Source evaluation

ScienceDaily,. (2015). DNA. Retrieved 4 March 2015, from http://www.sciencedaily.com/articles/d/dna.htm

This document is clearly an official document of an english newspaper that is written by scientific people and also this newspaper is updated every day so that is a proof that is official.

The author of this website is wikipedia, this scientific newspaper was buyed by wikipedia in 2011 and as we think they bought this newspaper because it was very productive and also this website only speaks about one important theme that is Science. 

As we can see this text is addressed to an audience of a broad knowledge in the field of science. Specifically it addresses to an age of eleventh grade more or less. This is shown  in the way that the author get expressed and also the vocabulary that in this case he is using.

This text is written in english so we observe that the author could be for another country but, he could want that all the people understand his observation about DNA and also what he thinks. 

In our opinion we think that this website is for giving to the public a great knowledge about DNA and  specially in animals. And also this could help many people to make an investigation about this, as in our case are doing. 

This page shows some features of unreliability because it  comes from Wikipedia, however, as I said before this page can be only uploaded by  files that are well appreciated by the audience.

Genetics Home Reference,. (2014). What is DNA?. Retrieved 5 November 2014, from http://ghr.nlm.nih.gov/handbook/basics/dna

This is clearly an official document, a web page of the U.S. National Library of Medicine.

The authors of this web page are the members of the National Institution of Health, so they know what they are writing about and we can trust the information they are communicating to us through the web page.

Due to the information that is on the website, we can say that it is written for people who have a minimum of knowledge on the subject because it uses specific words and advance vocabulary for the explanations. In any case, although the content has specific vocabulary, it is very well explained and therefore can be understood easily.

This web page explains all about genetics and we will focus on the DNA part to find information about it.

We can say that this source is reliable because it is written by people who understand about the subject because they are experts in health and work in the National institution of Health.

We can also see that the website is constantly being revised by individual members. In this way, the information that appears is always updated. The latest update of the website occurred on 12 August 2014.

Background Information

Background Information:

DNA is formed by two chains which are polynucleotidic which form a double helix. The sugar in
the nucleotides always are in the deoxiribose group, and the bases must be A, G, C and T. This
model was described by Watson and Crick in 1953. Both chains are joined by their bases
(which are joined by hydrogen bonds) and are parallel and anticomplementary.

Complementarity means that if one chain is found, somewhere, the A base, in the same place
but in the other chain the T base will be found. Therefore, in a double strand of DNA, A=T and
G=C. This happens every time except for mutations. So, we can figure out the second strand by
having the first one, and vice versa.
DNA has two fundamental functions on human beings:

1) The DNA in the chromosomes is the material by which genes are formed. It contais the 

information necessary that allows the synthesis of every protein in a living being. This 

genetic information which was inherited from our progenitors must be decodified in 

order to be used by the cell, and this process is realized in tho stages:

- Transcription of the genetic information contained in a gene, which allows the cell to 

copy information from the other chains of DNA and copy them which is RNA.

- Translation of the message from the sequence of RNA bases corresponding to a gene, 

it is realized in the ribosomes, which convert this message into a sequence of amino 

acids from a certain protein. 

2) Replication: each molecule of DNA may originate several replicas of itself. Each cell, 

before its division, copies its genes so that its successors contain the same genetic 

dotation as itself.  Therefore, the genetic information will be transmitted from every 

generation.

(ScienceDaily, 2015)

Variables

Independent variable: The time that the organs are died
How are we going to mesure this? This is going to be mesured by freezing those organs and keep them for  few hours inside that fridge , then we are going to extract the DNA and then mesure by watching it with a microscope. This is going to be repeated with other organs of animal. 

Dependent variable: The quantity of DNA that those organs produce will be the dependent variable because it depends on the time the organs still produce DNA. We will see the amount of DNA the organ produces through the experiment and then through a microscope. We will measure the amount of DNA without alcohol in grams.

Constant variable: The same quantity that we are using with all the different types of  materials. We keep the organs the same in the same environment.

Variables we cannot control: We can't control the time the organs have been dead before we buy them, and we can't know where they have been before their death.

Method

      1) We speak with the butcher

      2) Once we have spoken with the butcher, we investigate without the organs

   

      3) We buy the organs

      4) We put the organs in the fridge covered with a plastic bag to avoid smelling it

      5) Each week we cut a piece a of an organ and we see if we can obtain the DNA

      6) We obtain the DNA through the process stated before

      7) We do the same with every organ until there is nothing left or no DNA is produced

      8) We write down the results

    

      9) We do tables (one per organ)

    10) We do graphs (one per organ)

    11) We compare the results

    12) We figure out which organs produce more DNA than others for longer

    13) We make our own conclusions of why some organs produce more DNA for longer than others

    14) We put it all in the same document so it is organized