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The Biology AS-level Thread

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Reply 680
Bunch of query’s or queries that need solving!
1) Carbohydrates such as starch and maltose and all that sort of stuff are made up of monosaccharide’s joined together via glysodic bond that have been formed by a condensation reaction i.e. the removal of water. Right…so how is the removal of water brought about? Is this by the energy of ATP splitting into ADP +pI? Which provides the energy for the removal of water and hence forming the glysodic bond? In addition to this when you hydrolyse the glysodic bond i.e. adding water…is it fair to say this is where the pI and ADP reform.
Staying on the topic of bonds is it also true to say peptide bonds between amino acids are formed in the same way? i.e. ATP splitting which provides energy to remove water and when the bond (peptide) is broken reforms ATP?
Original post by king101
Bunch of query’s or queries that need solving!
1)Carbohydrates such as starch and maltose and all that sort of stuff are made up of monosaccharide’s joined together via glysodic bond that have been formed by a condensation reaction i.e. the removal of water. Right…so how is the removal of water brought about? Is this by the energy of ATP splitting into ADP +pI? Which provides the energy for the removal of water and hence forming the glysodic bond? In addition to this when you hydrolyse the glysodic bond i.e. adding water…is it fair to say this is where the pI and ADP reform.
Staying on the topic of bonds is it also true to say peptide bonds between amino acids are formed in the same way? i.e. ATP splitting which provides energy to remove water and when the bond (peptide) is broken reforms ATP?


Enzymes. Always enzymes. That's not to say ATP isn't involved, but it seems unlikely to me. That would require cells to pump ATP into the digestive tubes and whatnot (seems a very expensive strategy). I'd guess enzymes reduce the activation of both hydrolysis and condensation reactions to the point where they'll occur without energy input other than the kinetic energy of the substrates.


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Reply 682
Original post by William Turtle
Enzymes. Always enzymes. That's not to say ATP isn't involved, but it seems unlikely to me. That would require cells to pump ATP into the digestive tubes and whatnot (seems a very expensive strategy). I'd guess enzymes reduce the activation of both hydrolysis and condensation reactions to the point where they'll occur without energy input other than the kinetic energy of the substrates.


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Oh glad you told me that or else I would be writting fluff in my essay. Could you shed some light on this essay then?

The different ways in which organisms use ATP:
(Since I kept thinking ATP was for protein synthesis and DNA synthesis and Carbohydrate synthesis I cant use all that stuff!)
But here is a few I have:
Muscle contraction..
ATP-ADP + pI
Maintaining resting potential
Plants uptake of water/nitrates
Absorption of Glucose

can you think of anymore?
Reply 683
Onto a slightly different point about species.

Members of the same species i.e. human posses the same genes but just different forms of them right?

But is it true to say different species posses different genes and hence code for different proteins which therefore give them different features.
Original post by king101
Oh glad you told me that or else I would be writting fluff in my essay. Could you shed some light on this essay then?

The different ways in which organisms use ATP:
(Since I kept thinking ATP was for protein synthesis and DNA synthesis and Carbohydrate synthesis I cant use all that stuff!)
But here is a few I have:
Muscle contraction..
ATP-ADP + pI
Maintaining resting potential
Plants uptake of water/nitrates
Absorption of Glucose

can you think of anymore?


I assume you're doing A2 bio, since you have essays.
ATP IS used for protein synthesis.

The main areas I can think of at this moment are the following:
1. Active transport - I'd break this down into sodium-potassium pump (in neurons and in creating a Na+ gradient for glucose co-transport) in animals and the absorption of minerals in plants.
2. Muscle contraction - ATP attaching to tropomyosin
3. Worthwhile doing a section on the production of ATP - oxidative phosphorylation in mitochondria, phosphorylation by phosphocreatine in muscles, substrate-level phosphorylation in glycolysis, pretty sure some is produced in photosynthesis (and used in photosynthesis).
4. Also a section on why ATP is suitable - fairly unstable (so release energy easily - makes it a good short-term energy store), small 'packets' of energy.
5. Phosphorylation of glucose in glycolysis to make it more reactive.
6. ATP used in protein synthesis.

I'm sure there are lots more (I can't remember much about photosynthesis), but there's probably enough for a bio essay.
Original post by king101
Onto a slightly different point about species.

