Lab Overview +Chapter Summary

Last class we began our pGlo lab, in which we are trying to make our bacteria grow and glow. The lab won't be finished until next class, though, so I'll post all the details next time. For now, here's the chapter summary for chapter 3 of "Survival of the Sickest."

This chapter provided a lot of information on vitamin D. Sunlight helps our bodies to create vitamin D and gets rid of our body's reserves of folic acid. Different populations have adaptations that help protect folic acid but also allow sufficient vitamin D production. Our skin converts cholesterol to vitamin D when exposed to ultraviolet B sunlight (UVB). Skin color is determined by the amount/type of melanin  produced by our body. Melanin, which is made by cells called melanocytes, is a special pigment that absorbs light. Nina Jablonski and George Chaplin charted the connection between skin color and sunlight and produced an equation to show the relationship between a population's skin color and its yearly exposure to UV rays. The chapter also present the final idea that one might be able to reduce their excess cholesterol just by getting enough sunlight to convert it to vitamin D. Interesting huh?

Survival of the Sickest: Chapter 6 summary

     Chapter 6 began by explaining the origin of vaccinations and then used this information to provide the cliffhanger that "genes could change." Then, chromosomes and recessive/dominant genes are explains. It begins talking about non-coding DNA, mitochondria, and notes that DNA hasn't adapted to viruses and bacteria, it has been shaped by it. Next, the book talks about mutations and explains that antigenic drift is when a mutation occurs in the DNA of a virus while antigenic shift is when a virus obtains new genes from a similar strain. The next major topic covered is the "jumping gene," discovered by Barbara McClintock. She discovered this by observing the genetic of corn, in which the plants seemed to be undergoes a kind of intentional mutation. The jumping genes sometimes copy and paste, cut and paste, stay in place, or are removed or suppressed. The two types of jumping genes are DNA transposons and retrotransposons.  Finally the book came back to the topic of the "junk" non-coding DNA to say that transposons are an important part of our non-coding DNA...so perhaps this non-coding DNA is in fact not junk........................

Structure of DNA Day

In class, we reviewed the structure of DNA, using the video we watched for homework, Mr. Quick's powerpoint, and DNA diagrams as a guide. Then, we took out our creative talents (of which I have none) to create a paper model of DNA. Once we were done cutting everything out, we used tape to act as the bonds: 2 pieces for A and T and 3 pieces for C and G.
Next class, we're going to simulate DNA replication, so we started this by "unzipping" or cutting one of our DNA model's bonds where the replicating will begin.

"From Atoms to Traits" Questions

1. Explain the significance of Mendel.

Though Darwin's Theory of Evolution was revolutionary, even he knew that some parts were problematic, especially the theory of blended inheritance. Gregor Mendel's discoveries in 1900 helped clarify this confusion with his pea breeding experiments. Mendel discovered that when true-breeding different types of pea plants the offspring had traits of one of the two parents. When further breeded, both forms of the trait could reappear in future generations without dilution. Thus, Mendel's experiments altered the perception of heritable variants from blendable to entities that are passed down from parents to offspring. He also discovered that though these variants are not always visible, they are always present.

2. Draw the structure of DNA and who discovered this structure.

The double-helix structure of DNA was discovered by Francis Crick and James Watson.

3. Explain each of the five examples of variations that occur to DNA and give an example of each.

1) point mutation (single base-pair change) ~ whippet dogs
2) insertion (insertion of new letters into the sequence) ~ pea plants
3) gene copy number (duplication of entire genes) ~ chimpanzees
4) duplication (error in duplication of letters) ~ pigs
5) regulatory changes (changes in the regulatory regions of a single gene that controls cell division patterns) ~ bushy teosinte and its descendent the modern cornstalk

4. What is evo-devo?

Evo-devo is a subspeciality within evolutionary biology which concentrations on researching the effects of changes in developmental genes and how they relate to evolution.

