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  • So say you have a clone or a secret identical twin because you know that a twin or clone is a genetically identical

  • person to you, which is crazy!

  • But it's true. Anyway,

  • So you have this clone or twin or what have you, and your parents decide?

  • that it's too much trouble to keep both of you

  • And so they give your clone to a kind of sketchy traveling circus. Now

  • I know your parents probably wouldn't actually do this, but just roll with me for a minute.

  • So for the purposes of this example let's just say that you grew up living a normal suburban

  • American life while your clone grew up with less stability and less access to nutritious food and less education.

  • But more exercise and more access to sword

  • swallowers and bearded ladies. And let's say you guys are 50 years old, whatever, you get together and have some lunch.

  • So you sit in there across the table from your clone.

  • What do you think you see? Well for starters,

  • Clone probably has a tattoo on its face.

  • And if Clone had stayed in the circus Clone probably, you know, professionally rides a unicycle

  • over a tightrope, so Clone is probably in pretty good shape. But then again Clone

  • probably smoked cigarettes and

  • probably was malnourished as a child so might be slightly shorter than you. By the same token, let's say that you've been eating sonic tater

  • tots five days a week since

  • 1992 so you're looking a little bit tubby. Plus, you spent the last 20 years at a really stressful job that puts you at risk

  • for all kinds of weird health complications. So at 50, you and Clone would probably look pretty different from one another.

  • But it turns out you don't just look different. You actually have become

  • different. Now, if some scientists looked at your genetic code

  • they would say that your DNA was still exactly the same as that other person. That is to say, if your

  • Genome is a paragraph all of the letters would be in the exact same [word]

  • But on another level there would be a huge difference and if we extend this metaphor

  • We can say that the letters are in the same order

  • But the spaces in the punctuation are all in different places of course completely

  • Potentially changing the message of that paragraph the study of this genetic punctuation that I'm talking about is called epigenetics which literally means

  • Above genetics the epigenome doesn't change your DNA

  • But it decides how much or whether some genes are expressed in different cells in your body?

  • Epigenetics looks at what happens to your genes over the course of your life and whether those

  • changes could be passed down to your children or even your grandchildren

  • So here's the way epigenetics works you have billions of cells in your body and they each contain

  • Your dna the same exact blueprint of your genetic code

  • But just because they have the DNA it doesn't mean that they know what to do with it

  • They need outside instruction from these little carbon and hydrogen

  • Compounds called Methyl groups the way these Methyl groups control the genome is by binding [to] a gene and saying do not

  • Express this Gene the Methyl groups bind

  • Differently to your genome and a skin cell versus say a tongue cell or an eyeball cell and that is one of the ways that

  • A cell knows that hey, I'm the skin cell or hey. I'm an eyeball cell hey

  • I'm a muscle Cell. In addition to Methyl groups epigenetics is also controlled by

  • Histones which are proteins that are basically the spools that DNA winds itself around histones can change how tightly or loosely?

  • The DNA is wound around them if they're more loosely wound the genes can express more and if they're more tightly round than they express

  • Less so whereas the Methyl groups are more like a switch the histones are more like a knob

  • Every cell and your body has a distinct methylation and histone pattern and that is what gives

  • Every cell its marching orders think of your genome the DNA is the actual hardware of the computer

  • While the

  • epigenome is more like the software which tells the hardware what to do the genome is what's going to be doing all the work but

  • the epigenome is going to be telling it what to do so the hardware of your DNA is going to be the same throughout your

  • Entire life, but these epigenetic tags do change throughout your life

  • And they decide what genes get expressed or not. Now epigenetic information in a cell?

  • Isn't permanent it can change throughout your life, and it can be hereditary

  • And it can change over time especially when your body is going

  • Through a lot of changes like say during puberty a bunch of Methyl groups kick in they're like okay

  • So you guys over here? You're gonna have [to] start growing hair, and you guys over here

  • I really need you [guys] to get behind giving this guy's some really horrible

  • Acne or like when you get pregnant which hopefully I won't but when you do your epigenome has to be like [alright] guys

  • [everything's] about to get a whole lot bigger in here

  • And we're gonna have to pass something the size of like a miriam Webster's dictionary through that little pipe over there

  • So let's get this thing done, but it's not just these dramatic times when the epigenome is changing

  • It changes suddenly throughout our entire lives

  • [and] it changes based on a lot of environmental factors like what we do what we eat

  • What we smoke and how stressed out?

