USMLE STEP 1: BIOCHEMISTRY ~ DNA REPLICATION (KEEP TELLING THAT STORY) 

Hi Dr. Neil. What’s the best way to reach you and send questions?

Umer... PERFECT TIMING.

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Merocode, Thank you for taking time to comment. I'm glad the videos have been helpful.

Sounds like plan... it just may take a while... plus, I think PATHOMA has the market on that one...

Sadaf, You are most welcome.

Paloma, Glad it was helpful... I need to keep expanding it... I just got side tracked.

Shiv, Glad it was helpful. Keep studying HARD!!

Appreciate the comment Youmna.

This should be the last time (hopefully).

PERFECT!!

Glad it was helpful.

Thank you Mirley.

hardly, but thank you.

Xaaboo, Hope it is helpful. Keep studying hard.

@@RandyNeilMD I’m KBMS student, final year of my specialty to become a nephrologist, but I’m also studying USMLE meanwhile, your videos are utmost resource I’m using ! Thanks always sir, really appreciate your efforts making all those videos for free…

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You are most welcome. Glad it was helpful.

Glad it was helpful... Look forward to the day.

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Perfect.

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Thank you M

Not a problem... :))

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Living the dream...

DNA polymerase 3 replicates the leading strand and lagging strand from 5' to 3' then proof reads to make sure that there is no wrong bases inserted via exonuclease activity in the opposite direction 3' to 5'. DNA polymerase 1 replicates the lagging strand in just the areas were occupied by the RNA primer so in order to do that it needs to have the same functions of DNA polymerase 3 plus the ability to excise the RNA primer By exonuclease in the direction of 3' to 5'. I like to think about it DNA polymerase 1 cuts RNA primer nucleotide from 3' end( this is the function of 5' to 3 exonuclease) and replace it by adding nucleotide to the 5 end of the previous fragment and so on till done from replacing the entire piece of RNA then it can do the proof reading from 3' to 5' to make sure that every thing is good ( that part is similar to DNA polymerase 3)

@@tarekhanna2647 so polymerase 1 can work in both directions. 3 only in 5 to 3 prime?

@@HassanPoyo DNA Polymerase 1 building DNA in 5'to 3' which is the usual direction and exonuclease activity from 3' to 5' like DNA polymerase 3 plus exonuclease from 5' to 3' to be able to remove the RNA prime

@@tarekhanna2647 so both polymerase 1 and 3 can work in 5 to 3 and 3 to 5 direction?

@@HassanPoyo 😂😂😂😂 DNA polymerase 3 and DNA polymerase 1 build DNA from 5' to 3' and proof read read via exonuclease from 3' to 5'. ONLY DNA polymerase 1 has also 5' to 3' exonuclease activity to enable him to remove the RNA primer pieces. try to read my initial comment now and see if it makes sense. Sorry if I confused you more.

It's has to be in 5 --> 3 prime direction

@@RandyNeilMD yes but why cant they be continous.

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