Members of the same species i.e. human posses the same genes but just different forms of them right?

But is it true to say different species posses different genes and hence code for different proteins which therefore give them different features.


That is indeed correct (basically, at least). Different genotypes => different proteins produced => different phenotypes
Reply 686
Original post by William Turtle
I assume you're doing A2 bio, since you have essays.
ATP IS used for protein synthesis.

The main areas I can think of at this moment are the following:
1. Active transport - I'd break this down into sodium-potassium pump (in neurons and in creating a Na+ gradient for glucose co-transport) in animals and the absorption of minerals in plants.
2. Muscle contraction - ATP attaching to tropomyosin
3. Worthwhile doing a section on the production of ATP - oxidative phosphorylation in mitochondria, phosphorylation by phosphocreatine in muscles, substrate-level phosphorylation in glycolysis, pretty sure some is produced in photosynthesis (and used in photosynthesis).
4. Also a section on why ATP is suitable - fairly unstable (so release energy easily - makes it a good short-term energy store), small 'packets' of energy.
5. Phosphorylation of glucose in glycolysis to make it more reactive.
6. ATP used in protein synthesis.

I'm sure there are lots more (I can't remember much about photosynthesis), but there's probably enough for a bio essay.



Thanks for that! :smile:

So when you say ATP is needed for protein synthesis if that to provide the energy for the condensation reaction to form the peptide bonds between the amino acids. Also could atp be used for monosacharides being joined together i.e. the glysodic bonds?
Reply 687
Original post by William Turtle
That is indeed correct (basically, at least). Different genotypes => different proteins produced => different phenotypes


Great Thanks! :smile:
Original post by king101
Thanks for that! :smile:

So when you say ATP is needed for protein synthesis if that to provide the energy for the condensation reaction to form the peptide bonds between the amino acids. Also could atp be used for monosacharides being joined together i.e. the glysodic bonds?


It does so indirectly. I believe the energy causes the ribosome to change shape which allows the condensation reaction.
Reply 689
Original post by William Turtle
It does so indirectly. I believe the energy causes the ribosome to change shape which allows the condensation reaction.


Ah right so in my essay it would be alright to say somthing like ATP also has a vast uses in the synthesis of polymers/macromolecules such as proteins and carbohydrates. One example is in the formation of polypeptides that form the proteins connected amino acids by peptide bonds formed via a condensation reaction removing water involving an enzyme and the energy carrying molecule ATP. ATP splits to form ADP +pI releasing energy for the condensation reaction to occur and hence forming the peptide bonds between the amino acids and hence forming the protein. In addition to this monosachardies...
Original post by William Turtle
I assume you're doing A2 bio, since you have essays.
ATP IS used for protein synthesis.

The main areas I can think of at this moment are the following:
1. Active transport - I'd break this down into sodium-potassium pump (in neurons and in creating a Na+ gradient for glucose co-transport) in animals and the absorption of minerals in plants.
2. Muscle contraction - ATP attaching to tropomyosin
3. Worthwhile doing a section on the production of ATP - oxidative phosphorylation in mitochondria, phosphorylation by phosphocreatine in muscles, substrate-level phosphorylation in glycolysis, pretty sure some is produced in photosynthesis (and used in photosynthesis).
4. Also a section on why ATP is suitable - fairly unstable (so release energy easily - makes it a good short-term energy store), small 'packets' of energy.
5. Phosphorylation of glucose in glycolysis to make it more reactive.
6. ATP used in protein synthesis.

I'm sure there are lots more (I can't remember much about photosynthesis), but there's probably enough for a bio essay.


Lots of great information here, but a few nitpicks to add in:

Pretty much any form of ion transport that relies on a sodium gradient being present parasitises the sodium-potassium pump, It really is everywhere!

ATP attaches to the actinomyosin complex (more common terminology is just myosin head, or myosin ATPase), as opposed to tropomyosin (this is what calcium binds to via troponin to let muscular contraction happen!)
(edited 10 years ago)
Reply 691
Just a quick question, In Meiosis....I was getting slightly confused, during anaphase one one of the double chromosomes is pulled to each end and then anaphase II the chromosome is pulled to 2 chromatids? is a chromatid a chromosome and if yes then surely in part A of meiosis there are 92 chromosomes present.



