oh my god, I couldn't understand this for weeks,I couldn't find any good explanatory videos and you just answered all my questions. I have my biochemistry exam on Monday. thank you

@Leah4sciMCAT

7 жыл бұрын

thank you! glad to help Good luck on Monday!

You are truly gifted when it comes to explaining MCAT content. Thank you!

@Leah4sciMCAT

6 жыл бұрын

Thank you for your kind words!

I can't express how greatfull I am. I've been trying to understand those concepts for weeks with my regular teacher and failed miserably. This explanation was so clear, i finally understood!! Thank you so much!!

@Leah4sciMCAT

2 жыл бұрын

I'm sorry you've had such a struggle with it, but happy that I was able to help you understand!

Excellent job! I totally understand it now. Thank you so much.

@Leah4sciMCAT

8 жыл бұрын

+Ram Palepu You're very welcome! Glad to help

You are just so amazing Leah! You have assisted with turning the cogs in my brains just that little bit more every time!

@Leah4sciMCAT

Жыл бұрын

I'm so glad to hear that I've helped it all click into place!

You explain everything thoroughly! Very good videos. I've recommended this to other students

@Leah4sciMCAT

4 жыл бұрын

Thanks so much, I really appreciate that!

Just found this channel of yours right now! Keep up the good work Leah!!

@Leah4sciMCAT

4 жыл бұрын

Thank you so much!!

Just brilliant. Will be sharing with my past BioChem professor (she loves solid educational videos - knows students all have different learning styles) along with my Pre-Med base. Regret not thoroughly watching through these years ago.

@Leah4sciMCAT

3 жыл бұрын

Please do, and thanks for sharing!

OMG THIS IS AWSOME , I was so confused, you broke it down so so so well!!!!

@Leah4sciMCAT

3 жыл бұрын

Thanks so much!

I'm Really thankful to u for making this tutorial.. finally understood the concept 👍

@Leah4sciMCAT

3 жыл бұрын

Happy to help!

THANK YOU OMG THANK YOU!!! YOU SAVED ME! IM SO GRATEFUL FOR THIS CHANNEL!!!!

@Leah4sciMCAT

3 жыл бұрын

You're welcome! Happy to help!

Saved me once again ❤ thanks for doing what you do!

@Leah4sciMCAT

6 жыл бұрын

You're very welcome! Glad it helped :)

Clear and simple as always, thank you.

@Leah4sciMCAT

5 жыл бұрын

You're very welcome!

Thank you so much Lea! I was struggling with this and got a 503 MCAT, now I ended up getting at 517 and will make a video about how I did it! Thank you so much!

@Leah4sciMCAT

Жыл бұрын

That's fantastic, congratulations! And yes, make that video and help others see how they can reach their goals, too!

Thanks a ton, this concept was troubling me from past 2 days 😇😇😇😇thank you thank you thank you for making it crystal clear.

@Leah4sciMCAT

3 жыл бұрын

Glad it helped! You're very welcome!

What an AWESOME explanation!! you have just lightened my road 😃thank you very much .

@Leah4sciMCAT

Жыл бұрын

You're very welcome, so glad it helped!!

It finally made sense to me while looking at Le Chatelier's principle! Thanks!!!

@Leah4sciMCAT

5 жыл бұрын

Glad the video helped! You're welcome :)

Very clear and concise. Thank you so much!

@Leah4sciMCAT

4 жыл бұрын

You're very welcome!

This is such a good explanation thank you!

@Leah4sciMCAT

4 жыл бұрын

You're very welcome!

Thank you.You made it so simple

@Leah4sciMCAT

7 жыл бұрын

You're welcome

this helped me on a biochem question, thank you

@Leah4sciMCAT

6 жыл бұрын

You're very welcome!

Wow you are amazing. I love it!

@Leah4sciMCAT

7 жыл бұрын

thank you

This is a very good explanation, thank you.

@Leah4sciMCAT

8 жыл бұрын

You're very welcome

very, very helpful! Thank you so much!

@Leah4sciMCAT

6 ай бұрын

You're welcome!

