Simple (5th grade) questions on DNA

[berlinbrown]

I am still trying to wrap my brain around DNA.

 

It looks like the DNA strands contribute to the protein synthesis process. But how can we go to DNA synthesis to proteins to...a person's eye color being a certain color.

 

Maybe it is the protein synthesis part that I am missing? Do the proteins created for the cell give the cell certain properties such that the cells making up the eye will have the color?

 

Another question, do scientists know that this particular sequence of DNA contributes to protein generation for these particular cells. For example, is such that: DNA Sequence 1,2,3 contributes to eye color, etc? Is it that simple?

Edited February 7, 2011 by berlinbrown

[NTettamanti]

It looks like the DNA strands contribute to the protein synthesis process. But how can we go to DNA synthesis to proteins to...a person's eye color being a certain color.

 

Maybe it is the protein synthesis part that I am missing? Do the proteins created for the cell give the cell certain properties such that the cells making up the eye will have the color?

 

From my very limited knowledge, I do believe you have this correct. The actual pathway from the DNA to a protein looks like this: First, the DNA where the gene is located must be transcribed onto messenger RNA, mRNA. This mechanism is transcription.

 

The second mechanism used is translation, where the mRNA is used as a template to create a protein. The genetic code with three nucelotides at a time (all three are referred to as codons) by the transfer RNA, tRNA. The tRNA binds to the codons, and then the ribosomes synthesize new proteins. These proteins can then be used for various purposes: from benefiting the cell to expressing a gene.

 

Another question, do scientists know that this particular sequence of DNA contributes to protein generation for these particular cells. For example, is such that: DNA Sequence 1,2,3 contributes to eye color, etc? Is it that simple?

 

Geneticists can pinpoint which sequences of DNA code for different proteins (that, in turn, express some sort of gene). Specifically, your question about eye color can be answered here: http://news.bbc.co.uk/2/hi/6195091.stm. The Human Genome project has mapped the sequences of chemicals that make up DNA and mapped (the approximately) 25,000 genes that a human has. In short, we know all of the sequences, but we don't necessarily know what each one does; however, we can figure this out by a bit of lab work (as was done for eye color).

[alpha2cen]

Another question, do scientists know that this particular sequence of DNA contributes to protein generation for these particular cells. For example, is such that: DNA Sequence 1,2,3 contributes to eye color, etc? Is it that simple?

 

From the embryo cell, many cell devision make many kind of tissues and organs in the human body. All cells in the human body have same DNA code without sex cell.

The differences is epigenetics, i.e. DNA methylation, etc. depress gene expression. Most precision way to know which DNA contribute to certain protein expression is looking at m-rna profile. Color related genes have been known already. Look at NIH web site.

Edited February 15, 2011 by alpha2cen

[Horza2002]

Every cell in your body (brain cell, muscle cell etc) has exactly the same set of DNA as all the other cells...what makes them different is which genes are "turned-on" and which are not. In this case, the proteins that are formed control the properties of the cell and what it will do etc. And as NTettamanti said, the Human Genome Project identidifed several thousand genes and what theire role in the human body.

 

With respect to eye colour, there are several different "kinds" of the gene that code for eye colour; called allele's. The different eye colours that you have depend on which allele's you recieved from you parents.

[Thewar]

Okay....first of all the central dogma of biology: DNA -> RNA -> protein. DNA is where information is stored. How the information is stored in the DNA is known as genotype. Protein is used to express this information. What information is expressed is known as phenotype. Basically, you can think of the genotype as a program codes in the computer (you can't see it)...the phenotype is the output of the program which is the program itself. The DNA is one of the most important parts of the cell. It needs to protected well. Cancer is one of the results if DNA is damaged and the cell loses control of its replication rate. But that aside, RNA is made from DNA and transcribed into the protein using what are known as ribosomes. The genotype of an individual decides what kind of protein is expressed. The gene coding for the eye is a polymorphic allele (an allele that has 2+ types, so we get a wide range of colors).

 

If you continue in biochemistry, you will learn that by changing the protein is small ways, you are able to change the phenotype. I'm going too in-depth for a 5th grade genetic answer, but basically each eye color is a slightly different version of a protein.