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Transcription and mRNA processing | Biomolecules | MCAT | Khan Academy

3114 ratings | 588751 views
Introduction to transcription including the role of RNA polymerase, promoters, terminators, introns and exons. Watch the next lesson: https://www.khanacademy.org/test-prep/mcat/biomolecules/dna/v/speed-and-precision-of-dna-replication?utm_source=YT&utm_medium=Desc&utm_campaign=mcat Missed the previous lesson? https://www.khanacademy.org/test-prep/mcat/biomolecules/dna/v/leading-and-lagging-strands-in-dna-replication?utm_source=YT&utm_medium=Desc&utm_campaign=mcat MCAT on Khan Academy: Go ahead and practice some passage-based questions! About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content. For free. For everyone. Forever. #YouCanLearnAnything Subscribe to Khan Academy’s MCAT channel: https://www.youtube.com/channel/UCDkK5wqSuwDlJ3_nl3rgdiQ?sub_confirmation=1 Subscribe to Khan Academy: https://www.youtube.com/subscription_center?add_user=khanacademy
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Text Comments (119)
Shahzade Sheik-Yousouf (23 days ago)
The verb 'splice' means 'to join together'. Unfortunately it has been used in the wrong context here, you don't 'splice out' the introns but 'splice together' the exons.
Tyrannosaurus Rex (25 days ago)
Thanks buddy!
김소혜 (1 month ago)
I'm Korean university student. This explainment helps for Test. Thanks.
Famine (1 month ago)
Gona kill my bio final. Thanks for the videos bro they've helped me so much. Very confident I'm going to get the A I need in this course!
Hrydra (1 month ago)
Why does the protein coming out of the ribosome look like anal beads at the beginning?
Emily123yh (1 month ago)
Question about the 'unzipping' part of transcription: My biology teacher told me that DNA helicase does this, however my Chemistry teacher told me that RNA polymerase does this and helicase is only involved in replication. Who is correct? :'( they're both great teachers. EDIT: after a lot of googling it seems pretty much 50/50 to either helicase or polymerase - if anyone knows which one it actually is please let me know how you know lol and why lots of people are mistaken. Any info would be really appreciated!
Emma Roden (1 month ago)
I hope that helps!
Emma Roden (1 month ago)
Helicase unzips the DNA during DNA replication. Polymerase unzips the DNA during RNA transcription. They do the same job in different contexts.
Ashley Groth (1 month ago)
not enough detail... TFs, phosphorylation factors... please!
Ash Avecilla (1 month ago)
thank you, khan academy, once again for saving my biology grade
Mahmut Akkuzu (2 months ago)
thanks for the video. thanks khan - acedamy
Rosie Ray (2 months ago)
I thought in RNA it's A-U but you out T-A??
Chibi Monsta (2 months ago)
2 yrs later i watch this once again! :))
JB fctory (2 months ago)
How does it know what the introns are to splice out?
JB fctory (1 month ago)
+Anna Dash GU is also code for amino acid, so does that mean it signals for both actions?
Anna Dash (1 month ago)
It's a splice site 5' GU sequence and 3' AG sequence. Spliceosome recognizes it and cuts it out
Rakesh Bhaskar (3 months ago)
Thanks a lot that a amazing explain..
ahmed abdulrhman (3 months ago)
realllllllllllllllllllllllllllllllllllllllllly huge thanks, you are great and amazing teacher
CK EB (3 months ago)
You are the best teacher I have ever seen
Prauke Fetry (3 months ago)
I am in goddam awe every time!!!
Do It Yourself (3 months ago)
Reggie Watts or what oh myyssghofisdf
THE REAL (3 months ago)
high school level toooooo much details you did not talk about that will help MED students
So the brain is not the complex thing on Earth. The Cells are
Suleman Bhatti (4 months ago)
Why does DNA replicate before cell division??
Dhwani Sanghvi (3 months ago)
So that the new cell gets equal amount of information from parent cell
Ali Alsaeed (4 months ago)
Thanks.what is the primary,secondary,tertiary and quaternary structure of DNA??and how hydrogen bonds contributed in stability of DNA?l want answers please
This is amazing! I found it hard to understand in class because of how shallow it was, but with more details it makes perfect sense! Thanks a lot.
