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le (1h12m56s)
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Conférences
le (50m0s)
Quelles maths faut-il apprendre pour répondre aux questions des élèves et traiter leurs erreurs ?
... profession doit donc disposer d’au moins un des chemins de l’étude d’une œuvre incontournable dans toute formation scientifique : l’écriture symbolique mathématique, et ses usages en sciences, pour analyser la position des élèves sur ce chemin et les conduire... Voir la vidéo
Conférences
le (2h28m35s)
La recherche scientifique : confiance et vérité (par Bernard Michaux)
... les formes du jugement on distingue le juger vrai et le tenir pour vrai. Il faut pourtant remettre en question cette distinction et analyser par quelles procédures, par quelles normes, quelles règles de savoir-faire et de faire-savoir, la confiance... Voir la vidéo
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le (4m53s)
1.2. At the heart of the cell: the DNA macromolecule
During the last session, we saw how at the heart of the cell there's DNA in the nucleus, sometimes of cells, or directly in the cytoplasm of the bacteria. The DNA is what we call a macromolecule, that is a very long molecule. It's Avery, in 1944, who discovered that the DNA was the support of genetic information. But the scientists who are most well-known for DNA are Francis Crick and James Watson who discovered together, with Maurice Wilkins and Rosalind Franklin, in 1953, the structure of DNA, the famous double helix, the two strands. Here are Crick and Watson explaining on a very crude wire model far away ... Voir la vidéo
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le (7m22s)
1.3. DNA codes for genetic information
Remember at the heart of any cell,there is this very long molecule which is called a macromolecule for this reason, which is the DNA molecule. Now we will see that DNA molecules support what is called the "genetic information". So, DNAcodes for genetic information. How? If you consider this doublestrand molecule, DNA molecule, you remember that on each strandof the molecule, there is a succession of nucleotides. You can follow these nucleotides and write their name or moreexactly the initial of their name. And you will get what we call the sequence". Look: C, T, A and so on. The process by which you obtain this sequence of characters of ... Voir la vidéo
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le (5m49s)
1.4. What is an algorithm?
We have seen that a genomic textcan be indeed a very long sequence of characters. And to interpret this sequence of characters, we will need to use computers. Using computers means writing program. Writing program means designing first algorithm. So, let's see what an algorithm is. An algorithm is a series of operationsto be executed by a computer, but maybe also executed by ahuman, for solving a problem. In the first algorithm we will study in this session and next one, the problem will be to count the number of different of the four different nucleotides which appeared in the sequence. It's a sequence of operations. You may say that in ... Voir la vidéo
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le (5m11s)
1.5. Counting nucleotides
In this session, don't panic. We will design our first algorithm. This algorithm is forcounting nucleotides. The idea here is that as an input,you have a sequence of nucleotides, of bases, of letters, of characters which ends with a star symbol, here. And, you want to count the number of A,C, G and T, and then the frequencies. To write an algorithm in thispseudo code language, you need first to declare on which objector variables you will work. Here, we declare severalinteger variables. What does it mean integer variables? That is a variable, the value of which can be an integer: 1, 2, 3, minus 9 and so on. So, integer ... Voir la vidéo
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le (4m29s)
1.6. GC and AT contents of DNA sequence
We have designed our first algorithmfor counting nucleotides. Remember, what we have writtenin pseudo code is first declaration of variables. We have several integer variables that are variables which cantake as a value an integer. One, two, three minus five and so on. We have the sequence of characters we want to interpret, declare as a character string oflengths and define. Then we have the initializationof our different variables. This symbol is a symbol for assignment, it means that zero becomes the value of total nb, nbT and soon and so on and here we say: index takes the value one. It means that we position at the beginning of ... Voir la vidéo
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le (6m7s)
1.7. DNA walk
We will now design a more graphical algorithm which is called "the DNA walk". We shall see what does it mean "DNA walk". Walk on to DNA. Something like that, yes. But first, just have a look again at the typical, also quite short sequence of DNA, a long text offour letters: A, C, G, T, T and so on. When the first sequence of DNA were obtained, the idea of using computers very quickly emerged but people didn't know exactly what to do with this sequence of characters. Again, there is a meaning behind the sequence because it is genetic information. It means it is the information ... Voir la vidéo
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le (6m25s)
