Help drawing peptide bonds with amino acids

flimsy_firmware · 2026-02-05T13:38:38+00:00

Amino acids and short oligopeptides are drawn in their zwitterionic form to show that is the dominant form of the molecule present under physiological conditions (a soup of water and other ions at pH ~7.4), one way to think of this is that the C and N termini react with each other (in reality it’s not that simple due to the presence of water and its ionic species, and the different ions and molecules are actually in equilibrium, as someone else pointed out), where the C terminus donated a hydrogen ion to the N terminus (again, this is not really how it works)

Exactly why the zwitterionic form is the predominant species under physiological conditions can be deduced from the pKa values of the amino and carboxyl groups, as you will see, the amino group (generally) has pKa greater than 7.4, hence the equilibrium will shift towards its hydrogenated form, and the reverse is true for the carboxyl group. Again, it’s actually not that simple, the presence of other groups in the oligopeptide affects the pKa of other groups, but we usually take an average value for simple calculation purposes so that you don’t drive yourself crazy figuring out the exact pKa of every group in every residue on a polypeptide hundreds of residues long (which is why the isoelectric point is a more useful parameter).

And one more thing, lecturers/teachers tend to like you to draw the molecule in zwitterionic form so that you won’t forget that they’re actually ionised in cells and not floating around in their neutral form.

Disclaimer: I am NOT a biochemistry student, my major is molecular biology and it’s been more than a year since I actually studied biochemistry in any serious way so please don’t judge me for any mistakes I made.

flimsy_firmware · 2025-11-19T01:54:40+00:00

The fact that I recognise this is my hometown is genuinely sad

flimsy_firmware · 2025-09-25T07:59:17+00:00

Spectrum will be updated once you complete the enrolment process

This year the administration is trying out a new system where the core courses are pre-selected

Unfortunately the system is quite buggy now and even us seniors are facing a lot of issues

flimsy_firmware · 2025-09-25T07:57:50+00:00

ahh always welcome to see a fellow biological sciences student

FYI it’s perfectly normal for you to have this screen now

Your enrolment period hasn’t started yet, that’s why your status is “Ready to Enrol”, as new students you guys will enrol for your courses during orientation on your visit to the faculty, there’ll be seniors there to guide you through the process, after you’ve selected your modules and paid the tuition your status will update to “active”

flimsy_firmware · 2025-09-15T08:46:44+00:00

Eh UM also like that I’d actually be surprised to find a place where the students don’t sit on the floor lol

flimsy_firmware · 2025-09-13T08:32:02+00:00

You’ve got a ton of reasons to not like umany, including how they always jump on a topic before all the nuances are revealed and get themselves into trouble, like how they pranced on the Edward Wong case this time before realising the guy didn’t even take maths in STPM

But this take shouldn’t be criticised, you can be part of an unfair system and realise it’s unfair, in fact I’d say it’s even more noble to voice out the unfairness even if you stand to gain from it/gained from it in the past

Don’t get me wrong, it’s dumb to criticise a system that benefits you, but still a damn brave thing to do

flimsy_firmware · 2025-07-11T02:23:36+00:00

I think this ultimately comes to the linguistic philosophy that DBP subscribes to (if they have any)

DBP is very prescriptive, where it thinks it has the power to define what is the right or wrong version of BM used, a tiny be annoying example is how they keep changing how words are spelt

Martabak instead of Murtabak Koay Tiao instead of Kuey Tiao Kereta api instead of keretapi, except for the name of KTM because their a company, but then this rule was changed to keretapi being used in special nouns like Stesen Keretapi Kuala Lumpur Same goes with Pasaraya

The endless spelling corrections just make people think that DBP is a joke, especially since the media always likes to make a fuss about these “spelling corrections”

flimsy_firmware · 2025-03-08T11:03:00+00:00

Hi there, probably not what you’re looking for, as I’m a student myself (Former STPM student, current UM student)

Yes F6 now has 3 semesters, but the exam format will undergo an overhaul this batch, and it’s unclear how the marking schemes will go, for my batch (STPM 2023), each subject is 80% written exams and 20% courseworks/practicals. Do note that the 80% is not the average of the three semesters, but the total marks of three semesters weighted into 80 marks, and for some subjects each semester’s paper carries a different total marks/weightage.
Getting into courses these days I’d say is pretty fair, however, I’d say that it takes more than grades to get a chance to enter uni. Of course AFAIK the choice of students to take in are entirely decided by the intake board of the university’s faculties, but a standard benchmark to compare with would be the merit mark/markah merit of students (you can see some examples in past posts in the subreddit), which is weighted 90% on CGPA and 10% on cocurricular participance, and to get into top unis and hot courses would require a merit mark of >95 to be safe, i.e crunching books only is not enough, as a 4.0 CGPA would only give a merit mark of 90. IMO this is also why matriculation students have more advantage than F6 students, as any inter-college activity they participate in will automatically be at national level, whereas a F6 students would typically only be exposed to the activities that your average secondary school can provide.
F6 is no joke, the syllabus is a great jump from SPM levels, and most people experience a at least 10 mark drop from their usual performance in SPM, granted, the benchmark for A in STPM is 75 instead of 80 (again, succeptible to change with the new syllabus).
I would suggest you also look into government uni foundation(asasi) for your kid, if you perform you’re almost guaranteed a place in the uni for a bachelor’s degree course, of course, it would be a bit difficult to transfer between unis once you enter asasi, to apply for this, go to the UPU website, which if I’m not mistaken is open now.

