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From PN Campbell
183 In its presence iron(II) is rapidly oxidized by dissolved oxygen from the air, and that is why the E D T A and FeSO4 are mixed just before use.
Review of Results Notice that three processes occurred: (1) the protein separated from the (yellow) hexacyanoferrate (III), (2) it then passed through the iron(II) salt and was reduced by it, (3) the iron(II) form of the protein combined with 02. Because the solution of 02 was not concentrated (about 0.25 mM), the haemoglobin had to pass through an appreciable volume to complete oxygenation. Nevertheless the 8 cm of column length was enough for completion of all three processes. You were asked why the line between the two forms Hb and HbO2 gets progressively further from the band of iron(II) salt. The reason is that conversion of the haemoglobin into oxyhaemoglobin clears an appreciable volume of buffer of its dissolved oxygen.
Reference i Dixon, H B F and McIntosh, R (1967) Nature 213, 399-400
Letters to the Editor From P N Campbell
The History of Biochemistry My friend, Derek Evered, asks in his Editorial (Biochemical Education 13, 97, 1985) "What then is the purpose of teaching or studying the history of a scientific discipline apart from the scholarly aspect?". He mentions that his lectures about biochemical history were not well received by his students. My view is that a lecturer should impart an impression of historical depth not only for scholarly reasons but also because the students will appreciate being taken from the solid foundations of a subject to the cutting edge. I remember a famous occasion when the plenary lecturer at a Congress said that we were to forget the contents of the abstract he had circulated for everything he was going to tell us had been discovered in the last six months. My response was to want to leave the lecture hall and return in another six months and see whether the lecturer took the same stance. My reply therefore to the Editorial is that lectures on biochemical history are unlikely to be appreciated; but that historical perspective should be an essential ingredient of all lectures. P N Campbell
Courtauld Institute of Biochemistry The Middlesex Hospital Medical School Mortimer Street London W1P 7PN, UK From M Carroll
Microcomputer Programs Dear Sir, Dr M F Chaplin was rather harsh in his review of the biochemical micro-computer programs written by Dr David Bender. We have found the 'Enzyme Assay' program to be a useful teaching aid for first-year pre-clinicai medical students. Admittedly, we have exploited the "relatively unsophisticated style" in order to improve on the original. With the help of Dr Holman of our computer centre, we have prevented the program crashing from out-of-range inputs, replaced the flashing cursor by the message "Please wait while results are calculated", and introduced an algorithm that limtis the number of significant figures to 3, hence tidying up the tables of results.
BIOCHEMICAL EDUCATION 13(4) 1985
We have found Dr Bender's program to be of more value than the other micro-computer programs on enzymology currently available. It certainly covers more ground than could be achieved in a class practical. The students prefer it too. Yours faithfully M Carroll
Department of Biochemistry The London Hospital Medical College London E1 2AD
Microcomputer Software Review Genesim - - Elsevier Biosoft by P W o o d T e a c h e r s m a n u a l , 10 c o p i e s o f s t u d e n t s ' m a n u a l a n d f l o p p y disc for A p p l e II, I B M - P C o r B B C - B . $45 o r £30 This package consists of five sections, the first four of which are designed to present a computer simulation of experiments in bacterial genetics and restriction mapping and the last of which is designed to familiarise a student with the genetic code and simple classes of mutation. The review copy contained the BBC version of the software. The aim of the package is to use the computer to generate data which the student then uses for calculations and thus to overcome the need for actual experimental manipulations. The first program covers an interrupted mating, the second extends this to cover six Hfr donors so that a circular linkage map can be constructed; the third covers two-point and three-point analyses from a P1 transduction; the fourth section is an elementary restriction mapping exercise; the final section generates a short D N A sequence and requires the user to identify initiation and termination codons and predict the consequences of certain mutational changes. The computer is entirely 'unfriendly' and the package certainly assumes a fairly strict type of supervision. The user is enjoined to take graph paper, pen and calculator into the room. Moreover before attempting any section, a student is supposed to complete to his/her teacher's satisfaction some MCQs printed at the back of the student's notes. I must confess that I found the whole exercise extremely boring and, on occasions, infuriating. Given the limitations of the programs, I did not discover many scientific errors. However the 'correct' answer to MCQ No 1 on page 15 in the teacher's notes is totally misleading and the whole of this section (which deals largely with transduction) really only refers to Pl-mediated transduction although this is not specified in the text. The current length of the E coli chromosome is 100 min (not 90). An m R N A base change may (not will) result in an amino acid substitution; a chain-terminating codon is not (necessarily) outside the 'coding region' of mRNA. Other problems on the borderline between being scientific errors and inadequate programming include the inability of the computer to recognize G U G as an initiation codon, a consistent error in calculating standard errors in the transduction data arguably and most serious of all, the total refusal of the computer to accept certain abbreviations even though these are not only standard but are used in the accompanying literature. In particular, amino acid abbreviations have to be typed in upper case, so do the abbreviations for restriction enzymes and, for example, AraC has to be entered as ARA C. Another very confusing section actually invites the user to mutate a sequence to generate premature chain termination. The only way to proceed is to answer a question incorrectly by entering an amino acid abbreviation. The quality of programming is truly lamentable. On many occasions, the computer asks questions to which it does not know the answer - - presumably I should have consulted my teacher about these problems. Most infuriating of all, the computer simply refuses to use its own data-base: when asking for the order of genes or amino acid substitions, it cannot
Review of Results Notice that three processes occurred: (1) the protein separated from the (yellow) hexacyanoferrate (III), (2) it then passed through the iron(II) salt and was reduced by it, (3) the iron(II) form of the protein combined with 02. Because the solution of 02 was not concentrated (about 0.25 mM), the haemoglobin had to pass through an appreciable volume to complete oxygenation. Nevertheless the 8 cm of column length was enough for completion of all three processes. You were asked why the line between the two forms Hb and HbO2 gets progressively further from the band of iron(II) salt. The reason is that conversion of the haemoglobin into oxyhaemoglobin clears an appreciable volume of buffer of its dissolved oxygen.
