Notice
2.3. The genetic code
- document 1 document 2 document 3
- niveau 1 niveau 2 niveau 3
Descriptif
Genes code for proteins. What is the correspondence betweenthe genes, DNA sequences, and the structure of proteins? The correspondence isthe genetic code. Proteins have indeedsequences of amino acids. There are 20 amino acidsin the living world. They can be named by a single letter,3 letters or their full name. It means that a protein can berepresented by a sequence of letters in a 20 letter alphabet. Let's come back again on thiscorrespondence between gene and protein. Genes are regions of DNA. These regions are first transcribedinto RNA and then RNA into proteins. And proteins’ sequences of aminoacids fold into 3D structures. Like here, some helixes. Translation is the process whichgoes from RNA to proteins. What is the code used bythis translation process? The code is the correspondencebetween DNA-RNA sequences, a four letter alphabet, to aminoacids sequences, protein, twenty letter alphabet. So let's think a littlebit about the structure of this code. It cannot be a one to onecorrespondence that is one nucleotide of DNA or RNA to one amino acid.
Thème
Documentation
Dans la même collection
-
2.7. The algorithm design trade-off
RECHENMANN François
We saw how to increase the efficiencyof our algorithm through the introduction of a data structure. Now let's see if we can do even better. We had a table of index and weexplain how the use of these
-
2.1. The sequence as a model of DNA
RECHENMANN François
Welcome back to our course on genomes and algorithms that is a computer analysis ofgenetic information. Last week we introduced the very basic concept in biology that is cell, DNA, genome, genes
-
2.10. How to find genes?
RECHENMANN François
Getting the sequence of the genome is only the beginning, as I explained, once you have the sequence what you want to do is to locate the gene, to predict the function of the gene and maybe study the
-
2.5. Implementing the genetic code
RECHENMANN François
Remember we were designing our translation algorithm and since we are a bit lazy, we decided to make the hypothesis that there was the adequate function forimplementing the genetic code. It's now time
-
2.8. DNA sequencing
RECHENMANN François
During the last session, I explained several times how it was important to increase the efficiency of sequences processing algorithm because sequences arevery long and there are large volumes of
-
2.2. Genes: from Mendel to molecular biology
RECHENMANN François
The notion of gene emerged withthe works of Gregor Mendel. Mendel studied the inheritance on some traits like the shape of pea plant seeds,through generations. He stated the famous laws of inheritance
-
2.6. Algorithms + data structures = programs
RECHENMANN François
By writing the Lookup GeneticCode Function, we completed our translation algorithm. So we may ask the question about the algorithm, does it terminate? Andthe answer is yes, obviously. Is it pertinent,
-
2.9. Whole genome sequencing
RECHENMANN François
Sequencing is anexponential technology. The progresses in this technologyallow now to a sequence whole genome, complete genome. What does it mean? Well let'stake two examples: some twenty years ago,
-
2.4. A translation algorithm
RECHENMANN François
We have seen that the genetic codeis a correspondence between the DNA or RNA sequences and aminoacid sequences that is proteins. Our aim here is to design atranslation algorithm, we make the
Avec les mêmes intervenants et intervenantes
-
1.7. DNA walk
RECHENMANN François
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
-
2.6. Algorithms + data structures = programs
RECHENMANN François
By writing the Lookup GeneticCode Function, we completed our translation algorithm. So we may ask the question about the algorithm, does it terminate? Andthe answer is yes, obviously. Is it pertinent,
-
3.4. Predicting all the genes in a sequence
RECHENMANN François
We have written an algorithm whichis able to locate potential genes on a sequence but only on one phase because we are looking triplets after triplets. Now remember that the genes maybe located on
-
4.7. Alignment costs
RECHENMANN François
We have seen how we can compute the cost of the path ending on the last node of our grid if we know the cost of the sub-path ending on the three adjacent nodes. It is time now to see more deeply why
-
4.9. Recursion can be avoided: an iterative version
RECHENMANN François
We have written a recursive function to compute the optimal path that is an optimal alignment between two sequences. Here all the examples I gave were onDNA sequences, four letter alphabet. OK. The
-
1.2. At the heart of the cell: the DNA macromolecule
RECHENMANN François
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
-
1.10. Overlapping sliding window
RECHENMANN François
We have made some drawings along a genomic sequence. And we have seen that although the algorithm is quite simple, even if some points of the algorithmare bit trickier than the others, we were able to
-
2.9. Whole genome sequencing
RECHENMANN François
Sequencing is anexponential technology. The progresses in this technologyallow now to a sequence whole genome, complete genome. What does it mean? Well let'stake two examples: some twenty years ago,
-
3.7. Index and suffix trees
RECHENMANN François
We have seen with the Boyer-Moore algorithm how we can increase the efficiency of spin searching through the pre-processing of the pattern to be searched. Now we will see that an alternative way of
-
4.4. Aligning sequences is an optimization problem
RECHENMANN François
We have seen a nice and a quitesimple solution for measuring the similarity between two sequences. It relied on the so-called hammingdistance that is counting the number of differencesbetween two
-
5.2. The tree, an abstract object
RECHENMANN François
When we speak of trees, of species,of phylogenetic trees, of course, it's a metaphoric view of a real tree. Our trees are abstract objects. Here is a tree and the different components of this tree.
-
1.5. Counting nucleotides
RECHENMANN François
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,