Ornella Fera (2 months ago)
jap totally agree! THIS is always the problem. just explain it with its details directly - then it is much easier to understand :)
DezyncFILMS (5 months ago)
i dont know why we cut out the introns just because we dont know what they do yet?? what if they did something really important and we have just been cutting them out all the time??
Todd Secor (6 months ago)
This person has helped me better understand chemistry, trigonometry, calculus, and now biology. He is truly amazing. He should be the dean of MIT.
xxXRuby RedXxx (6 months ago)
I wish I would have found this while I was in microbiology, You explained in ten minutes what I couldn't even get from tutoring.
notworthit (6 months ago)
It's time to stop - Ethan Klein H3 H3 Productions
‘Los P (2 months ago)
*- Filthy Frank
Sam Stokes (7 months ago)
Dude thank you!!!! Very helpful!
kyloXD (7 months ago)
Anyone else feel the passion in his voice when he talks about these said topics?
Silvan Aban (7 months ago)
Thank you for this. This was extremely helpful!
Colton B (9 months ago)
Can someone please explain to me how mRNA synthesis can begin on 3' end of antisense/template strand if all of the promoting sequences (CAT & TATA) are toward the 5' end of the molecule? Is RNA polymerase reading both strands of the DNA molecule and only transcribing from the template strand? thanks in advance!
ouji subete o (6 months ago)
Colton B polymerases only able to build 5'-3'. Transcription goes only 1 way becase of antiparallel law. Remember how much work must be done to rebuild second chain in DNA replication (Okazaki framents)? Also you can see he put operator on the left side, RNA polymerase doesn't care which chain is it, it only recognize the start (3' in this case). If it was upper chain polymerase would have to start at 5' and build 3'-5'.
Mansi Raja (9 months ago)
Givee meee your handwriting 😻😻😻 and you actually have the capability of pinnng whatever you teach into my head!!
md mahatab (9 months ago)
I love you SAL
Maya Papaya (9 months ago)
if anyone wanted to know: spliceosomes​ are what cut out sections from the RNA strand to remove the introns and leave the exons
Demetra Kaskiri (10 months ago)
thanks for helping on my Biology test!
Edgar G. Kozlova (10 months ago)
Introns are believed to be regulation regions for transcription and genome evolution. Calling them nonsense is something not done anymore. Many things in molecular biology change every 6 months.
Yashsvi Dixit (10 months ago)
one of the very few productive khan
Derek Jennings (11 months ago)
Great video - thank you. I liked the very clear explanation of Ribosomal RNA (that it doesn't need anything else to code, compared to the DNA where it needs Helicase, RNA Primers, Ligase, etc.) I also really enjoyed learning about the difference between the mRNA in prokaryotes vs. Eukaryotes. It's interesing that the Introns do not have a specific purpose, so the mRNA, is made up of what's left over after the splicing takes place (exons) of that "pre- mRNA". Again - I greatly enjoyed this video, thank you!
Sten Calcabar (11 months ago)
not in depth enough, even though content is good and nicely explained (well just saw that it is for highschool, so nvm, for that this should suffice) [in my opionen]
Gazza-usa (11 months ago)
This is absolutely fascinating. Thanks for the great videos.
Sophie Van der Meer (1 year ago)
This video is supposed to be for high school students and I'm a med student learning the exact same material 😂
Aladin Ben Terzi (2 months ago)
i'm in first year chemical engineering but why on earth are we studying these stuff x))
sagar Adhikary (2 months ago)
jesus im in high school not knowing what their talking about
cpard2d2 (3 months ago)
I´m in a masters program and we´re learning this too. We go a bit deeper with the promoter sequences, transcription factors and the different polymerases but overall, it´s the same XD.