Also, random segregation & independent segregation....are they the same thing?
(edited 10 years ago)
I got an A in AS Biology but after just nine months it seems so rusty and slow to recall. Why is Biology like this?

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Original post by AhmedDavid
Just a quick question, In Meiosis....I was getting slightly confused, during anaphase one one of the double chromosomes is pulled to each end and then anaphase II the chromosome is pulled to 2 chromatids? is a chromatid a chromosome and if yes then surely in part A of meiosis there are 92 chromosomes present.


This is just a matter of terminology. A chromatid is one-half of a duplicated chromosome. When you pull them apart (so that there's no longer any joining at a centromere), we call them chromosomes again. Then when that chromosome replicates, we've got a duplicated chromosome made up of 2 chromatids again. Chromatids are genetically identical to chromosomes, but the differences come in with the structures around the centromere.

You're right that a cell before division (whether this be mitosis or meoisis 1) has 92 "sets" of genetic information. But there are still only 46 chromosomes present because of our difference between duplicated chromosomes, unduplicated chromosomes, and chromatids.


Also, random segregation & independent segregation....are they the same thing?


Same thing. :smile:


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Original post by Hype en Ecosse
Lots of great information here, but a few nitpicks to add in:

Pretty much any form of ion transport that relies on a sodium gradient being present parasitises the sodium-potassium pump, It really is everywhere!

ATP attaches to the actinomyosin complex (more common terminology is just myosin head, or myosin ATPase), as opposed to tropomyosin (this is what calcium binds to via troponin to let muscular contraction happen!)


Glucose is the specific example in AQA AS bio.

Ahh yes, I did know that. Just so many names..
Original post by king101
Ah right so in my essay it would be alright to say somthing like ATP also has a vast uses in the synthesis of polymers/macromolecules such as proteins and carbohydrates. One example is in the formation of polypeptides that form the proteins connected amino acids by peptide bonds formed via a condensation reaction removing water involving an enzyme and the energy carrying molecule ATP. ATP splits to form ADP +pI releasing energy for the condensation reaction to occur and hence forming the peptide bonds between the amino acids and hence forming the protein. In addition to this monosachardies...


I suppose that'd be fine (see what your teacher says). I'd switch 'ribosome' in for 'enzyme' in polypeptide synthesis.
Reply 696
Original post by William Turtle
I suppose that'd be fine (see what your teacher says). I'd switch 'ribosome' in for 'enzyme' in polypeptide synthesis.


Ah right cool. Yes in the text book it does mention about ATP and an enzyme being required for protein synthesis so I geuss It would be fine.

I'm an external candidate so have no teacher, that's why I have to rely on great minds of SR :smile:.

Just one last thing I just cannot seem to convince myself if it is correct terminology to say ATP is required for carbohydrate synthesis i.e. monosachardies joined together via glysodic bond. It's just in the text book it makes no reference to any ATP molecule being involved or does not even specifiy how the bond is formed apart from a condensation reaction.

Would you suggest for the carbohydrates syntehsis part I leave out ATP being used to synthesise it--since I may loose marks if it is not true.
Original post by king101
Ah right cool. Yes in the text book it does mention about ATP and an enzyme being required for protein synthesis so I geuss It would be fine.

I'm an external candidate so have no teacher, that's why I have to rely on great minds of SR :smile:.

Just one last thing I just cannot seem to convince myself if it is correct terminology to say ATP is required for carbohydrate synthesis i.e. monosachardies joined together via glysodic bond. It's just in the text book it makes no reference to any ATP molecule being involved or does not even specifiy how the bond is formed apart from a condensation reaction.

Would you suggest for the carbohydrates syntehsis part I leave out ATP being used to synthesise it--since I may loose marks if it is not true.


I've never heard anyone mention ATP being used in polysaccharide synthesis, so yes, I would leave it out if I were you.
Reply 698
Original post by William Turtle
I've never heard anyone mention ATP being used in polysaccharide synthesis, so yes, I would leave it out if I were you.


Righty thank you for saving me relevance marks! :biggrin:
In the AQA AS biology Nelson Thornes book on pg 144 the question 2Bi asks which part of the DNA molecule is a base, I thought it would be A ( organic base) but the answer is B (deoxyribose sugar), can someone please tell me why?

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