Free Radicals Effect on Cellular Activities

00:00 Right now, let's just look at an example of what happens in terms of protein synthesis, they kind of give this some reality.

00:06 So here we have a bit of a membrane.

00:09 This would be rough endoplasmic reticulum.

00:11 And on the surface of the rough endoplasmic reticulum is ribosome it's translating its protein through into the middle of the looming of the rough ER.

00:20 Life is good, except now we have ingested or inhaled or done something where we've gotten a fair little high dose of carbon tetrachloride.

00:32 This is a compound used in dry cleaning fluid, fairly common, and we metabolize it in enzymes that live in the endoplasmic reticulum.

00:43 In particular the cytochrome p-450 system, which is not a detoxifying system.

00:49 It is a solubilization system.

00:52 It's taking something that's lipid soluble and converting it to something that is more water soluble, so it could be excreted.

00:59 Cytochrome p-450, in that same endoplasmic reticulum, takes our carbon tetrachloride and converts it to carbon trichloride with a free radical.

01:10 Oops, now we have a free radical in the middle of a whole bunch of lipid.

01:15 What's gonna happen? It can be predicted.

01:18 We're going to start in an autocatalytic way, breaking down that entire membrane, and we're getting more and more and more free radicals as because it's autocatalytic.

01:27 As we now break down the rest of lipid, and the lipid is falling apart.

01:33 Our membrane is dissolving, it's become a detergent.

01:36 When that happens, our ribosome goes away.

01:39 It can't bind anymore, so we're protein synthesis goes to zero.

01:43 Not so good.

01:46 Fortunately, we do know that we're going to encounter things like this, so we have ways to sup up, to scavenge free radicals.

01:54 And vitamin E is one of those, it lives in membranes in various places, including the endoplasmic reticulum.

02:00 And it can be a free radical scavenger, so it is a way to potentially stop this.

02:05 There are limits, you only have a certain amount of vitamin E in your tissues, so you cannot make infinite amounts of free radicals and expect to get away with it.

02:13 But it is a mechanism by which we protect ourselves.

02:17 And now there's some other mechanisms by which we protect ourselves from free radicals.

02:23 So here's the effect on cellular activities and death.

02:27 If we look at our normal rough endoplasmic reticulum, and our normal mitochondria, they have a certain structure and architecture, and they look fine.

02:36 If we now hit them with a free radical, in this case, carbon tetrachloride.

02:41 The ribosomes have left rough ER and our mitochondria are swollen.

02:45 So we're not making protein and we're not making ATP.

02:49 When that happens, we will get cell death.

02:51 So this is on the right hand side is a liver.

02:54 In an experimental animal that's been exposed to carbon tetrachloride, and we're getting these areas of necrosis.

03:01 Cell death, cellular homicide and those are pointed to with the arrows.