Réka Szabó (5 months ago)
I'm a med student too and I wish that this would be enough for the molecular cellbiology exam but it's not even close :'( Great video btw
Muaaz Butt (8 months ago)
And i thought i was alone xD
Moustafa Zain (1 year ago)
that is amazing ty very much
Olaniyan Olabode (1 year ago)
So the bacterial mRNA has no 5' cap?
Imabeatyouman (1 year ago)
Do you ever just study cellular biology and think about how little we actually know about this shit... like when you said, "the RNA complex changes" to let go of the strand, i thought, wow... things don't just change but hes right cause that's what is taught because that's just how we perceive what is occurring under a microscope
Xcorpian Kings (1 year ago)
amyzing
Queen Seth (1 year ago)
So so frustrating!!!! Different people are telling me different things!!!! Is it helicase or rna polymerase that separates the dna strands?!?!?!?!?!?!??
ironkreator (10 months ago)
In reality, the RNA polymerase is a holoenzyme that is located in a large pre-initiation complex (made up of RNA polymerase and 6 transcription factors). DNA helicase activity is found in TF2H. For simplicity, it is easier to say that in DNA replication there are distinct enzymes, like DNA helicase and topoisomerase that cause positive supercoiling and relieve that supercoiling via the introduction of negative supercoils, respectively. In transcription, it's easier to conceptualize that the RNA polymerase does it all itself, when in reality its a concerted effort by a variety of TFs in that complex. For the MCAT, which is the context of this video, the preinitiation complex is far too in-depth; however, in an upper-division biochemistry class, this is how it will be taught. Another example of this is the TATA binding protein included in the pre-initiation complex which positions RNA poly II on the DNA template strand which is also left out of this video. https://en.wikipedia.org/wiki/Transcription_preinitiation_complex Hope this helps.
Anisa Aprilia Adha (1 year ago)
Based on theory you believe. In replication, if you believe conservative nor the semiconservative, there's no need helicase. But the fact that In transcription, it need halicase to separate that double helix. It's still intra-nucleus. So, helicase can be used in replication nor the transcription. But basically, polymerase is the enzyme for copying mirror that nucleotide.
taraluna01 (1 year ago)
zombot SINGS 354 No, it seperates it for DNA replication. RNA polymerase seperates it for the production of RNA.
Queen Seth (1 year ago)
taraluna01 does helicase separate the dna in transcription
taraluna01 (1 year ago)
zombot SINGS 354 RNA polymerase for the creation of RNA. Helicase separates it for DNA replication.
orts888 (1 year ago)
WHAT CAN I SAY EXCEPT ... THANK YOU!!
Craig Paardekooper (1 year ago)
The narrator sounds like the actor Donald Sutherland
aiidina67 (1 year ago)
Khan Academy is the only reason I’ll be getting a biology degree, haha.
saamerr samer (1 year ago)
Really thank you you helped me alot❤
LadyD0113 (1 year ago)
I love khan academy
mrburns805 (1 year ago)
This dude seriously has a video for everything
Victoria Blair (1 year ago)
so beautiful. great diagrams
Thank you for this tutorial...harpers is quite tedious to understand...this helps a lot
fersiva1 (1 year ago)
Hi Mr Khan, thanks for the explanantion but can you explain on the process on how the cap and tail is added and their purpose in conversion of pre mRNA to mRNA?
Leorenzo Ramon Cruzin (1 year ago)
hi. just a question because i got confused. I am currently reading Harper's Medical Biochemistry. i usually watch your videos when i can't understand the book. According to Harper, the strand that is transcribed or copied into and RNA molecule is referred to as the template strand, and the other DNA strand, the non coding strand, is frequently referred to as the coding strand. I think you interchanged the terms in your video. Can you please clarify these things. Thank you so much!
Indira Nair (8 months ago)
That is exactly what he says in the video.
evan li (1 year ago)
did you pre-draw all those shapes of ribosomes, DNA, and others?!?!?!?! that's insane
Lawson Rodeehk (1 year ago)
This guy is awesome...
Pooja Singh (1 year ago)
thanksssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss
Claire McIntyre (1 year ago)
Sal Khan came to my school a few years ago... it was cool. Except I'm dumb and can't understand anything.
