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Lac operon

1931 ratings | 321068 views
Overview of gene regulation in the Lac operon. Discussion of CAP, cAMP, lac repressor and allolactose in regulation of lac operon.
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Text Comments (105)
Zahra Khalid (1 day ago)
But prokaryotic cells do not have CAP sites in their operons? Isn't it only found in eukaryotic genes?
jojibot (14 days ago)
Learned more in 1 video than an entire week of class
Asim lamichhane (1 month ago)
you just compressed 3 of my agonizing lectures into 11 minutes and now i've understood it all. You are my hero.
Anichu (1 month ago)
Thank you so so so much, I didn't understand the Lac operon until now. You saved me!!!
FALISHA E. (2 months ago)
thank you so much. it helps a lot♥️
Srishti Gupta (3 months ago)
This is the first time I actually completely understood the chapter of molecular inheritance, thank you so much khan academy
kuldeep dinkar (3 months ago)
you did not mention lac I (regulatory gene). Youhave confused me.
Albin Kamei (3 months ago)
Gaaawwwwdddddd..... this is just made my life sooo much easier...!!!!!
Mohamed Atta (3 months ago)
Thank you so much Sir !
EhsanAli Maknojiya (4 months ago)
Thnx man....u r great
Silvan Aban (4 months ago)
Thank you!
Zera Najwa (4 months ago)
Thankyou so much! I have paper tomorrow and watching your video really helps me to understand the concept. You're my savior
Lusia Hemmings (4 months ago)
Thank you so much for helping me understand how Lac operon works!! I didn't even understand the mechanism when my professor told us in my native language
Kimberly H (4 months ago)
Wow! I've skipped over this many times. Thanks for making is so easy to understand!
Yaarit Hanan (5 months ago)
Thank you very much! It's really helpful!!!
ISHRATH KHADEER (5 months ago)
Thanks a lot...
ISHRATH KHADEER (5 months ago)
Thanks a lot...
ISHRATH KHADEER (5 months ago)
Thanks a lot...
Ella Reshef (5 months ago)
Awesome explanation and has made life so much easier, thank you!!
Racheal Cameron (6 months ago)
thank you I'm studying for Micro final and this helped a lot
Shanzay (6 months ago)
You are seriously the best!!!
Shire Mahdi (7 months ago)
I'm intolerant too
blew 3-1lead (8 months ago)
also Sal should mention that the binding of cAMP works by improving the efficiency of polymerase binding. Great video though.
Miguel Gomes (8 months ago)
Thanks a lot for this video and also the one on tryptophan. I was understanding nothing about this genetic expression regulation systems, and you made it very clear, I feel I completely got it. You explain very well and the video also helps So thanks and keep it up :DD
Reni (8 months ago)
Thank you 🤓🤓 It was a huge help 🤓🤓
Kübra Bekar (8 months ago)
God bless you
aniq mirza (8 months ago)
thanks you so much !
Jacqueline Labovitz (9 months ago)
awesome!
Garrysingz01 (10 months ago)
Whats the basic function of lactose in the functioning of this operon
awesomepawesomesocks (10 months ago)
just FYI for anyone thinking this, EUKARYOTES DONT HAVE OPERONS..... ONLY PROKARYOTES therefore we all lack the lac operon, but ecoli in our body has them
Paris Coroneos (17 days ago)
lmao u could almost say we lac the operon lmao
michelle le (10 months ago)
sal from khan academy makes me feel safe
Moeen Khan (10 months ago)
Khan da real MVP
To sum up, when there is no glucose and lactose is present, the catabolite activator protein with high cAMP will bind to the CAP site, therefore enabling transcription(the body needs energy) while if there is glucose and lactose, the system prefers glucose over lactose and will not transcribe. The catabolite activator protein will not bind since it already has a lot of cAMP, here the lac operon acts as an regulatory sequence of gene responsible for protein synthesis. The glucose inhibits the production of cAMP(cAMP are derivatives of ATP) which makes sense since there is already a lot of energy.
