Genetic Mutations Explained


I have great news. You don’t have to watch a movie to see a genetic
mutant. You’re surrounded by mutants. You probably are a mutant. But how do mutations work, and when can we
expect to see your genetic superpowers? Let’s find out. It takes a staggering amount of genetic information
to make you who you are. You have just over 3 billion DNA pairs in
your genome. If you were to print your genome in a set
of hardcover books, you know, for posterity. Great Uncle John’s big book of genes. That one set of books would be over five hundred
times as long as the Harry Potter series. And your normal body cells have twice that
amount of information, with two slightly different copies in each cell! So Great Uncle John’s big book of genes is
really, really big. Every time your cells divide, they split the
DNA in half and make a copy of the whole thing. How long do you think it takes to copy a thousand
Harry Potter series, letter for letter? [pause] It takes an hour. Let that sink in. One hour. Your cells are copying information faster
than a procrastinating student on the day their 20-page final essay is due. And they copy AMAZINGLY well. We are still figuring out the numbers, but
it’s something like 60 errors during this copying. And your cells have error-checking molecules
that come along afterwards and fix almost all of those errors. Okay, now let’s talk about those mutations. Most mutations are when one letter of the
genetic sequence is replaced with a different letter. Let’s use a sentence from Harry Potter to
see what that means. “Harry pulled off the Invisibility Cloak and
threw himself into an armchair in front of the fire.” -JK Rowling, Harry Potter and the Goblet of
Fire “Harry pulled off the Invisibility Cloak and
threu himself into an armchair in front of the fire.” This is a nonsense mutation where a letter
is turned into a STOP. “Harry pulled off the Invisibility Cloak an.” Some mutations, though, change the meaning
of a gene. “Harry pulled off the Invisibility Clock and
threw himself into an armchair in front of the fire.” That sentence doesn’t mean the same thing
it used to. What is an invisibility clock? It’s something new! Then there are the really bad mutations. This is a deletion mutation where we lose
most of the paragraph. “Harry pulled off the Invisibility Clowas
sitting in the fire.” And frameshift mutations happen because DNA
doesn’t have spaces or punctuation to differentiate between words, so a shift in letters can
shift the whole rest of the sequence. “Harry pulle dof fth eInvisibilit yCloa kan
dthre whimsel fint oa narmchai ri nfron to fth efire.” I would like to take a moment now and be amazed
at how anything can be alive. Thank you. What causes mutations? Like we said, there are sometimes errors in
copying DNA. There is also a thing called recombination,
where DNA in one group gets mixed up with DNA from another group. That can lead to extra copies of genes, or
deleting genes. Some chemicals damage DNA in different ways. And radiation is varying degrees of bad depending
on its strength. UV light from the sun can bump DNA apart,
which rarely causes mutations. Gamma rays have way more energy and can cause
double-strand DNA breaks, which are much more likely to result in mutations and also death. If we live in a world with mutation-causing
chemicals and solar radiation, how can anything live? We have enzymes that repair DNA and correct
errors. And oddly enough, almost all mutations have
no effect at all. Nothing good, nothing bad, just invisibly
present. Most of the remaining mutations are bad, leading
to impaired or dead cells. Or in the worst case, to diseases like cancer. But every now and then, a chance within a
chance, something good happens. A baby is born with slightly higher resistance
to malaria, or the ability to eat milk into adulthood, that gives them a slightly better
chance of survival. These genes tend to spread through the population. And as they spread, they combine with other
useful genes. These superpowers accumulate over generations. And the result is the 6 billion bits of gene
data that turned into you. How super is that? Thanks for taking the time to learn about
your mutant powers. I hope you use them responsibly. If you would like to know more about the amazing
properties of Life, you can watch one of these videos, and you can subscribe to know when
a new combination of information pops up. Thanks for stopping by this week to learn
what makes Life awesome!

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