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    (Original post by thegodofgod)
    Advanced Biology by Jones and Jones is excellent!

    Didn't realise it was that expensive though!
    Cheers mate!

    Haha, the price is fine. It'll be worth it at the end :teehee:
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    (Original post by aceySnicks_x)
    can someone help me with my thread, so far i have 149 views but no reply ):
    Which thread? :erm:
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    Hello!
    I would love to join our society. I'm interesting and fascinating about biology and other natural sciences! So Introduce myself!

    Name: Gregorius alias Kallisto
    Hobbies: reading, art, martial art, sport (mainly martial art ), natural science (physics, biology and chemistry of course)
    Where you live: Anywhere in Germany
    Current Studying level: Studying for my life and an A-level at the moment!
    What you are studying: natural sciences (physics, biology and chemistry), languages (German, English and Latin) and social sciences (history and politic/economy) - these are my subjects.
    Hero(s): Gregor Mendel is one of my hero in biology: he has discovered the mendelian inheritance which were an important step in genetics in my opinion!
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    I'm wonder why there is no a member who is writing in this topic. Okay, it's my turn again!
    I'm reading doctrines about molecular genetics. I want to know what happen by a glycosidic bond. Why is it so important for DNA? Please answer in a short comment, if it's possible.
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    (Original post by Kallisto)
    I'm wonder why there is no a member who is writing in this topic. Okay, it's my turn again!
    I'm reading doctrines about molecular genetics. I want to know what happen by a glycosidic bond. Why is it so important for DNA? Please answer in a short comment, if it's possible.
    Hi, a glycosidic bond is formed by a condensation reaction (one water molecule is lost), just like when two glucose molecules condense to form one molecule of maltose.

    The opposite of a condensation reaction is a hydrolysis reaction, which is where one molecule of water is added to a compound, which splits it into two, e.g. maltose + water --> 2 glucose.

    One nucleotide (the repeating unit of any nucleic acid, e.g. DNA, RNA) is joined up to another via a glycosidic bond. Also, each part of a nucleotide (the pentose sugar, the organic base, and the phosphate group) is linked by a glycosidic bond.
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    (Original post by thegodofgod)
    Hi, a glycosidic bond is formed by a condensation reaction (one water molecule is lost), just like when two glucose molecules condense to form one molecule of maltose. (...)
    Hmmm... that sounds after an esterification as in a reaction between deoxyribose and phosphoric acid in this case. One water molecule is lost as well by this reacton. That's why I think a glycosic bond is also an esterification. That makes sense, because a condensation reaction IS an one. Am I right?
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    (Original post by Kallisto)
    Hmmm... that sounds after an esterification as in a reaction between deoxyribose and phosphoric acid in this case. One water molecule is lost as well by this reacton. That's why I think a glycosic bond is also an esterification. That makes sense, because a condensation reaction IS an one. Am I right?
    Esterification is different as it has the following group:

    O
    ||
    C-O-R
    |
    R

    , whereas a glycosidic bond has the following group:

    ....R.....R
    ....|......|
    R-C-O-C-R
    ....|......|
    ....R.....R
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    Hello fellow Student Room Users
    I really need some help with a question im really puzzled with
    The question is
    Our Genetic information is stored in nitrogenous bases in our DNA, using examples explain how these nitrogenous bases code for amino acids and how the sequence of amino acids code for a poly peptides

    I would be very grateful if someone can help me answer this question.
    Thank you all
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    (Original post by A-d-S10)
    x
    So I have got informations in terms of nitrogenous bases. there are two of them.
    In the one hand there is purine which has adenine (A) and guanine (G) as bases. In the other hand ther is pyrimidine which has cytosine (C) and thymine (T) as bases. An amino acid consists of three bases, as in lysine which has adenine three times. That's why it must be purine in my consideration. "sequence of" means a chain of protein which consist of amino acids. One example is:
    lysine (AAA) - proline (CCC) - glycine (GGG) - and so on... in this case we have purine, pyrimidine and purine in that order. I hope I was able to help you.
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    (Original post by Kallisto)
    So I have got informations in terms of nitrogenous bases. there are two of them.
    In the one hand there is purine which has adenine (A) and guanine (G) as bases. In the other hand ther is pyrimidine which has cytosine (C) and thymine (T) as bases. An amino acid consists of three bases, as in lysine which has adenine three times. That's why it must be purine in my consideration. "sequence of" means a chain of protein which consist of amino acids. One example is:
    lysine (AAA) - proline (CCC) - glycine (GGG) - and so on... in this case we have purine, pyrimidine and purine in that order. I hope I was able to help you.
    Thank you very much for your help
    I do however need help with a Codon Question i really need help with
    It involves a codon wheel
    Can you help me please ?
    I can Pm you the worksheet
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    (Original post by A-d-S10)
    Thank you very much for your help
    I do however need help with a Codon Question i really need help with
    It involves a codon wheel
    Can you help me please ?
    I can Pm you the worksheet
    Of course, I can help you. What is the exactly problem? Have you difficulties in determination of amino acid? What do you have to do? give me an answer, please!