All_in_ 7 (10 months ago)
THANK YOU SOOOOOOOOOOO MUCH
faucher Louise (11 months ago)
this video is just perfect to understand ! just amazing ! hope you'll continue these kind of videos thank you so much
Alexis Nguyen (11 months ago)
I've watched so many of your videos to save me from failing. At this point, I owe you my college tuition.
TheOlowal (11 months ago)
God bless Khan Academy. A lots of people become doctor because of you. Keep it up Professor 🤓
Jedi 511 (11 months ago)
Super helpful as always!
陆东昊 (11 months ago)
you are so perfect!
Putu Cri (11 months ago)
wow,, it helps me so much,, thank you!!
Sharon Sardar (1 year ago)
Amazing set of videos... easy to understand and very helpful...
Laksika Suksawat (1 year ago)
This is SAVING my life. Thank you so much.
sukhpreet singh (1 year ago)
makes me say WOW
Simran Singh (1 year ago)
thx very much salman khan even you are a star man
Jahnvi Sachan (1 year ago)
Amazing video guys. Thanks a lot for the help.
tayma ateyah (1 year ago)
FINALLY!!! I really needed to understand this, thank you!!!! <3 <3
Sir Thugbert (1 year ago)
I am a MS2. This video still teaches it better than my biochem or microbio prof. Thank you!
Shubham Singh (1 year ago)
The explanation is very good. It helps me a lot nunderstanding the topic correctly. Thanks Khan Academy
Videos (1 year ago)
Great video. Thanks.
Arshad Ahmed (1 year ago)
so the LacY is responsible to transport lactose through cell membrane, its an inducible system, and LacY protein itself cant transcribe if there is no lactose, so how come lactose entered first time when there is no LacY protein. is there any other protein that pumps the lactose inside cells (initially)?
Arshad Ahmed (1 year ago)
this discussion is helpful, check http://sandwalk.blogspot.com/2008/10/lactose-paradox.html
TheWhiplash18 (1 year ago)
Lactose is able to diffuse through the cell membrane slowly without the transport protein. When the lac operon is activated, the transport protein is produced and the lactose is able to enter the cell faster.
dody alname (1 year ago)
thank you for this video 💚💚💚
Deemah Al-bahrani (1 year ago)
Man! this is AMAZING and much more helpful than my professor and books
Elsie Estevez (1 year ago)
How does it return to its default state?
MJ (1 year ago)
Thank you so much, it was really helpful.
Reyna (1 year ago)
I love this man. I love his personality and the fact that this stuff is less boring and more easy to understand now.
Latesha Gibson (1 year ago)
Omgggg this is soooo helpful!!
Nelson (1 year ago)
Just wondering why the default position is off if it is a repressible gene?? Then I guess it is an inducible rather than repressible gene.
Nelson The default position is off because your body does not want to waste energy, therefore it won't transcribe if there is no lactose or glucose present. The operon that needs lactose in order to function is said inducible. This stands in contrast with the trp operon which is said to be repressible(high tryptophan=no transcription).
baldy hardnut (1 year ago)
Cheers Khan I went through a couple of vids until I hit this one to understand how glucose is managed in lac operon pathways.
Cori Barajas (1 year ago)
Omg so helpful! Thank you!
mel (1 year ago)
wow super helpful!!! thank you!
Shruti Nair (1 year ago)
Seriously u are heavenly teachinggg... thank u so so so very much ! All the best ,keep helping us ]
Kim Wirth (1 year ago)
You guys are great. Thanks!
Anthony Lebario (1 year ago)
I'm assuming CAP is the same/similar to cAMP receptor protein (CRP)?
Abdala Abdullahi (9 months ago)
Reyna no CAP is an activator mean while cAMP is an inducer
Sara N (11 months ago)
Yes, CAP is the older terminology used for CRP (cAMP Receptor Protein). It is 2 names for the same thing.
