3' and 5'????

I don't understand what this 3' and 5' is about. I know they go on the end of the strand of DNA but I'm completely lost with what they mean/do.

I tried googling but didn't understand the results.

Can anyone explain in VERY simple English please?

They don't really do anything

They are basically just the ends of the strand like you said.

In DNA replication (where more DNA is made) a primer (short sequence of dna) is attached onto the 3' end.

I can't see you needing to know anymore? I am a scotiish student btw so maybe we learn it differently and need to know different things?

Ok.....so at the end of the strand do they go across the connectors or just on one side? Like are they there on the ends of unraveling DNA? And why 3 and 5? It sounds to me like they just picked those numbers out of thin air.

I'm a first year student in the US.

I don't understand what this 3' and 5' is about. I know they go on the end of the strand of DNA but I'm completely lost with what they mean/do.

I tried googling but didn't understand the results.

Can anyone explain in VERY simple English please?

When I was studying AS biology, this video helped me understood the 3' and 5' ends of DNA.
[video="youtube;L156Sbjs7zU"]https://www.youtube.com/watch?v=L156Sbjs7zU[/video]

That was a really helpful video. I see why it's 3 and 5 now.

Thank you!