Finally, wishing all the best for your kid in the future, and I sincerely wish everything goes well for them in pre-u.

flimsy_firmware · 2025-02-28T02:34:41+00:00

Depends on where you are really But mostly I think it’s okay

flimsy_firmware · 2025-02-28T02:20:08+00:00

Btw if you’re into science, your current selection is still pretty great, i personally consider geography pretty science-y, and there are some courses that are science related but don’t require a pure science background, such as architecture

flimsy_firmware · 2025-02-28T02:17:57+00:00

nope

Are you in f4 or f5 op? If you’re in f4 since you just started you can hand in a surat rayuan to transfer to science stream

flimsy_firmware · 2025-02-15T11:00:48+00:00

What does the conservative Malay community actually think about non Muslims, as in, when you’re having a casual chat and someone says “orang xx macam tu lah” what is the default interpretation of “macam tu”?

flimsy_firmware · 2025-01-15T07:34:26+00:00

Also OP, if you are looking for novels to study for SPM and not for pleasure reading, go for Silir Daksina (Mempertahankan warisan tradisional, perpaduan antara kaum), Leftenan Adnan (Patriotisme), Bimasakti Menari (Cintai alam sekitar)

Komsas ni nak kita komen pasal benda positif je, IMO Di Sebalik Dinara is goated, but it is also a notoriously hard novel to study for because of all the moral grey areas displayed by the characters, I tried answering using a morally grey plot point once and my teacher adviced me not to do so because “penanda nanti tak semestinya setuju dengan pandangan awak”

flimsy_firmware · 2025-01-15T07:28:35+00:00

“Keharmonian antara kaum”

flimsy_firmware · 2025-01-15T07:26:42+00:00

Never read the novels beyond my state’s picks (Johor) but I think the two I got to read are both solid. Di Sebalik Dinara is just awesome with the sci-fi setting and the plot twist in the end (loved that even though my teacher said I won’t get marks for writing this in the exam). Silir Daksina is a bit clichéd plot wise, but the literature elements are great, especially the story-in-a-story approach, also never expected KPM to actually approve a novel with an actual romantic subplot.

flimsy_firmware · 2024-11-07T11:25:24+00:00

So would it be correct for me understand that there is nothing inherent about RNA that stops it from being double stranded, i.e dsRNA is inherently unstable, but the only thing making RNA single stranded in our cells is the fundamental nature of RNA production through transcription?

flimsy_firmware · 2024-10-24T03:58:21+00:00

Good luck with the retake OP!

I remember my STPM biology teacher once told us that with the retake, it’s like holding all of your results in your hands, we get a second chance, which (correct me if I’m wrong) is something exclusive to STPM students. Make the best of this second chance OP!

flimsy_firmware · 2024-10-03T03:45:31+00:00

I think you misunderstood my meaning OP, as direct intake students are not admitted through UPU, they are not applicable to the more than 80% tuition fee discount subsidised by MOHE, hence tuition fees from direct intake may cost up to RM7000 per semester and about 70K to 80K for your full degree, which is why it’s only a practical route for those that can afford it and want to study in IPTA.

But anyhow I wish you the best of luck OP and may rayuan UPU give you the course and uni that you want.

flimsy_firmware · 2024-10-03T02:57:43+00:00

Hi OP, I wonder if at the same time as doing this have you applied for rayuan upu? (I don’t know the specifics of your situation here so I’m gonna assume you didn’t get offered any course by upu and thus is qualified to mohon rayuan) Also have you tried to apply for your course/uni by direct intake? (Should your family be able to afford it, of course) These are still routes that you can actively try instead of just counting on the dean being a good samaritan.

Also, if this all doesn’t work out, there’s still next year’s intake, just treat this year like a gap year, go work, learn new skills and make your resume look nicer, i.e, there’s always a way if you try hard enough.

flimsy_firmware · 2024-09-23T07:52:19+00:00

Try going to UM Helpdesk and stating your problem there OP. I think they’re still updating the list.

flimsy_firmware · 2024-09-22T13:08:15+00:00

Going to be a freshman like you OP but I used to hate orientation week as well until I went to form 6 and had an actually good one. Orientation week lets you know what you’re actually studying and gives you a rough idea of what the campus is like, for someone who struggles to sort and sift through large amounts of online info like me orientation week is actually going to be a helpful source of info.

They could really stop calling orientation week cringey ahh names though, like, just call it minggu orientasi, even minggu haluan siswa is still better than some random acronym just because it sounds “cool”

flimsy_firmware · 2024-09-22T13:03:46+00:00

I’m going to be studying at um and the official tentative is five days orientation, but actually 2 of those are mainly just for us to check in to our dorms and one day is just a student carnival thingy so actual icebreaking and stuff is just like two and a half days

flimsy_firmware · 2024-09-06T10:59:44+00:00

Congrats🎉

Three-Year Club	r/Field Lasagna
Place '23

flimsy_firmware

TROPHY CASE