  • We are in a daily basis scientists have found that things like a bad diet can actually lead to Methyl groups

  • Binding to the wrong place and making mistakes and with those bad instructions cells become

  • Abnormal and become a disease and then basically all hell breaks loose

  • And you get cancer or something epigenetics is a very young science though. We've known about the epigenome since the 1970s

  • It's only in the last 20 [years] that we've even known what

  • Effect these epigenetic tags are having on our DNA and even after they got all that

  • business straight

  • Scientists still thought that all of our epigenetic tags were stripped off of our genome before they were passed on to our children

  • So if you started smoking 10 packs a day when you were 10 years old that would certainly be a horrible health decision for you

  • But you wouldn't necessarily be harming your unborn children in any measurable way however the thinking on [that] is changing pretty rapidly

  • because it's true that a [lot] even most of the

  • Epigenetic information from a parent is stripped off of the embryos genome in the first few days and fresh ones are created

  • Specifically for this new person however some [of] these tags get stuck on the genome and are passed down from generation to generation

  • [and] it just so happens that the more they study this the more it looks like bad

  • Epigenetic information is being passed from generation to generation

  • [and] this is a whole new way to think about how we pass information between generations your grandmother was making dietary decisions

  • that affect you today as we experience all these new strange epidemics diabetes autoimmune

  • disorders cancers that weren't appearing in Previous generations

  • It's starting to look like these may be caused by epigenetic information passed down from our parents

  • I know it's such an unbelievable Buzzkill

  • there is no point in our lives when we can do anything without guilt anymore [the] discovery that the

  • environmental Factors the parent experiences can be passed down from generation to generation was sparked in the

  • 1980s and this happen when some scientists were looking at the birth and death records of some people who lived in [nineteenth-century]

  • Sweden as is a weird place to find a genetic revolution, but there it is wasn't just any place in Sweden

  • It was in Norrbotten. Which is the Northernmost County in Sweden

  • Which is literally in the arctic circle and despite the fact that [norrbotten] was literally the worst place

  • you could possibly choose to live in sweet there were some people living there in the

  • 1800s and they were completely cut off from the rest of the world let me clarify these people were

  • Isolated like if they didn't have a good crop year people died no, it wasn't ideal

  • But you know they didn't ask me my opinion

  • So I'm not giving it

  • So anyway these people subsisted entirely on what they grew when the animals that they raised and like I said

  • Sometimes they starved but sometimes they had huge bountiful years of plenty and what happened people totally went ape crackers

  • I mean of course they did because they were so freakin hungry

  • and then all of a [sudden] there was all this damn food everywhere anyway there was a public health specialist who was looking at the

  • effects of the people who grew up in the really bad

  • Starving periods of time versus the people who grew [up] in the eat all you can at the smorgasbord

  • Years you might already be guessing what they found out people [who] went from relatively slim pickins to feed your face until you have to

  • Barf and then do it all over again in a single season those people got an average of six years sooner than [they're] starved out

  • Counterparts, and you know it sucks, so do their kids instead of their kids kids who epigenetics

  • So of course now we all know and we're all going to stop doing unhealthy things

  • starting today

  • Unless the damage is already done the damage is

  • almost certainly already done, but hey

  • epigenetics brings good tidings along with bad ones

  • for instance

  • We now know that certain types of cancer are caused by misplaced epigenetic tags and scientists are now developing drugs that can

  • Silence the bad genes that were supposed to be turned off in the first place

  • additionally until recently we thought

  • That genes were the end all and be all of who you got to be they were your blueprint and you couldn't escape them this

  • Outlook is [not] just kind of depressing and also alludes to a yucky sort of social prejudice because when you look at Data without considering

  • Social and epigenetic factors it might look like people with less money are less intelligent

  • So just like 15 years ago there were scientists saying things in public mind you like some people just have good genes for

  • Intelligence and it just so happens that the poor people don't all it's so sad too bad poor people

  • But you have bad genes [well] turns out that that is not even a little bit true

  • Not only are there a huge variety of social factors that affect

  • How well people do on intelligence tests that a genetic trait is also, not just a product of genes

  • it's also a product of environment any one person's genome was determined by any number of

  • Is made by any number of their ancestors and right now you are making decisions that are going to affect [people] who are alive?

  • long after you were Dead

  • [no] pressure or anything and so I'm glad you've watched this because when you and your clone are in your 60s

  • And you sit down have lunch, and he brings his son and his son has a tattoo on his face

  • He did not inherit that from you. This is Hank Green from the Scishow. We hope you learned something.

So say you have a clone or a secret identical twin because you know that a twin or clone is a genetically identical

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エピジェネティクス (Epigenetics)

  • 44 4
    robert に公開 2021 年 01 月 14 日
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