Science Buddies: "Ask an Expert"

I am doing this experiment, it is called "From Genes to Genetic Diseases: What Kinds of Mutations Matter?" Is there a scientific form of question like "how does...... (Independent Variable) affects(The dependent Variable）Can the question be like this. How does the type of mutation affects dysfunctional protein. What is the independent and Dependent Variable?


Please help, I NEED this tomorrow!!! Than you very much.

Think about the definitions of independent and dependent variables. The independent variable is the one thing that you're changing in the experiment. You keep everything else the same between trials and then the result is your dependent variable.

Let's say you want to test the effect of pedaling RPMs on bicycle speed. You might put some sort of counter on the pedals, then pedal at 10 RPM. Watch the speed on a speedometer. Then pedal faster, say 20 RPM. Read the new bicycle speed. When you pedal faster, what happens to the speed of the bicycle? What is the independent variable in this test? What is the dependent variable? Do you see a relationship between the independent and dependent variables?

In your experiment, can you identify the independent and dependent variables? Once you do that, the question may be more clear.

Thank you, can the question be like this "How does the type of mutation affects dysfunctional protein."?

A good question has a real answer, is testable using the scientific method and leads to a hypothesis that can be shown to be true or false. The form of your questions is fine - does it meet those tests? What sort of mutation? Is the effect a dysfunctional protein? A disease? If changing which genes are defective will cause different diseases is what you want to test, does your question make that clear?

The one key point you need to remember in genetics is that only some mutations will result in dysfunctional proteins. Changing a base pair in the DNA sequence that codes for a functional protein may have no affect at all or it may result in a totally screwed up protein. Many scientists study how a protein works by deliberately substituting one amino acid for another or by deleting an amino acid completely. Remember that it takes a codon of three DNA base pairs to stand for one amino acid so changing any one of those three DNA base pairs to a different one can change the amino acid (http://en.wikipedia.org/wiki/Genetic_code).

There are three main types of mutation that alter the base sequence of DNA:

1. Missense - substitutes the wrong base, a C instead of a T for example, which can change the amino acid--may be functional or not
2. Nonsense - changes an amino acid codon to a stop codon like UAG which terminates the protein before it is completely synthesized--dysfunctional
3. Insertion or Deletion - this alters the reading frame, the order in which the triplets are read and really messes up a protein--totally dysfunctional

I hopes this helps focus your thinking about what is the independent and the dependent variables and how that ties in with your hypothesis.

If you need more help let us know.

Good luck!

Sybee

Thank you Just to make sure if my variables are correct. The independent variable for this experiment is the genetic disease cystic fibrosis. The dependent variable is the dysfunctional protein.

Yes, the protein, whether it is dysfunctional or not.

To tie it put. The question can be "How does the mutation of cystic fibrosis affects the (dysfunctional) protein.
Do I have to add anything to make it sound more scientific?
Base on your opinion, What do you think the question should be ?
Thank you very much

If you've read through any questions here, you know we can't write your question for you. But don't mutations happen to genes, and the dysfunctional proteins that *might* result from those mutations cause specific diseases?

You might want to consider the different functions of the protein involved, and you could hypothesize how your mutation affects a specfic protein function. Since mutations often involve replacing one amino acid for another, and amino acids often have different chemical properties, you could speculate how the new amino acid may affect protein shape. Protein function depends on protein form. For example, the sickle shape of RBCs in those with sickle cell anemia is due to the replacement of a polar acidic amino acid with a nonpolar amino acid that cannot engage in the same intermolecular actions as the amino acid it replaced. Consequently, the protein folds incorrectly, and the RBCs falter in transporting oxygen. Thus, you might want to consider the functions of the wild type protein and the chemical properties of the wild type and the mutated protein when developing your hypothesis.