5. Make a connection between human migration and the mutation of lactose intolerance.

Only a minority of people continue to be able to produce lactase (and thus tolerate lactose) after childhood, and the ability to produce lactase was traced in Europeans to a mutation in regulatory DNA. Cultures, such as East African and Saudi Arabian populations, who herd milk-producing animals are also more likely to have the trait of lactose tolerance.  In "Journey of Man," we learned how African peoples migrated all over the world. This would explain how this trait can be traced from Europe to Saudi Arabia to East Africa.

Finish "Journey of Man"

In this class, we finished "Journey of Man," and though the first part was interesting, I found the second half of the movie to be the most intriguing. Most fascinating to me was Dr. Wells trip to visit the Chukchi people. Their unique and isolated lifestyle coupled with their unique and effective survival techniques was amazing to me. In addition, I had never seen the extraction of DNA from blood, and was interested to see this done in the movie. Overall, I truly enjoyed "Journey of Man," and felt that it throughly covered the topic of genetic and evolution in detail. 

"Traces of a Distant Past"

     The article entitled"Traces of a Distant Past," published in 2008 edition of "Scientific American" by Gary Stix, explores the genetic family tree that begins with the San people of African (as shown in "Journey of Man" and ends with South American Indians. Through artifacts and bones, scientists can trace paths of migration, but can only go so far as these objects are difficult to find. However, by using DNA, scientists can compare contemporary humans to determine how long a population has lived in a region.  After decades of genetic sampling, the latest studies envelop entire genomes and provide maps of human migration across the world. The studies also depict certain adaptations relating to peoples' genes, such as those relating to diet, climate, and disease.

        The article also makes a strong argument that from the genetics standpoint, the differences between all groups or rather ethnicities of people are not all that prominent. In fact, this has sparked a debate over what exactly constitute a race or ethnicity. From the viewpoint of many geneticist, the distinction between human diversity is miniscule.

"Journey of Man"

We started by reviewing the tests we took last class. A bit of a debate broke out about some of the questions and their answer (thinking Devonian vertebrates) but finally everything was resolved.

We then began a movie called the "Journey of Man" in which a geneticist named Dr. Wells sought to trace our earliest descent by revisiting the important landmarks in our evolutionary history. This complements the reading we have been doing on evolution and genetics, and I look forward to finishing the movie next class.

Test 2!

Today we took our test on Unit 2, in which we studied evolution. I loved the essay question from the test, and found it easy to write about. Hopefully all of my studying paid off!

Hardy-Weinberg

We began class by reviewing how our knowledge of genes and DNA relates to differences in traits natural selection:

Next, biology turned into math class (yay!!) as we learned the Hardy-Weinberg formula for calculating allele frequencies. Here are the bare basics you need to know:

      p^2 = homozygous dominant
      2pq = heterozygous
      q^2 = homozygous recessive
      p + q = 1
      p^2 + 2pq + q^2 = 1

See....math is easy (and fun!).

Mating Beads....?

Today we did a lab entitled "Evolution and Gene Frequencies: A Game of Survival and Reproductive Success," which is exactly what is was! We used beads (acting as tigers) to determine the effect of random mating in a population of tigers that possessed a recessive gene. We selected to beads (alleles) at a time and recorded the combination. After we were done we set aside the homozygous recessive "tigers" and threw the others back into the mating pool. After 10 times we compiled our data and determined the that recessive allele never completely disappears, it is always present.

Parents Day!

The first part of Parents Day was spent finishing up our Brine Shrimp lab. We found that the greatest hatching viability of the brine shrimp was in the 0.5% solution. This means that the traits of these brine shrimp are best adapted to survive and reproduce in a solution that is 0.5% salt.

The second half of the day was devoted to observing "attractive" traits in different people. With our parents and peers we were shown pairs of pictures, and for each pair we had to choose which one we found more attractive. Finally, we compiled all of our data to find if the majority of males found females with more feminine or masculine faces attractive and then vice versa.

...Brine Shrimp?

Today we began a lab about natural selection that dealt with brine shrimp. The population of brine shrimp are influence by environmental factors...specifically salinity. In the lab, we used different percentages of salt solution to test how some individuals of the population would be better adapted to develop and survive in the different conditions.  The solutions with eggs need to sit for while, so I'll post results in next post......