    By the way I hope my last answer was right in this way. I'm not sure, but it made sense in my point of view.
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    (Original post by Kallisto)
    Of course, I can help you. What is the exactly problem? Have you difficulties in determination of amino acid? What do you have to do? give me an answer, please!

    By the way I hope my last answer was right in this way. I'm not sure, but it made sense in my point of view.
    Iv sent you a PM Kallisto
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    Hello there. I've just recently joined the group, and I have a few questions.

    I'm finishing by GCSE's, and I've chosen to do Biology for A-Level next year. My Biology Teacher has given me a letter about a 2 day residential field trip for the 25th and 26th of June. It is supposed to be ideal preperation for the first exam in A2 Biology and the ISA exam, as well as a good thing to mention when applying for a Uni.

    I was a bit overwhelmed that the A-Level Biology trip is so soon, I mean my last GCSE Exam (Geography) is on the date that we actually leave to go on this A-Level trip! I was wondering whether you guys have done something like this, or if you are doing something like this, and whether you can tell me anything else about it and what should we do if anything to prepare for it.
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    (Original post by Dobrzynski)
    Hello there. I've just recently joined the group, and I have a few questions.

    I'm finishing by GCSE's, and I've chosen to do Biology for A-Level next year. My Biology Teacher has given me a letter about a 2 day residential field trip for the 25th and 26th of June. It is supposed to be ideal preperation for the first exam in A2 Biology and the ISA exam, as well as a good thing to mention when applying for a Uni.

    I was a bit overwhelmed that the A-Level Biology trip is so soon, I mean my last GCSE Exam (Geography) is on the date that we actually leave to go on this A-Level trip! I was wondering whether you guys have done something like this, or if you are doing something like this, and whether you can tell me anything else about it and what should we do if anything to prepare for it.
    If the college you go to is anything like mine then you'll have the option to go after your AS levels and before A2 starts. Ours was about late June/early July last year, after our AS exams. Personally I wouldn't know if the trip helps. I never went and I got an A in the January exam this year.
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    (Original post by NessEB)
    If the college you go to is anything like mine then you'll have the option to go after your AS levels and before A2 starts. Ours was about late June/early July last year, after our AS exams. Personally I wouldn't know if the trip helps. I never went and I got an A in the January exam this year.
    Thanks for the reply. I've figured it would be a good experience nonetheless though.
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    Hi, I´d like to ask: Is Hamilton´s rule specifically used only for when one individial helps/saves exactly one individual (rB > C)? I got across the example when one brother saves the other one from drowning. The rule was applied like this: B=2 (average number of offspring for humans), r=0.5 (since they are brothers) and C = 0.25 (probability the brother will drown if the other will not save him) times 2 (the number of expected offspring if the altruist had stayed on the shore). Thus, it is beneficial for one brother to save the other. But, what would happen if two of his brothers were drowning (and he could save both)? I realize that if it is beneficial to save one, then it follows that it is advantageous to save both (if trying to save the second, does not endager them all - again, assume both can be saved), but how would the rule be applied? How would it be like mathematically?

    When it comes to the cost of "the provider", you can figure out the average probability they both will die, but how would “the-benefit-to-the-recipients” side of the inequality look like? Because, I don´t think you can just sum it up (r1B1 +r2B2; B1=B2) (or, to say it differently, multiply the benefit of one brother by two) as 50% of genes they share with the altruist is (if only in the minor part) different set of 50% (yes, r1 and r2 are both 0.5 mathematically, but when comparing "the biological character" = gene content of what r1/r2 respresent, then they are not the same). Thus – if we think of drowning brothers in the terms of genes, the altruist will – in total – save more than 50%…be it even 50.00000001%…

    We don´t even have to consider this ("drowning") example - I am simply interested in the maths of Hamilton rule when "the altruistic act" of an individual saves more than one individual (for this purpose, all of them can be siblings of the altruist).