U just saved my life,Thank u

@Leah4sciMCAT

6 жыл бұрын

Glad I could help!

Thank you!!! You are a blessing 😍

@Leah4sciMCAT

5 жыл бұрын

you're welcome!

thank you so much i struggled so much with this topic

@Leah4sciMCAT

7 ай бұрын

It's a tough topic, happy to help!

You are a tremendous teacher.

@Leah4sciMCAT

8 жыл бұрын

thank you

It's so helpful! Thank you!!!

@Leah4sciMCAT

4 жыл бұрын

You're very welcome!

This was great! Thank you!

@Leah4sciMCAT

3 жыл бұрын

You're so welcome!

Really helpful. Thank you!

@Leah4sciMCAT

7 жыл бұрын

Thank you

i love this! Thank you very helpful

@Leah4sciMCAT

4 жыл бұрын

You're so welcome!

you're the best, thanks a lot.

@Leah4sciMCAT

2 жыл бұрын

Awwww, you're so welcome!

I really love you, thanks !!!

@Leah4sciMCAT

7 ай бұрын

You're welcome!

god bless you for this amazing video

@Leah4sciMCAT

7 жыл бұрын

thank you

Very good explaination

@Leah4sciMCAT

2 жыл бұрын

Glad you like it!

I love your explanation, it-s simply made and just enough :=)

@Leah4sciMCAT

4 жыл бұрын

Glad I could help!

Don't understand everything yet but very clear explanation and presentation. Thank You.

@Leah4sciMCAT

2 жыл бұрын

You're very welcome! I'm glad it's helping to clear things up. Go back and rewatch a few more times to help solidify the concepts.

Thx u so much! ❤

@Leah4sciMCAT

Ай бұрын

you're so welcome!

great explanation !! thank you ..

@Leah4sciMCAT

4 жыл бұрын

You're very welcome

You are so great! TY!

@Leah4sciMCAT

3 жыл бұрын

You are so welcome!

Bless you. I understand this well now :)

@Leah4sciMCAT

3 жыл бұрын

Awesome!

I think you may have just saved me from a meltdown. Thanks ;)

@Leah4sciMCAT

2 ай бұрын

Glad I could help keep the meltdown away! Might I suggest booking some time just for yourself for a walk, bath, reading or something else enjoyable where you can completely unplug? Even 20 minutes can make a huge difference.

This concept help me to crack jee advanced 2020 question in seconds ❤❤ 👍 thanks 😊

@Leah4sciMCAT

Ай бұрын

YES to saving time on exam questions!

Omg you are a godsend god bless you

@Leah4sciMCAT

3 жыл бұрын

Wow, thanks!

thanks for a great video!

@Leah4sciMCAT

4 жыл бұрын

You're very welcome!

Thank you so much !

@Leah4sciMCAT

4 жыл бұрын

You're very welcome

Thatssss really helpfullll thanks

@Leah4sciMCAT

6 жыл бұрын

You're very welcome!

Can't thank you enough!

@Leah4sciMCAT

3 жыл бұрын

You're very welcome!

Thankyou very much mam...❤❤💖💖💖

@Leah4sciMCAT

4 жыл бұрын

You're welcome!

bless this video

@Leah4sciMCAT

5 жыл бұрын

Thanks! Good luck to you :)

Great video

@Leah4sciMCAT

6 жыл бұрын

Glad you like it!

Thank you so much

@Leah4sciMCAT

4 жыл бұрын

You're welcome!

thank you so much

@Leah4sciMCAT

6 жыл бұрын

You are welcome!

Your voice is like ASMR, It's relaxing and soothing. I like it a lot, ever think about doing deep sleep mix tapes? 🌝

@Leah4sciMCAT

2 жыл бұрын

hahaha, I haven't, but thanks!

THANKU CUTIE

@Leah4sciMCAT

5 ай бұрын

You're welcome

Fantastic

@Leah4sciMCAT

4 жыл бұрын

Glad you liked it!

omg this makes a ton of sense

@Leah4sciMCAT

3 жыл бұрын

So glad it helped you understand!

GOD BLESS YOU

@Leah4sciMCAT

3 жыл бұрын

Thank you for that!

