Frederick Griffith and the Transforming Principle

Have you ever wondered who was the first to discover something, that experiment did, and with that logic did? For those who have studied biology have surely heard of Griffith experiment!
Frederick Griffith was a medical officer engaged in the study of the bacterium pneumoniae: Streptococcus  pneumonia.
  In 1928suggested that there was a transforming principle that did change a strain of bacterium to another! He took a strain of pneumococcus bacteria, called S (S = Smoth, smooth) producing bacterial colonies smooth and shiny, but highly infectious and a strain called R (R = rough), whose colonies are wrinkled but harmless. Well, what did he do?
There are two versions of the S strain, IIS and IIIS, and an occasional strain S can change in strain R, and never by IIR to IIIS. The two strains differed in that the S strain IIIS caused the death of infected mice, which occurred in mice infected with strain IIS.
He injected in mice a mixture of live bacteria IIR (non-virulent) and with the heat-killed bacteria of type IIIS. All mice were killed by live bacteria which drew type IIIS, bacteria that could not be created for type-specific mutations by IIR.
Griffith concluded that some bacteria were transformed by IIR components of bacteria IIIS, material that he called Transforming Principle.
Then there were many researchers who resumed his experiments to understand the cellular components that allows the transformation, experiments such as Avery, Hershey and Chase experiments which I'll discuss in the future.

the DNA, the deoxyribonucleic acid ..

 

The earth 4.5 billion years, and presumably life appeared between 3 and 4 billion years ago. How did life I will talk about in another post, as it has created the DNA, that union of fundamental molecules that transmit the information necessary for life. Let's see what it looks like DNA. The structure was discovered in 1953 by J.Watson and F. Crick and with the help of R.Franklin. Unfortunately, all we remember that the discovery was made only by the first two scientists, but in reality much it is due to Franklin, who died before receiving the Nobel personally along with his colleagues.The DNA (deoxyribonucleic acid) is composed of monomers called nucleotides from a pentose, the deoxyribose (red circle), a nitrogenous base (circle rooster) and a phosphate group (green circle). The DNA has a double helix shape, ie there are two filaments that are wound connected to each other thanks to the nitrogen bases, The two strands follow two opposite directions, calls the 5 'and 3', which serve to give the direction to the processes in which the DNA is involved, such as duplication and transcription. Consider a single filament and see how he is both chemically and its structure in space. The nucleotides are linked together via the covalent bond between the phosphate group of a nucleotide and the carbon of the other nucleotide, called phosphodiester bond. The phosphate group (PO42-) is linked to the 5 carbon sugar, while the nitrogenous base is linked to the carbon 1.

 The nitrogenous bases are divided into two groups, purines and pyrimidines: the first are the Adenine (A) and Guanine (G), the latter are the Cytosine (C) and Thymine (T). These four nitrogenous bases do not join to case, but may bind to each other only in accordance with the sequence obliged CG, TA. The linear arrangement of these bases damage to the cell the information that serves, in fact, a gene is composed of thousands of purines and purimidine, and according as they are placed can give information or the other.The DNA looks like in the image:
The base pairs are spaced apart by 3.4 nm, thus leading to the formation of two grooves, one major and one minor. The two grooves are very important for the binding of macromolecules necessary for the function of some processes.But it is disposed in the cell's DNA? Assuming that in nature there are two types of cells, prokaryotic, without the eukaryotic nucleus and with the nucleus, the DNA we find it grouped within the cytoplasm in the first type of cells and always grouped in the second type, but within a structure called the nucleus. I voluntarily omitted because the viruses are "entities" particolari.M to exist in nature other structures of DNA, both in circular form, as in bacteria and mitochondria, the cDNA, but also snDNA A-DNA and B-DNA, which present difference in space of the grooves, as well as the Z-DNA which rotates clockwise so, then in the opposite direction to DNA.ed other types that will speak in the future
The DNA is said to be supercoiled, ie wound on whether stessto thanks to the proteins called histone and non-histone to form chromatin. All together to form the chromosome. In practice, the DNA strand is wound atorno to the protein, like a yoyo to form a kind of pearl necklace which in turn is raggruppatom called nucleosome. But why evolution has led to what? Serves both to protect this group that the genetic material, which is huge. The nucleosome is arranged in a structure which we call chromosome, what we all know that in humans is in the form of X or Y.In Nature there are other structures of DNA, both in circular form, as in bacteria and mitochondria, but also A-DNA and B-DNA, which have difference in space of the grooves, as well as the Z-DNA which rotates clockwise, then in the opposite direction to the DNA.
In the next post will describe the processes of replication, that is, as the DNA is duplicated, the transcription process, that is, as mRNA (messenger RNA) copies information for Ribosomes, the protein factories, but also RNA and all the processes that occur in cell.

The Kama Sutra of dragonflies

Even before I finished reading the book I was already anticipating its review. A book about nature, animals and plants but also of men. A book to read and re-read a book to recommend, and to give.

I'm talking about the book by Marc Giraud, "The Kama Sutra of dragonflies", 303 pages to be read and reread, in which Giraud shows us, shows us and tells us many oh so many peculiarities of nature around us. At the very beginning, a foretaste, as a small appetizer, that will tell us later, promising fact the phrase: "And to think that there are people in the country is bored ...

I would like to bring a few examples, even if only for incuriosirvi, both for what concerns the book that as regards the nature that surrounds us ... did you know that a louse when it is still in the womb has an embryo inside her body? or that when the caterpillars eat the stem of corn plants, the plants are able to recall the wasps are able to parasitize the caterpillars? ... here is an example of communication from plant to animal!

But still ... that male blue tits smell of the nest with lavender and mint and these perfumes are constantly renewed in order to attract the females not only have the function insecticide and fungicide?

Have you ever wondered then how do the curls to mate? well, if you read the book you'll find out!

This book is also able to reflect on the nature whether in the city or the bush ...

Happy reading!

I'm here

... and I'm here , after long time...
... after reflected I decide to create this blog!
From the title already you understand it will be a blog based on science, science in general and in particular about biology and about biology evolution, my bigger passions!




My name is Sergio Di Matteo, I am graduate student in Biology with specialization in bio-evo... it means animal biology  and biology evolution.

When I was a child always loved and respected the nature, I've always admired, I was fascinated by the insect's world, so small but immensely complex and in the evening I loved watching the constellation in the sky.

When I went to the sea I spent hours and hours with mask and snorkel to wacth, wacth and watch the fish and other sea animals.
The mountain walks were daily and I was spend my free time between trees and paths.
After the hight school I did two years of engineering but then I realized that my interests were differents and thanks to my friend Laura I am incribed at the Faculty of Biology at the university of Study of Milan and for this I will never stop thanking her.
Now every lesson is for me source of information to assimilate with a great pleasure...at the second years I discovered scientists like Stephen Jay Gould, Richard Dawkins, Niles Eldrege and the famous Charles Darwin...love at first sight!

that's it!