    So? I am curious to know how this works...
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    (Original post by Dominika4)
    Hi, I´d like to ask: Is Hamilton´s rule specifically used only for when one individial helps/saves exactly one individual (rB > C)? I got across the example when one brother saves the other one from drowning. The rule was applied like this: B=2 (average number of offspring for humans), r=0.5 (since they are brothers) and C = 0.25 (probability the brother will drown if the other will not save him) times 2 (the number of expected offspring if the altruist had stayed on the shore). Thus, it is beneficial for one brother to save the other. But, what would happen if two of his brothers were drowning (and he could save both)? I realize that if it is beneficial to save one, then it follows that it is advantageous to save both (if trying to save the second, does not endager them all - again, assume both can be saved), but how would the rule be applied? How would it be like mathematically?

    When it comes to the cost of "the provider", you can figure out the average probability they both will die, but how would “the-benefit-to-the-recipients” side of the inequality look like? Because, I don´t think you can just sum it up (r1B1 +r2B2; B1=B2) (or, to say it differently, multiply the benefit of one brother by two) as 50% of genes they share with the altruist is (if only in the minor part) different set of 50% (yes, r1 and r2 are both 0.5 mathematically, but when comparing "the biological character" = gene content of what r1/r2 respresent, then they are not the same). Thus – if we think of drowning brothers in the terms of genes, the altruist will – in total – save more than 50%…be it even 50.00000001%…

    We don´t even have to consider this ("drowning") example - I am simply interested in the maths of Hamilton rule when "the altruistic act" of an individual saves more than one individual (for this purpose, all of them can be siblings of the altruist).

    So? I am curious to know how this works...
    Hmm… Since no one else has replied, I think I'll take a shot. As you have implied, the entire thing revolves around the inequality of br>c. 'b' is the benefit gained to the system of genes, r is the relatedness and c is the potential cost of the person who is doing the altruistic act.
    First things first, I think for this question, it is better to talk about a ‘system’, consisting of the potential altruist’s genes. Hence, all benefits and costs are given relative to what they add or take away from the system.
    I tend to think of the inequality as a comparison between two sets of events - i.e. success and failure. Let us consider your first scenario for starters – is it feasible for a brother to jump of his boat (I assume he is on a boat) to save his brother?
    Assuming that the altruistic brother jumps in and attempts a rescue, there are three discrete sets of events – (1) The act is successful, both brothers live. (2) The altruistic brother jumps in and attempts a rescue, but cannot stop his brother from drowning. He himself, however, is able to survive. (3) The rescue attempt is a disaster – both brothers drown. Outcome (1) is a benefit to the system, but outcome (3) is a cost to the system.
    Outcome (2) yields no change to the system. So we do NOT need to consider event (2) in our equation. This is because if event (2) does happen, then there is no change to the genetic material in the system – i.e. the altruistic brother was alive before the event and alive after the event, and the genes of the now drowned brother has not been added to the system. Thus, whatever probability of this event is, it will be multiplied by zero, as no change to the system has happened.

    Let us now consider the inequality - the LHS of the inequality signifies the the potential amount of related genetic material the system gains if the altruistic act is performed, weighted against the probability that the altruistic act is successful (i.e. the brother is saved) .
    The potential amount of related genetic material gained by the system is equal to
    the relatedness ‘r’ of the brother (0.5) X Number of offspring that will be likely produced by the brother ‘b’ if he is saved from drowning (2) X Probability that the drowning brother is successfully saved (let’s call this probability ‘m’).

    Thus, the LHS becomes 0.5 x 2 x m, which is numerically equal to just ‘m’.

    The RHS, however, represents the cost of failure, weighted against the probability of failure, which here would be
    2 (because the system would loose two offspring that the altruistic brother would have produced if he had children) multiplied by the probability of failure (i.e. the brothers drown) (let’s call this n).

    Thus, the RHS becomes 2 x n.

    Thus, via substitution, the inequality br > c reduces to
    ‘The altruistic act is only feasible, in this scenario, if m > 2n.’ i.e. the probability of saving the drowning brother must at least be twice as great as the probability that they will both drown, to make the altruistic act genetically feasible.

    ok, that’s the easy part done.

    Now, for the second part – your question focusing on how to 'sum' relatedness when more than one person is drowning, is a little more tricky, and I think my line of thinking may be wrong, but here it is anyway.

    Say two brothers are drowning, and let us assume that saving the two brothers is twice as risky as saving one brother from drowning (a fair assumption I think). There are, this time, five discrete events assuming that the brother on the boat jumps in and attempts to save them. (1) Both drowning brothers are saved. (2) One drowning brother is saved, the other drowning brother is unable to be saved, but the altruistic brother manages to survive the second rescue attempt. (3) One drowning brother is saved, but as the altruistic brother attempts a heroic rescue to save the second drowning brother, he is unsuccessful, and they both perish (4) No drowning brothers are saved, but the altruistic brother who jumped in is manages to SURVIVE. (5) No drowning brothers are saved, but the altruistic brother who jumped in DIES.

