What happens when your DNA is damaged? – Monica Menesini
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What happens when your DNA is damaged? – Monica Menesini


The DNA in just one of your cells gets damaged tens of thousands
of times per day. Multiply that by your body’s
hundred trillion or so cells, and you’ve got a quintillion
DNA errors everyday. And because DNA provides the blueprint for the proteins
your cells need to function, damage causes serious problems,
such as cancer. The errors come in different forms. Sometimes nucleotides,
DNA’s building blocks, get damaged, other times nucleotides
get matched up incorrectly, causing mutations, and nicks in one or both strands
can interfere with DNA replication, or even cause sections
of DNA to get mixed up. Fortunately, your cells have ways
of fixing most of these problems most of the time. These repair pathways
all rely on specialized enzymes. Different ones respond
to different types of damage. One common error is base mismatches. Each nucleotide contains a base, and during DNA replication, the enzyme DNA polymerase
is supposed to bring in the right partner to pair with every base
on each template strand. Adenine with thymine,
and guanine with cytosine. But about once every
hundred thousand additions, it makes a mistake. The enzyme catches
most of these right away, and cuts off a few nucleotides
and replaces them with the correct ones. And just in case it missed a few, a second set of proteins
comes behind it to check. If they find a mismatch, they cut out the incorrect nucleotide
and replace it. This is called mismatch repair. Together, these two systems reduce
the number of base mismatch errors to about one in one billion. But DNA can get damaged
after replication, too. Lots of different molecules
can cause chemical changes to nucleotides. Some of these come
from environmental exposure, like certain compounds in tobacco smoke. But others are molecules that are found
in cells naturally, like hydrogen peroxide. Certain chemical changes are so common that they have specific enzymes assigned
to reverse the damage. But the cell also has more general
repair pathways. If just one base is damaged, it can usually be fixed by a process
called base excision repair. One enzyme snips out the damaged base, and other enzymes come in to trim around
the site and replace the nucleotides. UV light can cause damage
that’s a little harder to fix. Sometimes, it causes two adjacent
nucleotides to stick together, distorting the DNA’s double helix shape. Damage like this requires
a more complex process called nucleotide excision repair. A team of proteins removes a long strand
of 24 or so nucleotides, and replaces them with fresh ones. Very high frequency radiation,
like gamma rays and x-rays, cause a different kind of damage. They can actually sever one
or both strands of the DNA backbone. Double strand breaks
are the most dangerous. Even one can cause cell death. The two most common pathways
for repairing double strand breaks are called homologous recombination
and non-homologous end joining. Homologous recombination uses an undamaged
section of similar DNA as a template. Enzymes interlace the damaged
and undamgaed strands, get them to exchange sequences
of nucleotides, and finally fill in the missing gaps to end up with two complete
double-stranded segments. Non-homologous end joining,
on the other hand, doesn’t rely on a template. Instead, a series of proteins
trims off a few nucleotides and then fuses the broken ends
back together. This process isn’t as accurate. It can cause genes to get mixed up,
or moved around. But it’s useful when
sister DNA isn’t available. Of course, changes to DNA
aren’t always bad. Beneficial mutations
can allow a species to evolve. But most of the time,
we want DNA to stay the same. Defects in DNA repair are associated
with premature aging and many kinds of cancer. So if you’re looking for
a fountain of youth, it’s already operating in your cells, billions and billions of times a day.

100 thoughts on “What happens when your DNA is damaged? – Monica Menesini

  1. Microbiology and Cell Science student, here! This video is an absolutely AWESOME introduction for anyone curious about DNA repair pathways used in human bodies and in microbes! I hope this inspires young students to become future molecular geneticists. Thank you for this video!!

  2. And we are supposed to believe that someting as random as the big bang created these perfect beings?… it really must be hard not to believe in God

  3. Amazing how our body works. It's just a shame that people though they were accidentally made. Like an incredible structure but nobody intelligently engineered it. Like a skyscraper but the wind designed it accidentally lol. It's just a shame that they don't acknowledge a Greater being who engineered all of these wonders. More intelligent than the most intelligent person on earth.

