunlight and radiate energy and all kinds of X-men-esque junk.

Further resources: Animation or read about Lynn Margulis, who first proposed Endosymbiosis

[affinitree-blog-blog]

reading for biology class and just want to send a shout out to the endomembrane system for being such an inspiration.  

that shit synthesizes, transports, exports, metabolizes, and detoxifies poisons. 

~*~!!dOn'T eVr LeT sUm1 TeLL u UR *2* sMaLL!!~*~

[survivingbio]

Inside the Cell

Cells are mainly composed of two main groups:

Prokaryote: no membrane-bound organelles, no nucleus

Eukaryote: many membrane-bound organelles, nucleus, mitochondria (and/or chloroplasts) produce ATP, rough ER has ribosomes on it for protein synthesis and processing, smooth ER is for lipid synthesis and processing

Endomembrayne system: transports materials (such as proteins) to specific zip code through nuclear pores

Cytoskeleton: held together by actin, intermediate filaments, and microtubules which all help to maintain the shape of the cell and monitor movement