Reyna (1 year ago)
Anthony Lebario cAMP is bound to the CRP protein.
bushra syed (1 year ago)
is CAP site the regulatory gene???
Lisa Stephan (1 year ago)
OMG. Thank you so much! I can't believe how much better you are explaining that then my uni lecturer! I mean even in english (I am from Germany) I can easily understand what u are talking about. You saved me. Hopefully trp will be as good as this video. =) Keep going'! Best Regards
Thinklit 23 (1 year ago)
Thank You Khan Academy, What took Hours of Learning you taught in 11 minutes, Thanks!
Cara Kaminski (1 year ago)
Why can't professors explain this as easily?
yuzu yuzu hanyu (1 year ago)
This saved me, thanks!
fasiha khan (1 year ago)
superb, I m Ms genetics student and having this topic in molecular genetics, very impressive. Stay blessed
Dania Hasan (1 year ago)
this is AMAZING ! thank you so much and keep please don't stop posting vedioes
joohnny kuz (1 year ago)
What about high glucose and no lactose? No transcription?
Ashok Kadariya (1 year ago)
High glucose= low cAMP= no binding to CAP cites= No bending of DNA and RNA polymerase to associate with the promoter=NO transcription Again, No lactose= No isomers(Allolactose)= Lac repressor keep binding to the operator= No RNA polymerase binding with promoter= No transcription
Jack Coops (1 year ago)
Which mRNA's are involved in LCT gene expression?
joohnny kuz (1 year ago)
+Aaron McConeghey Yeah just had an exam and aced this entire segment, I remember one of the last question talking about, in which scenario would the lac operon transcribe the most. It was low glucose and lactose. Lactose will subdue the repressor and low glucose would call for CAMP.
Aaron McConeghey (1 year ago)
Correct. If there's no lactose, there's also no allolactose present to bind to the lac repressor. We get Basal Level Transcription - which is the lowest possible rate (although still more than 'no transcription'). https://youtu.be/LuOaEe89_HE?t=5m59s
Chidinma Osuagwu (1 year ago)
can not believe how much more helpful you are than my professor. god.
김소형 (2 months ago)
Chidinma Osuagwu same you saved my grades thanks god
asdfghjkl (2 years ago)
will lac operon transcription still occur if glucose and lactose are present in the media? The operon prefers glucose as their energy source so wouldn't the lac operon be repressed? Can anyone confirm?
Devon Lundine (1 year ago)
When lactose and glucose are both present in the media, the lac operon is transcribed, but at very low levels (basal transcription).
jatin jaggi (2 years ago)
sir there are no words to say for your effortless work I have so much respect fr u KEEP INSPIRING !!
Usman Shami (2 years ago)
I love this guy. Whoever is the narrator. Amazing explanation. He just made lipincott so easy. Khan Academy is the best. Always listen to it literally for every topic
Ashby M (11 months ago)
Usman Shami his name is Sal Khan
cara9797 (2 years ago)
omg this is a life saver
Pranav Sood (2 years ago)
So Sal lacs the operon......
baldy hardnut (1 year ago)
Ru gay?
Andrew H (2 years ago)
This helps me understand the LAC OPERON very well without bordering reading whole Campbell 10th edition textbook.
Elios Sgouros (6 months ago)
Hey I'm resting my arm on that book right this second
Trần Thùy Dương (1 year ago)
I feel ya bro =)))) 2016-2017 students still have the sameeee problem
Cookie King (2 years ago)
So you lack the lac operon
Manectric7 (5 months ago)
That means we all lack the lac operon
Dana Raz (8 months ago)
well, bacialy, no... the operon found only in prokaryotic...
lol good one!
Sabrina Monstar (2 years ago)
I like cheese.
Alejandra Cabezas (2 years ago)
cuarta
jake (2 years ago)
Would have been useful about 7 hours ago before my exam, haha great video as always!
Emily Aloise (2 years ago)
second
iStandByi (2 years ago)
FIRST!

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