Leyla Abdullayeva (1 year ago)
Hi.  i can a little bit speak Englisch . And very good german but you dont speak german i think. i write to you that you say me if you know it, with help which program i can create biology Pictures like in genetik? i mean Polymerases, Enzme, Proteine, and so on. I wanna to know the name of this programm with help you create the video also. Please send me the download link. Thanks
Sherlon Sinclair (1 year ago)
Your videos are amazing. Cannot possibly get any simpler. Thank you. You're a life saver.
Julia Scheeler (1 year ago)
THANK YOU! Your videos save lives I swear
Rafee Naqvi (1 year ago)
Great video
Atheer I (1 year ago)
5:28 The RNA being transcripted has the same sequence as the coding strand (with the Uracil replacing Thymine), BUT they don't have "the same information". If the coding strand were being transcribed here, it'll give a different RNA sequence, therefore a different order of codons, which eventually gives different amino acids (different protein). So yeah, not the same information =)
kingme. now (1 year ago)
Thank you so much! I'm gonna shed a tear.
therealballer907 (1 year ago)
awesome
jiayixj (1 year ago)
I don't know much about DNA and RNA but I'm only learning this for my crush because he was confused about his essay. Love goes a long way. Good thing I'm a quick learner. Thanks for this video.
The pika RIVERA (1 month ago)
They're probably married by now...
KieSun Wong (1 month ago)
u guys are so bad😂😂😂
The pika RIVERA (2 months ago)
How did it go?
Axel Rmz (3 months ago)
i still want to know if you ended dating
Serine Bts (11 months ago)
Hahahaa
Anirudh Vaiyapuri (2 years ago)
This video was so helpful. It helped me study for my test.
Monira Yusuf (2 years ago)
thanks
fatin qurratul (2 years ago)
thank you
Hussien Jaafar (2 years ago)
I came here for the snRNA and the spliceosome (U , 12456) and he says hes not going into details... is there a particular video
Tamim Ur Rahman (2 years ago)
thank you very much.it helped me a lot for my exam today
Sofia Fernandez (2 years ago)
Nice. This makes so much sense now
M.A Shahid (2 years ago)
RIP for Medved's exam, but this video made it much easier. Thanks and keep it up bro!
fasiha khan (2 years ago)
you make mt life easy, stay blessed
filiciaous (2 years ago)
Are the m RNA being formed are also hydrogen bonded to The template DNA ? and does termination remove the bonding cuz the picture gives a different view
john tindell (2 years ago)
great video
sara aaa (2 years ago)
😍nice
icaa ss (2 years ago)
thanks for the video, such a very good video :)) but just realized that all cromosome or nucleus or enzyme or even protein picture we see in our textbooks or internet just an animation, so it's must be very very complicated in the real life. yet that's all are fascinating things to know about
Summertime yeah (2 years ago)
thanks for my marks khan-academy!
Abdidahir Mohamud (2 years ago)
thanks for the video. it really helped me a lot understanding that
Mary Gonzalez (2 years ago)
Does anyone know if there is a way to get a print out of the diagrams and pictures he shows. The way he explains all the processes with those visuals really help!
Mia Aezaz (2 years ago)
If you go to Khanacademy.com and type the title in the subject search this page will pop and will give you the option to print this lecture. :)
TheLast Cipher (2 years ago)
what playlist is this? thanks :)
Phoenix (2 years ago)
It is like a machine made of Lego.
Tom Davis (2 years ago)
Important to note that in eukaryotes the pre-mRNA processing occurs co-transcriptionally and not post-transcriptionally!
Sharmin Idalis (2 years ago)
I needed this exact video a year ago :'C
Janet Chiang (2 years ago)
it's so weird how you always upload topics about exactly what i'm learning in class!
sleepyduck (2 years ago)
the fact that you can digest all categories of subjects and then teach is mind boggling!
Toks Fawibe (2 years ago)
I know right
Sloth - Gaming (2 years ago)
second comment
RazvanInfo (2 years ago)
Thanks l.

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