Autophagy

00:00 So, one next big step and you may not have heard about this either.

00:05 This has been in the last decade or so that we've increasingly appreciate there's another pathway for degrading big stuff.

00:11 This is called autophagy. Autophagy means eating one's self.

00:16 This is how cells can maintain viability when they don't have a lot of nutrition.

00:21 They may actually atrophy.

00:23 They may suck up various organelles and just get smaller and smaller and smaller.

00:28 They're still alive but they've only been able to live because they're degrading self, so, autophagy.

00:34 It's also an important pathway for getting rid of big organelles.

00:38 So, previously, we were talking about degrading proteins, degrading phospholipids or gangliosides.

00:45 Now, we're gonna degrade a mitochondria. Think about it.

00:48 How does a mitochondria get degraded? It's a big thing.

00:51 Well, we do it through something called autophagy.

00:54 So, what we have is some sort of recognition that an organelle or big cluster of proteins, something big is senescent.

01:05 It needs to be degraded because of the normal turnover process and we wrap some bits of the rough endoplasmic reticulum around it to form a vesicle which is called the autophagosome, so, self-eating particle.

01:18 And in their various organelles and proteins and part of the cytosol.

01:21 We then will fuse that with lysosomes.

01:25 So, this is a way that we can break down really big stuff within the cell and when we get that fusion, the lysosomal hydrolases will get in there and break down that senescent mitochondria, that senescent ribosome or that senescent peroxisome, whatever is in there.

01:44 And then, we break down and release the kind of elemental components, the amino acids and the lipids and stuff and we get to recycle them.

01:51 Perfect, so, normal process, we use it for normal turnover big things, also really important, if we get starved. If there's no nutrition and the cell has to exist, it uses autophagy to survive.