Survival of the Sickest Chapter 6

 All human being start off with one cell, or a zygote, that is the product of the union of two other cells, a sperm cell from the father and an egg cell from the mother. That one cell contains every single genetic instruction  to manufacture the proteins used to build a human being. Our genes are organized by twenty- three pairs of chromosomes, so forty- six in total. One set of the chromosomes come from the father and one comes from the mother. They carry instructions for our bodies to carry out tasks. Also, many advances are happening. Scientists now think that "junk DNA" is not useless. Also, evolution is not random  because there are cells that proofread the process of copying genes, and errors rarely happen. Nobel-prize winning scientist, Barbara McClintock found that corn genes mutated faster when the corn was under stress like drought or extreme heat and this is called “jumping genes”, which is when the cell suppresses the proofreading cells so mutation will occur. Viruses also contribute to evolution because jumping genes occur in viruses which is called retrotransposons, there is also another kind of jumping genes called DNA transposons. 

From Atoms to traits

1. Mendel's experiment is important because he was able to get some proof for Darwin's theory of evolution through natural selection. Through his experiment with peas he was able to show us that variants in species are inheritable and that genetic variants reappear in future generations, not blend away.

2. James Watson and Francis Crick were the ones who discovered the double helix structure of DNA.

3. A variation in DNA is called a homopolymer, which are stretches of DNA with eight or more identical letters in a row are prone to copying errors during DNA replication and an example of this is microsatellites which consist of sequences of two or more nucleotides in a row. Another variation is called “jumping” elements, which change gene activity patterns by creating new regulatory sequences, and an example is the wrinkly seeds of peas.Another is when the bases change from A to G, and an example of this is in peas when the variation occurs it shortens growth. