Also greetings from Germany. I'm taking Biochemistry in German (not my first language) and your videos really are a life-saver for the concepts that are harder for me to translate. Much appreciated!
I'm writing a comment here for my own reference in the future. No other places to take notes right now. ' Aldehydes can be oxidized into carboxylic acids, which are also formally called aldonic acid. Because maltose and lactose have 1,4-glycosidic bonds (regardless of their alpha or beta conformations), this means that there is still at least one anomeric carbon capable of opening up into the open-chain aldehyde form (also known as mutarotation). Thus, it is called a reducing agent (reducing sugar). And sucrose is not a reducing sugar because the anomeric carbons are both taken up in the alpha-1,2-glycosidic linkage, meaning that there's no chance for aldose formation....? Isn't beta-D-fructose a ketose though? I did a bit of googling and I found that ketose sugars can tautomerize (rearranging bonds) resulting in an (enol), a double bond and -OH group. So ketoses also act as reducing sugars by becoming aldoses until a "keto-enol" shift under basic conditions...interesting. aldoses = open chain carbohydrates with aldehyde as their oxidized functional group ketoses = open chain carbon hydrates with ketone hemiacetal = cyclic rings due to intramolecular reactions between an nucleophilic hydoxl group and electrophilic carbonyl carbon in an aldose
In fructose, hydroxyl group in C3 is in the opposite direction as others, as a result, OH resides inside the pentagon ring in C3. But when it becomes Sucrose, i noticed that hydroxyl group is inside of pentagon in C4. Can you please explain why?
Since it's a beta anomer, the OH on C-2 has to face the same side of ring as the CH2OH on C-5. The OH on C-4 also has to face the opposite side of ring as the OH on C-3. That leaves only one option, C3-OH facing down and C4-OH facing up.
A simpler way to think about it is to draw the furanose from the Fischer as you normally would, then flip it left to right (place the paper upside down). All top substituents go to the bottom and vice-versa.
The reason the maltose C1 anomeric carbon is designated alpha is that it's former hydroxyl group, which is now the glycosidic O bond linking the two monsaccharides, is cis to (on the same side of the ring) as the 4th carbon's hydoxyl group. The lecturer was wrong when he referenced it to the position of the CH2OH group attached to carbon no. 5. That group is trans to the glycosidic O bond. The alpha/beta designations refer to the positions of the anomeric hydroxyl group and the hydroxyl group oxygen which is directly bound to the highest numbered chiral carbon in the ring.
My MCAT book defines it the same way he does, as the relationship with respect to the CH2OH (the 5th carbon). If it’s trans or pointing down, it’s alpha and if it’s cis or pointing up with respect to the 5th carbon then it’s beta-anomeric
@@brittopereppadan5503 Please explain how can a single natural disaccharide [Lactose] can have two different monomer units [alpha & beta Glucose] ..and still be called Lactose Thanks
To determine whether the glycosidic linkage is alpha or beta between two monosaccharides ( the first one for Beta and the second one for Alpha) , are we just looking at the first monosaccharide which is beta? (referring to lactose) :) Thanks!
6. If a disaccharide is formed through a (1-> β4) glycosidic bond, it means that ________. A. neither the first nor the second monosaccharide unit needs to be in the β-form B. both monosaccharide units need to be in the β-form C. only the first monosaccharide unit needs to be in the β-form D. None of the above is correct. Can someone help me with this qn?? )):
greetings from Germany I understood so much more in your Video than I understood in German videos or in class thank you so much🙌
nicole S. Hallo, Kamerad! 😂
Also greetings from Germany. I'm taking Biochemistry in German (not my first language) and your videos really are a life-saver for the concepts that are harder for me to translate. Much appreciated!
Great lecture! Made me really understand the structure rather than basically memorizing them without any context
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I'm writing a comment here for my own reference in the future. No other places to take notes right now. '
Aldehydes can be oxidized into carboxylic acids, which are also formally called aldonic acid.
Because maltose and lactose have 1,4-glycosidic bonds (regardless of their alpha or beta conformations), this means that there is still at least one anomeric carbon capable of opening up into the open-chain aldehyde form (also known as mutarotation). Thus, it is called a reducing agent (reducing sugar).
And sucrose is not a reducing sugar because the anomeric carbons are both taken up in the alpha-1,2-glycosidic linkage, meaning that there's no chance for aldose formation....? Isn't beta-D-fructose a ketose though?
I did a bit of googling and I found that ketose sugars can tautomerize (rearranging bonds) resulting in an (enol), a double bond and -OH group. So ketoses also act as reducing sugars by becoming aldoses until a "keto-enol" shift under basic conditions...interesting.
aldoses = open chain carbohydrates with aldehyde as their oxidized functional group
ketoses = open chain carbon hydrates with ketone
hemiacetal = cyclic rings due to intramolecular reactions between an nucleophilic hydoxl group and electrophilic carbonyl carbon in an aldose
In fructose, hydroxyl group in C3 is in the opposite direction as others, as a result, OH resides inside the pentagon ring in C3. But when it becomes Sucrose, i noticed that hydroxyl group is inside of pentagon in C4. Can you please explain why?
Since it's a beta anomer, the OH on C-2 has to face the same side of ring as the CH2OH on C-5. The OH on C-4 also has to face the opposite side of ring as the OH on C-3. That leaves only one option, C3-OH facing down and C4-OH facing up.
A simpler way to think about it is to draw the furanose from the Fischer as you normally would, then flip it left to right (place the paper upside down). All top substituents go to the bottom and vice-versa.
these videos are so clear and helpful, thankyou so much
Thank you very much. I search for hours for a nice german statement. But its so much easy, when u explain it.
I have understood so much thank you
The reason the maltose C1 anomeric carbon is designated alpha is that it's former hydroxyl group, which is now the glycosidic O bond linking the two monsaccharides, is cis to (on the same side of the ring) as the 4th carbon's hydoxyl group. The lecturer was wrong when he referenced it to the position of the CH2OH group attached to carbon no. 5. That group is trans to the glycosidic O bond. The alpha/beta designations refer to the positions of the anomeric hydroxyl group and the hydroxyl group oxygen which is directly bound to the highest numbered chiral carbon in the ring.
My MCAT book defines it the same way he does, as the relationship with respect to the CH2OH (the 5th carbon). If it’s trans or pointing down, it’s alpha and if it’s cis or pointing up with respect to the 5th carbon then it’s beta-anomeric
Your lectures are so much informative and fantastic even for teachers
I'm in love w your handwriting 😍😍❤️
You are so organised
thank you so much,, for explaining.. I had a great experience Watching 😊
Lactose has both galactose and glucose in beta anomeric conformation not in alpha glucose
uh im not sure but i think that the glucose can be in the alpha or the beta confirmation to form Lactose with beta galactose
yeah, you are right. it is suppose to be linkage between beta galactose with beta glucose
It can be either, alpha or beta. Both join with beta-D-galactose to form lactose.
Both are correct .
@@brittopereppadan5503 Please explain how can a single natural disaccharide [Lactose] can have two different monomer units [alpha & beta Glucose] ..and still be called Lactose
Thanks
Thank you!!! Finally, I understand this.
U can't imagine how greatful I am thank u sir
amazing..... didn't need to read the Uni content at all after watching this !
I found this verrry helpfull as a med student thanks
Wouldn't for sucrose, you would need to specific alpha-1,-beta-2-glycosidic bond, since it's using both anomeric carbons?
You explain very well, 🙂🙂
Your explanation is simply tremendous 👍
Thank you!!! Finally I understand this.
Your strong pronunciation is great really learning here
Well a great video lecture.....it really built up my concepts
Much clearer than before ..thanks
Peter Anning yuequ
Yuequ
Hạch chen
مرتضى من العراق طالب طب مرحلة أولى شكرا لك
Thank you very much!!
very well put together lecture.
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Thank u... Love from Bangladesh
isn't lactose between beta galactose and BETA glucose?
Yes, it is. The -OH functional group in the C1 anomeric carbon of the glucose should be in the SAME DIRECTION as the CH2OH group (C6 carbon).
But take into account that because of mutarrotation, the glucose could potentially be Beta or Alpha (but its usually beta)
Hello sir. Is it supposedly a-D-fructose + a-D-glucose to create a-1,2-glucosidic bond?
thank you Andy
youre welcome!
Really helpful! Thank you!
To determine whether the glycosidic linkage is alpha or beta between two monosaccharides ( the first one for Beta and the second one for Alpha) , are we just looking at the first monosaccharide which is beta? (referring to lactose) :) Thanks!
+Tan Si Jie Yes, exactly.
Well explained ☺
But isn’t lactose~ beta-d-galactose + beta-d-glucose?
6. If a disaccharide is formed through a (1-> β4) glycosidic bond, it means that ________.
A. neither the first nor the second monosaccharide unit needs to be in the β-form
B. both monosaccharide units need to be in the β-form
C. only the first monosaccharide unit needs to be in the β-form
D. None of the above is correct.
Can someone help me with this qn?? )):
A
C
U are genius 😎
thank you!
Thanks sir ☺️
From india
Thanks alot
thank you... :D in english its so much easier than in german
bravo
Thanks sir
and maltose has alpha and beta glucose
monosacharides.
maltose contains free aldhyde group . that is , maltose is reducing sugar and the reducing sugar can be present in in alpha or beta form ...
just got it now... thank you
Thhhhankkkk you very so alot much 😁
What is the full name of lactose?،🧐🤔
good
That board scares the hell out of me and get me lost why not try with less written stuff up on there
Lactose=alpha galactose +beta glucose ???
No
Alpha glucose or beta glucose+ beta galactose
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I am, they are on my website.
α-glucose + α-fructose = sucrose
thank you so much !