What we are made of... (Genetics I)

It is hard to imagine that we have resemblances to the humans.

We… 4 legs; whiskers; long tail. You… bipeds; without great amounts of body hair; no tail. No, no, no, no it is nothing that you can imagine at first sight. But we have more in common that you may imagine.

In the end of last year (2007) a group of international scientists finished sequencing the cat genome, this way they can learn what makes a cat, a cat (besides our whiskers and our beauty, of course!).

These scientists think that the cat has around 20,285 genes, approximately the number of genes the human genome has, which is between 20,000 to 25,000 genes, making this one of the most similar genomes to the human one. Even more, they have a lineage conservation to the first mammal ( from which all mammals have derived ), which is 3 to 4 times bigger that the mouse. This allows them to be able to rebuilt parts of the original genome from our information.

This study is now being used to study and find cures to some human infectious diseases as AIDS and Leukemia, which have a counter part in the cat (FIV – Feline Immunodeficiency Virus and FeLV – Feline Leukemia Virus, one day I have to talk to you about them).

The hereditary in the felines works the same as in the humans. We have 38 chromosomes ( the humans have 46 ), organized in pairs from which one pair defines the sex (sex chromosome), and the remaining are called autosomes.

Each chromosome is composed by a long molecule of ADN, that comes from either the mother or the father. AND is composed from genes which are responsible by defining the individuals characteristics. Each gene is composed of several amino acid, bounded in groups of 3. There are only 4 different amino acids that can be bound to create a “dictionary” of 64 possible combinations.

Hereditarily is done by joining ½ of the ADN from the parent to ½ of the mother, this means that each parent gives half of his being to the new offspring. Lets see:

Father: LR Mother: lr

If we consider L as being the left part of the chromosome and R the right part of the chromosome that the parents can give to the offspring, we can end with:

1st chromosome Lr, lR

… plus the other chromosome, making a combination of 4 possibilities.

You humans use this to check the histocompatibility between each of you, so diseases like leukemia can be cured between yourselves.
It would be easy if we would consider that each gene contains and controls only one aspect of the cat, his color, fur, eyes, … this way it would be easy to know how to write cat using this dictionary, but this isn’t that simple, because, different genes in different positions control the same characteristics, making this knowledge almost impossible to acquire.

But learn more in the next posts…

Purrr… see you next time!

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