Lac Operon & Gene Regulation Made Easy - Best Explanation

JOIN OUR CHANNEL
Get the LECTURE HANDOUTS & FLASHCARDS from this topic :

CLICK THE JOIN BUTTON
Or

The lac operon (lactose operon) is an operon required for the transport and metabolism of lactose in Escherichia coli and many other enteric bacteria. Although glucose is the preferred carbon source for most bacteria, the lac operon allows for the effective digestion of lactose when glucose is not available through the activity of beta-galactosidase.

Gene regulation of the lac operon was the first genetic regulatory mechanism to be understood clearly, so it has become a foremost example of prokaryotic gene regulation. It is often discussed in introductory molecular and cellular biology classes for this reason. This lactose metabolism system was used by François Jacob and Jacques Monod to determine how a biological cell knows which enzyme to synthesize. Their work on the lac operon won them the Nobel Prize in Physiology in 1965.

E. coli encounters many different sugars in its environment. These sugars, such as lactose and glucose, require different enzymes for their metabolism. Three of the enzymes for lactose metabolism are grouped in the lac operon: lacZ, lacY, and lacA (Figure 12.2). LacZ encodes an enzyme called β-galactosidase, which digests lactose into its two constituent sugars: glucose and galactose. lacY is a permease that helps to transfer lactose into the cell. Finally, lacA is a trans-acetylase; the relevance of which in lactose metabolism is not entirely clear. Transcription of the lac operon normally occurs only when lactose is available for it to digest. Presumably, this avoids wasting energy in the synthesis of enzymes for which no substrate is present. A single mRNA transcript includes all three enzyme-coding sequences and is called polycistronic. A cistron is equivalent to a gene.

A second aspect of lac operon regulation is conferred by a trans-factor called cAMP binding protein (CAP, Figure 12.5). CAP is another example of an allosterically regulated trans-factor. Only when the CAP protein is bound to cAMP can another part of the protein bind to a specific cis-element within the lac promoter called the CAP binding sequence (CBS). CBS is located very close to the promoter (P). When CAP is bound to at CBS, RNA polymerase is better able to bind to the promoter and initiate transcription. Thus, the presence of cAMP ultimately leads to a further increase in lac operon transcription.

[lavouche]

Watching this, I realized the concept isn't even difficult. The textbooks and useless teachers make it hard. Thanks for making this understandable and logical! So happy I found your video.

[jitendrapatil]

i can't imagine how much time and hardwork you put in making your videos, from animation to integrating all the concept for a topic. A huge thumbs up for your work buddy :-).

[i-ls--sreyagayathrirapet]

I think the person who teaches this concept had worked a lot to make us understand by relevant pictures a big round of applause and thanks should be said to him. Simple clear and understanding explanation. 👍

[laibaimtiaz]

I just cant have words to explain how much these lectures get me through my end exam times like its been 3 years to this video lecture but it still helping alot of confused students just like me even in 2023. Great respect to you.
The topics which my uni professors made so hard for us but you made it so easy to memorize via your incredibly amazing animations, just love it.

[jalenandrew]

You honestly deserve a Nobel prize for this.

[amolpreetkaursaini]

I am a first year PhD student and I can finally say that my concepts are clear after watching your videos . Thank you so much :)

[jothilakshmichettiar]

This was actually the best explanation!!!

[Incoganon]

Learned more in a 20 minute video than a 50 slide lecture. Thank you very much

[everalves]

This video 100% deserves my like and a comment. An incredible amount of valuable details, and it is so easy to follow along when you have some knowledge of the topic. Best 25 minutes spent on ever! Four hours in class did not provide 1% of what this video gave me! Amazing job! Thank you so much for doing that.

[yusratariq]

Bhai bhai bhai. Amazingly explained. I was thinking how much difficult it would be to animate all of this. So, thank you!

[europaxyz]

Keep on making this type of videos, it's really worthful to watch and completely understanding the whole thing without pseudo imagination and confusions.

[avijitbhadury]

The best explanation of this topic in YouTube. Thumbs up for the immense effort. The two mistakes I found was that
1. You once said DNA polymerase in place of RNA polymerase.
2.The I gene stands for inhibitor, and not, as you said, "inducer". The substrate of the enzyme beta-galactosidase, i.e.lactose or allolactose is the inducer.

[mikeiwanicki]

Best explanation I could find. The textbook could never explain this so simply. Thanks!

[thenoobksa]

my final biology exam EVER for high school is in two weeks and only NOW do I understand gene regulation... thank you so much for this video, you're an absolute lifesaver!!

[sampsonetienoasuquo]

It took a whole school section to understand this mechanism. Thank you for helping me out. This video is a life server 🎉🎉🎉🎉

[pushpalathaandra]

👍I'm an Assistant Professor in Government Institution. I really liked your videos. They are easy to understand. I share your videos to my students. They are quite useful.

[oluwatosinodukoya]

Well done. This is a wonderful breakdown of this topic. I love the way you linked the concepts together. You did a wonderful job. Thumbs up.

[theresamumba]

on my own, I was failing to understand Gene regulation but thanks to you, I am fully equipped.

[surabhign]

i read the text for 6 times and didnt get the concept. u made it so easy to understand and learn. thank you!!

[nadeekakumudu]

Because of you, I will be able to pass my exam. these were not understood earlier. THANK YOU so much and keep up the good work.