  4. i find it fascinating how our bodies are doing everything to keep us alive and yet some people decide to harm themselves and put toxins inside their bodies 🙁

  5. And who programmed our DNA? The Lord Jesus Christ did!
    John 1:1-3
    (1)  In the beginning was the Word, and the Word was with God, and the Word was God.
    (2)  The same was in the beginning with God.
    (3)  All things were made by him; and without him was not any thing made that was made.

  6. Is there a parity bit or error correction code or hashing signature or something else to detect & repair the error?
    How they know something changed? By comparing the healthy one? How they know which one is healthy and other damaged?

  7. I love Ted ed animations…! If u want to fall in love with your own body… Don't see a mirror or read self-love quotes… Just watch one of these videos and imagine such cute workers working inside you to make you look the way u are… Ha ha ha…😂😄🤗💕

  8. SUM:
    Specialized enzymes: different types respond different type of damage.
    Common error BASE MISMATCHES : when nitrogeous base mismatches enzyme changes it if it nor realize second sets of proteins make it correct
    CHEMICAL CHANGES TO nucleotides: usually they have certain enzyme to repair
    if ONE BASE DAMAGED it can be repair process called BASE EXCISION REPAIR( replacing nucleotides)
    UV light damage is harder to fix : NUCLEOTIDE EXCISION REPAIR team of oroteins removes long strand of nucleotides
    DOUBLE STRAND BREAKS MOST SEVERE: homologus recombination (use template) non-homologus (no template) fusion

  9. But of course it is ALL BY CHANCE. If I saw a factory that worked seamlessly like this I would certainly assume that it was all by chaotic chance and certainly not something that was thought up, DESIGNED and then consistently implemented.

    And yet, that is what many will say after watching this video of just one SMALL funtion that our bodies do! No design shown just changes from chance. I guess like how chance and necessity is causing our bodies to rid itself of Cancer.

    Forget if you believe that the cures for cancer are being withheld or not, regardless, based on the premise of Evolution caused by the onset of negative environmental challenges, our bodies should be creating immunities.

    Oh that's right for the body to do that it takes Millions of millions of years something we would never see. But lets ignore that within years certain bacterium or deceases find ways to go around drugs or procedures that only stop them for a little while. But hey, its all by chance.

    I just can't wait for our bodies to adjust to pollution and global warming cause what the heck, we evolved through more serious catastrophes.

  10. I just realised that my body is smarter than me. I don't even know what these are, yet my body knows chemistry better than me.

  11. 3:17
    Proteins:X2 BREAK IN THE DNA
    PROTEINS2: RUN ALL FOR YOUR LIFE
    PROTEINS3:AHHHH WE ARE NOW OUTSIDE OF REPAIR CENTER BUT WHAT THE FU…….

  12. My DNAs know what they doing with their lives but I don't, and here I am watching a video about them. My DNAs must be disappointed with me.

  13. How is any of this possible unless there are pre-existing templates?
    Furthermore, does this not prove that our body parts are produced with pre-existing purposes and not just random accidents?

  14. This reminds me to take care of my body in all the ways I can, because it's doing so much for me. The least I can do is to love it and take care of it. 😊

  15. i love this video. I would like to show it to everybody. I would like to know who i can talk to in order to clear that i can show it to everybody without problem or violation of trademark etc. Any advice? Who can i contact? Sincerely , Leon R. Katz

  16. You can thank Evelyn Wilkins of Rutgers University who discovered this process. Where's her Nobel Prize in Physiology/Medicine? She deserves it 10 x over!!!!

  17. Such an incredibly complex and intricate repair system. I really can't picture such efficiency and specificity coming to being on accident. How could a system like this evolve out of nothing? I truly believe there is intelligent design.

  18. wow i can just amigine some protins screaming DNA DAMAGE! and the others like yea calm down itl be damaged again HEY CAN YOU COME FIX THIS PROBLEM IN THE DNA! lol

  19. I noticed that the DNA strand's sides are both running 5' to 3'. For the illustration to be more accurate, one side should run 5' to 3' and the other side 3' to 5'. This is a fairly old video, not sure if anyone updates…but thought it was worth mentioning. Other than that, great job!

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