    Events (1) and (2) are potential benefits to the system.

    Event (3) is a bit strange, in that one drowning brother is saved, but at the cost of the altruistic brother. Hence, the saving of one drowning brother is a benefit, but there is also the cost of the original altruistic brother.

    Event (4) is neutral to the system.

    Event (5) is a cost to the system.

    This time, we need not consider event (4) for the same reasons as we did not need to consider event (2) in the previous scenario.
    So what about the LHS then? This time, since we are considering multiple people to be saved, the LHS should be the sum of the ‘br’ for each of the separate events. Hence, the LHS can be summed up as –
    P(Event 1) x ‘b’ of event 1 x ‘total relatedness of brothers saved relative to the altruistic brother’ +
    P(Event 2) x ‘b’ of event 2 x ‘total relatedness of brothers saved relative to the altruistic brother’ +
    P(event 3) x ‘b’ of saving the single brother x ‘total relatedness of brother saved relative to the altruistic brother’.

    So this is in essence, what our LHS should consist of. Let us first consider the probability of each of the three events. Event 1 involves the altruistic brother jumping in once to save one drowning bother and then again to save the other one. Remember that I used ‘m’ in the previous scenario to represent probability that the altruistic bother manages to save the only drowning brother and both of them survive. In this case, we want to probability that this will happen twice in succession, which will be m^2.
    By similar reasoning, we can say P(Event 2) = m. P(Event 3) = m x n. (if this is unclear, feel free to quote me and ask me why, but it is right I think).
    Our ‘b’ for each event is the number of brothers saved multiplied by 2 (2 is the number of offspring they each will produce)

    Okay, that was the easy bit.

    The hard bit, and the one related to your question, is ‘how do we find the relatedness that we need for Event 1 which has two brothers?’ This is an educated guess, but I think we need to consider the two brothers AS A SINGLE SYSTEM OF GENES, whose relation to the altruists genes is compared by our 'r' in the inequality. I think the relatedness of the system consisting of the two drowning brothers is given by the reciprocal of the sum of their reciprocals of their relatedness. i.e. 1/r = (1/r of brother 1) + (1/r of brother 2). Thus, 1/r = (1/0.5) + (1/0.5) = 4. Thus, our ‘r’ in the equality is 1/4, or, 0.25.
    Thus, the LHS equation becomes –
    [(m^2) x 2 x 2 x 0.25] + [m x 2 x 0.5] + [(mn) x 2 x 0.5], this is equal to m^2 + m + mn

    Phew, now for the RHS – the cost of Events 3 and 5 (remember, we don’t consider 4). Since we have more than one possible event, we need to sum up the individual ‘potential costs weighted with their respective probability’.

    This is equal to
    P(Event 3) x cost to the system of losing the original altruistic brother +
    P(Event 5) x cost to the system of losing the original altruistic brother.
    P (event 3) = mn and P(Event 5) = n (again, if unclear why, feel free to PM/quote me)

    The cost is 1, since it is the altruistic brother that perishes.

    Thus, the RHS equals
    [(mn) x 1] + [(n) x 1], which is just mn+n.
    Now that we have both the RHS and the LHS, we can say ‘It is only genetically feasible for the brother on the boat to jump down and save his two siblings if, and only if,
    m^2 + m + mn > mn + n (or more simply m^2 + m – n > 0 ).’

    Thanks god that’s over. Sorry for the big read. If that does not make sense (trust me, I wrote it and I get lost reading it), feel free to quote/PM me, I’ll do my best to clarify. To answer your original question is a couple of words – when dealing with multiple people that need to be saved, consider them as a single system, with their relatedness equal to reciprocal of the sum of their reciprocals. I don’t know what year you are in, but if you have done physics, you may realise this is the same method for adding resistors in parallel. If you are really math savvy, you may also realise the hints of Pascal’s triangle with respect to the number of events possible as the number of bothers increases. I also suspect that the Binomial Distribution has something to do with it, but they scare the hell outta me, so I'll leave it at that.
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    Does anyone know of any good resources for enzyme kinetics? (I'm a biotech first year, but the basics would be good!) thanks
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    I just couldn't resist posting this here. You guys give pretty good responses!

    Please help with this one:
    Descibe an experiment to show the response of a named invertebrate animal to a named stimulus.
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    (Original post by xXFrenchKicksXx)
    Does anyone know of any good resources for enzyme kinetics? (I'm a biotech first year, but the basics would be good!) thanks
    There's a biochemistry book ,
    Check this out on AMZN: Biochemistry: International Edition http://amazon.co.uk/dp/071676766X


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