I have exams in 1hr, wish i saw this much before

@Leah4sciMCAT

4 жыл бұрын

Better late than never?

Hi, thanks for the video. But why at pH13, amino group did not deprotonate?

@Leah4sciMCAT

Жыл бұрын

You're welcome! It did deprotonate. Once it reached the pH of 13, it went from CH3NH3+ to CH3NH2. It lost a proton.

Thanks to this wonderful video! But I still don't understand that why -COOH is still -COOH after protonation and also why CH3NH3+ is still CH3NH3+ after protonation?

@Leah4sciMCAT

5 жыл бұрын

At which specific point in the video?

@mesvetnova7836

4 жыл бұрын

Because -COOH is already a protonated form of carboxyl. It can only be deprotonated now to -COO- (Negatively charged). The -COO can not accept two protons. Just as the -NH3+ can not accept a 4th proton. This is determined by the atoms' valence and number of electrons

Would you recommend memorizing the pKa values for all amino acids?

@Leah4sciMCAT

3 жыл бұрын

Yes and no. Only memorize the estimates I discuss here: leah4sci.com/amino-acid-charge-in-zwitterions-and-isoelectric-point-mcat-tutorial/

Leah, do we need to memorize the pka of the R groups for the Acid Base A Acids for the MCAT? In those the range is +2- -2 correct?

@Leah4sciMCAT

6 жыл бұрын

Yes but not 'exact' values. Remember, on the MCAT close enough is good enough.

@ time 13:15, you wrote glycine as having only one H on the Nitrogen, when it actually has 2 H's. This really confused when you started to count charges...

@ash.toronto31

4 жыл бұрын

Yeah lol

@Leah4sciMCAT

3 жыл бұрын

I’m sorry for the confusion and for the late reply. When neutral and in its de-protonated form, the free amino group of glycine should appear as -NH2. At no point does it actually exist with a single proton. I simply had it appearing that way at the beginning of the problem before I determined if the group was in its protonated (-NH3+) or deprotonated (-NH2) form.

Do you give tutorials about other chapters of Biochemistry?

@Leah4sciMCAT

6 жыл бұрын

For the class or MCAT? My biochem resources are specifically designed for the MCAT. For more help with MCAT biochem, I recommend joining the MCAT study hall. Full details: join.mcatstudyhall.com/

what if you are working with basic amino acid that is already carrying +1 charge?

@Leah4sciMCAT

3 жыл бұрын

I'm sorry, but I don't offer tutoring through KZread comments. For help with questions like this and more, I recommend joining the MCAT Study Hall. For more details visit join.mcatstudyhall.com/ or contact me through my website leah4sci.com/contact/

Why is the amino acid Glycine represented with an NH group instead of an NH2 group, and the COOH group as the COO group?

@Leah4sciMCAT

5 жыл бұрын

I'm sorry but I don't offer tutoring through KZread comments. For help with questions like this and more, I highly recommend joining the MCAT Study Hall. For more details visit join.mcatstudyhall.com/ or contact me through my website leah4sci.com/contact/

Brilliant

@Leah4sciMCAT

5 жыл бұрын

Thanks!

@pfunzonevhusenga8602

5 жыл бұрын

You're welcome. I nailed the test😃😃😃.

@Leah4sciMCAT

5 жыл бұрын

That's amazing! So glad to hear it :)

Am confused, at 15:22, when you deprotonate NH2, shouldn't the charge become -1 instead of neutral?

@Leah4sciMCAT

6 жыл бұрын

NH2 is -1, but RNH2 is neutral due to having 3 bonds and 1 lone pair

Just to clarify, does the pH look at the solution, while the pKa looks at the molecule?

@Leah4sciMCAT

3 жыл бұрын

I think you’ve got the distinction! The pH looks at the concentration of hydrogen ions in solution, while the pKa is a constant for any given molecule. The pKa gives us information about the acidity of a certain proton on the molecule and whether that proton will dissociate or not at the specified pH.

