Question

Could someone explain what a thymine dimer is?

Answer 1

Are you referring to the abnormally bonded adjacent thymine bases in DNA?.

Answer 2

Yes, if that is what is being referred to in this article:
http://www.scientificamerican.com/article/how-does-ultraviolet-ligh/

Answer 3

Yeah it's the same thing. Think of a contusion or a wound. Basically, while the cellular process tries to heal the wound if there is an error that occurs in that process it creates an infection or on a DNA bases, a mutation.

Answer 4

The mutations can stop cell replication and the cell can lose viability or cell division may stop while the cell repairs the damage and it will begin again once the damage is corrected.

Answer 5

So in DNA like above, what happens?
The UV light does something to it and then the DNA has to fix itself and that takes time?

Answer 6

Basically, but within that time frame an error can occur in the process creating a that mutation. Effects vary from bacteriocidal effect to bacteriostatic effect

Answer 7

I don't know what those effect terms mean... So what exactly does the UV do to the thymine? Bend it?

Answer 8

This isn't an area of expertise but i imagine if you have a DNA Sequence of ATTCGCG and the complimentary is TAAGCGC and the sequence produces a lesion. the Original repairs and mutates into something as ACGCGCG. Or something along the lines of what Somy posted.

Answer 9

So the UV destroys the bond between the T and the A and then when the DNA fixes the damage, there may be a mistake?

Answer 10

Not really.

Answer 11

??? :/

Answer 12

Well, something along those lines i would imagine?

Answer 13

Is this a good description?
https://www.youtube.com/watch?v=ozmz7ztj_8A

Answer 14

Imagine in a sequence
you have 2 thymines in a row
when UV radiation is directed to it, it causes the thymines to covalently bind to each other, which means that the will not be able to connect to their complementary base on the other strand and thereby form a bulging in the sequence

Answer 15

So would that affect the amino acid if they are on a different codon?

Answer 16

OHHHHHH!! It makes sense!! The UV causes a bulge and then the enzymes that work in transcription don't know what to do so there is no protein production?

Answer 17

Polymerases cant continue replicate that region so they have to correct it first

Answer 18

yep
not until it is fixed
neither replication nor transcription can happen in such a state

Answer 19

Thank you guys so much!
So, I know this is sort of a different question, but how does this relate to skin cancer? Is the division of cells now unregulated by the unproduced proteins.

Answer 20

Nope. Dont mix two issues

Answer 21

Skin cancer is not a small topic, and there are different types of skin cancer.

Answer 22

UV light does play role
For example in melanoma
Have you learnt the histology of skin?

Answer 23

Cell types present in each layer that is

Answer 24

that video is good.

Answer 25

No, but I have heard of malignant melanomas that can sometimes be cancerous.
What you said made a lot of sense going along with the video. :)

Answer 26

That is true. Malignant melanoma is the top killer among all skin cancer types

Answer 27

If you want direct correlation between Thymine dimer type of mutation and a disease, you can read about Xeroderma Pigmentosum, it can potential cause skin cancer.

Answer 28

In that disease, thymine dimer mutation cannot be fixed as in a normal individual

Answer 29

Did i answer all of your questions?

Answer 30

Interesting. Yes! I'm in debt by you @Somy Many thanks. I'm sorry I didn't respond, I was taking notes! :)

Answer 31

Its okay, no problem :) Its good to see people actually wanting to learn :D

Answer 32

@rarecigs did i answer your question too? if not id want you to expand it

Answer 33

A thymine dimer is formed when UV hits of the electrons of \(\pi\) bond of the ring in thymine ring.

When two thymine groups are adjacent to each other, and UV light excites one of the \(\pi\) electrons, these can attack the other thymine molecule, fusing the rings together - forming a "dimer". "di" meaning 2