Reference i Dixon, H B F and McIntosh, R (1967) Nature 213, 399-400
Letters to the Editor From P N Campbell
The History of Biochemistry My friend, Derek Evered, asks in his Editorial (Biochemical Education 13, 97, 1985) "What then is the purpose of teaching or studying the history of a scientific discipline apart from the scholarly aspect?". He mentions that his lectures about biochemical history were not well received by his students. My view is that a lecturer should impart an impression of historical depth not only for scholarly reasons but also because the students will appreciate being taken from the solid foundations of a subject to the cutting edge. I remember a famous occasion when the plenary lecturer at a Congress said that we were to forget the contents of the abstract he had circulated for everything he was going to tell us had been discovered in the last six months. My response was to want to leave the lecture hall and return in another six months and see whether the lecturer took the same stance. My reply therefore to the Editorial is that lectures on biochemical history are unlikely to be appreciated; but that historical perspective should be an essential ingredient of all lectures. P N Campbell
Courtauld Institute of Biochemistry The Middlesex Hospital Medical School Mortimer Street London W1P 7PN, UK From M Carroll
Microcomputer Programs Dear Sir, Dr M F Chaplin was rather harsh in his review of the biochemical micro-computer programs written by Dr David Bender. We have found the 'Enzyme Assay' program to be a useful teaching aid for first-year pre-clinicai medical students. Admittedly, we have exploited the "relatively unsophisticated style" in order to improve on the original. With the help of Dr Holman of our computer centre, we have prevented the program crashing from out-of-range inputs, replaced the flashing cursor by the message "Please wait while results are calculated", and introduced an algorithm that limtis the number of significant figures to 3, hence tidying up the tables of results.
BIOCHEMICAL EDUCATION 13(4) 1985
We have found Dr Bender's program to be of more value than the other micro-computer programs on enzymology currently available. It certainly covers more ground than could be achieved in a class practical. The students prefer it too. Yours faithfully M Carroll
Department of Biochemistry The London Hospital Medical College London E1 2AD
Microcomputer Software Review Genesim - - Elsevier Biosoft by P W o o d T e a c h e r s m a n u a l , 10 c o p i e s o f s t u d e n t s ' m a n u a l a n d f l o p p y disc for A p p l e II, I B M - P C o r B B C - B . $45 o r £30 This package consists of five sections, the first four of which are designed to present a computer simulation of experiments in bacterial genetics and restriction mapping and the last of which is designed to familiarise a student with the genetic code and simple classes of mutation. The review copy contained the BBC version of the software. The aim of the package is to use the computer to generate data which the student then uses for calculations and thus to overcome the need for actual experimental manipulations. The first program covers an interrupted mating, the second extends this to cover six Hfr donors so that a circular linkage map can be constructed; the third covers two-point and three-point analyses from a P1 transduction; the fourth section is an elementary restriction mapping exercise; the final section generates a short D N A sequence and requires the user to identify initiation and termination codons and predict the consequences of certain mutational changes. The computer is entirely 'unfriendly' and the package certainly assumes a fairly strict type of supervision. The user is enjoined to take graph paper, pen and calculator into the room. Moreover before attempting any section, a student is supposed to complete to his/her teacher's satisfaction some MCQs printed at the back of the student's notes. I must confess that I found the whole exercise extremely boring and, on occasions, infuriating. Given the limitations of the programs, I did not discover many scientific errors. However the 'correct' answer to MCQ No 1 on page 15 in the teacher's notes is totally misleading and the whole of this section (which deals largely with transduction) really only refers to Pl-mediated transduction although this is not specified in the text. The current length of the E coli chromosome is 100 min (not 90). An m R N A base change may (not will) result in an amino acid substitution; a chain-terminating codon is not (necessarily) outside the 'coding region' of mRNA. Other problems on the borderline between being scientific errors and inadequate programming include the inability of the computer to recognize G U G as an initiation codon, a consistent error in calculating standard errors in the transduction data arguably and most serious of all, the total refusal of the computer to accept certain abbreviations even though these are not only standard but are used in the accompanying literature. In particular, amino acid abbreviations have to be typed in upper case, so do the abbreviations for restriction enzymes and, for example, AraC has to be entered as ARA C. Another very confusing section actually invites the user to mutate a sequence to generate premature chain termination. The only way to proceed is to answer a question incorrectly by entering an amino acid abbreviation. The quality of programming is truly lamentable. On many occasions, the computer asks questions to which it does not know the answer - - presumably I should have consulted my teacher about these problems. Most infuriating of all, the computer simply refuses to use its own data-base: when asking for the order of genes or amino acid substitions, it cannot