DNA extraction

In Mr. Wong's bio class, I extracted DNA from a strawberry.

After getting a strawberry, my group threw it into a special mixture and crushed the strawberry. Then that was funneled onto a tube which had rubbing alcohol added to it. After shaking the tube the DNA rose to the top.

The tiny white particles on top are strawberry DNA.

After observing, I answered these questions:

- What does the crushing/ smashing do?

It mushes up the strawberry so anyone could easily access the DNA. Crushing the berry moves the DNA to a better place for us.

- What does the extraction buffer do?

The buffer isolates the DNA from the rest of the strawberry so it is separate. Just like the crushing, this is just to collect the DNA easier

- What does the gauze do?

It lets small parts get into the tube so only wanted components get collected. It keeps out the chunks.

- What did you observe? What is the DNA?

Pink fluid separated into clear/ white particles on the top and pink liquid on the bottom. The small white stuff on the top is the DNA.

- What does the alcohol do?

The alcohol separates the DNA. It changes the relative weight of the DNA to the rest of the fluid so the DNA rises. It just enhances the separation between DNA and strawberry juice

Genetic Traits

When learning about genes and alleles in science today, we looked at nine specific traits we had and assumed our genotypes based off of our phenotypes. For example, I have attached earlobes, a recessive trait. This means that my genotype is aa. My mom has detached earlobes (picture below) and my dad has attached earlobes. Based on deduction and logical reasoning, I know that my mom's genotype is Aa, while my dad's is aa. Here is a genetic family pedigree showing that.

Here are some questions asked and my answers to them:

Q1: Is it true that dominant phenotypes are always the most common in a population? Explain your answer,

No. In populations with only recessive alleles, dominant phenotypes are not common. In most populations when alleles are spread, dominant traits are more likely to show.

Q2: What determines how often a phenotype occurs in a population?

How often a parent has a phenotype/ genotype and passes it on to the next generation. It is all up to the parent because they are the ones who pass their genes to the next generations.

Q3: Is it possible to determine the genotype of a person showing a dominant phenotype? A recessive phenotype? Why?

Yes for both. For the first question, you can look at the parent generation or the generation after and use that information with deduction to find a person's genotype if dominant. Sadly, this doesn't always work as there are inconsistencies (such as you can't tell the difference between homozygous dominant and heterozygous just by looking at someone).  If Homozygous recessive, you can tell the genotype just by looking at someone because recessive traits must have two recessive genes and nothing else.