Can someone answer this for me? I thought a molecule that has more H+ ions is BASIC and molecules that don't have that many H+ is acidic? Right or wrong?? for example which is the base and which is the acid of these 2......NaH2PH4 and NaHPO4 and why?

@Leah4sciMCAT

4 жыл бұрын

Have you seen my acid/base series? Leah4sci.com/acidbase

just wanted to clarify, at ph=13, the ph is greater than pka 9.6 of amino group, so amino group should be deprotonated to NH2 from NH3+ right? and thats why you get the charge on the amino group as 0?

@Leah4sciMCAT

5 жыл бұрын

At which specific part of the video are we talking about? (timestamp)

@marissachukwu306

5 жыл бұрын

@@Leah4sciMCAT at time stamp 15:50

@Leah4sciMCAT

5 жыл бұрын

@Marissa Chukwu - correct.

For the last example how does HN got to H3N

@Leah4sciMCAT

7 жыл бұрын

at what time?

@skylarmorrison5162

6 жыл бұрын

Leah4sciMCAT I assume he means at 13:19 when you protonate the amino group

Shouldn't the amine on GLY be de-porotonated at pH 13 because pH>pKa? To go from neutral NH2 to NH??

@Leah4sciMCAT

7 ай бұрын

Yes, the amine will be de-protonated at pH 13. It goes from NH3+ to a neutral NH2. The amine group will never be written as NH (and if it was, it would be negative in charge).

why is carboxylic is charge zero when pH is 1?

@Leah4sciMCAT

3 жыл бұрын

Thanks for asking! A pH of 1 is less than the pKa of the free carboxylic acid group (~2.3) on an amino acid. Because of this, the group will appear in its protonated form as -COOH and is neutral in charge.

I have a question

@Leah4sciMCAT

10 ай бұрын

If you have questions that are specific to the examples in this video, feel free to send them to me along with a time stamp by contacting me through my website at Leah4sci.com/contact

For pH of 13 for glycine, shouldnt the amino group be deprotonated and not protonated?

@Leah4sciMCAT

5 жыл бұрын

at which specific point in the video?

@acepokemontrainer1

4 жыл бұрын

It is already deprotonated. Instead of H3N+, it has deprotonated at pH 13 to become H2N like she has drawn.

So you said that the neutral form cannot exist, but that the zwitterion is the neutral form and then you claimed that it is the most common form, please elaborate I'm confused

@Leah4sciMCAT

3 жыл бұрын

I apologize for the confusion. The amine and carboxyl groups cannot both appear in their neutral form at the same time. In nature, we most commonly find amino acids as a zwitterion where the amine holds a positive charge and the carboxyl hold a negative charge. Overall, these two charges cancel out, creating a net neutral charge for the molecule. The idea is that neither group is neutral by itself, but together they form a net neutral molecule.

i was confident until you did the example with glycine and misdrew it... it got me so confused during the entire example and now I'm just really anxious and confused :( ... please fix this....

@Leah4sciMCAT

5 жыл бұрын

at which point of the video are we referring to?

THANK YOUUU!! I finally understood what to do if pKa is equal to pH! God bless you (//>^

@Leah4sciMCAT

3 жыл бұрын

You're very welcome! I'm so glad to help you understand!

At pH 7.5 does glycine exist as a zwitterion? And at pH 10.5 does it possess a negative charge? I need to be sure

@Leah4sciMCAT

10 ай бұрын

If you watch the example that begins around the 13:00 min mark, you'll see me walk through the various forms of glycine at different pH values. At any pH between 2.3 and 9.6, the molecule exists as a zwitterion. At any pH above 9.6, it exists with a -1 charge.

@user-gl6xg1zr1w

10 ай бұрын

Thank you ma'am

at ph 13 why did the amine group get protanated ... is should be deprotonated ryt ? bcoz the surrounding has got less H+ ion they y did the NH was protonated ....im confused ..

@Leah4sciMCAT

8 жыл бұрын

+gandhi manikandan what point in the video?

@gandhimanikandan2490

8 жыл бұрын

+Leah4sciMCAT mam will the ammino acids we take in food are always in zwitter form ie amine is NH3 + and carboxyl group is coo - ??

@gandhimanikandan2490

8 жыл бұрын

+Leah4sciMCAT just nw watched ur vid again ..nw its clear just pls clarify the doubt above ...ie protein we eat has their ammino acids in zwitter form ? is it ?

Why do you have the Amine Group as "H2N" at the beginning of the video, but as "HN" at the end of the video?

@Leah4sciMCAT

8 жыл бұрын

Not sure I understand where you're seeing HN

@anashchowdhry6879

7 жыл бұрын

on the amino group for the last exmaple

@acepokemontrainer1

4 жыл бұрын

She drew H(space)N so that she eventually fills in all the numbers as she showed the specific pH values. Depending on the pH, the amino group is protonated or deprotonated, and she shows that with her drawings.

I'm confused. Ka is a constant for any given acid, right? So how can it be proportional to the hydrogen concentration? Constants aren't proportional to things! Ahh!

@Leah4sciMCAT

3 жыл бұрын

Sorry you're so confused; let's get things cleared up for you. Yes, Ka is a constant for any given acid. Maybe it would be better to say that Ka is proportional to the ratio of [H+]/[HA]. It stands to reason that acids which produce a higher quantity of H+ per unit of acid would have greater Ka values (and thus be more acidic). So even though the Ka doesn’t change for a given acid, it is variable between different acids based on how much H+ that particular acid produces.

at 12:47, would it be NH2 instead of NH? and O- instead of O? I'm just a bit confused on what the starting molecule of glycine looks like.

@monicabarsoum3434

5 жыл бұрын

I was confused about this too! idk why she didn't explain this or make a note about it at least:(

@kousalyadevi5209

5 жыл бұрын

Have the starting material as NH2 and COOH.. Remember NH2 can't be deprotonated further (to NH) and COOH can't be protonated further.

@Leah4sciMCAT

3 жыл бұрын

I’m sorry for the confusion and for the late reply. At no point does glycine actually exist with a single proton on the nitrogen or with an uncharged, de-protonated oxygen on the carboxy group. I simply had it appearing that way before I determined if either group was in its protonated or deprotonated form. There really is no “starting molecule” of glycine. It will exist at different charge states, depending on the pH of the surrounding solution. We always have to consider the pH before determining how glycine will appear.

LET HER COOK!!! wow, you just earned a subsciber!

@Leah4sciMCAT

Жыл бұрын

Yay! Thanks so much for watching and subscribing! Glad you liked the video.

Excellent job Leah, thanks a lot! Just one question, regarding the quiz on your website: In part 3, we are asked to find the charge of Cys at PH = 4. Pka values for Cys are as follows: (Pka(COOH):1,71, Pka (NH2): 10,78, Pka(R): 8,33 ). The solution suggests change 0 for the side chain. Could you please explain this to me? I would expect to see +1 for the side chain and not zero, as PH is much less than the Pka for side chain, which means that the side chain should get protonated (conveting to S2H+ from SH). Am I missing something? All help would be appreciated.

@Leah4sciMCAT

2 жыл бұрын

You're very welcome! Since I don't offer tutoring over social media, I would first suggest you use the download link at the bottom of the practice quiz to access the PDF quiz solutions. If you would like a more detailed explanation, I recommend joining the MCAT Study Hall. For more details visit join.mcatstudyhall.com/ or contact me through my website leah4sci.com/contact/

It's not log, it's lg.

@Leah4sciMCAT

3 жыл бұрын

In the Henderson-Hasselbalch equation, we use a logarithm with a base of 10 which is abbreviated “log”.

@zarakristen2967

3 жыл бұрын

Commonly used as log

I don’t know but why you are so concerned about acetic acid !!! Where is the amino acid in this whole lecture!!!!

@Leah4sciMCAT

3 жыл бұрын

An amino acid is an organic compound that contains both amine and carboxylic acid functional groups. In this video, I first look at acetic acid and methylammonium, as examples of how those same functional groups would behave on their own at various pH values. Then, to apply that knowledge, I turn to the example of the amino acid glycine at 12:37 to explain how these functional groups would function together within the same molecule at various pH values.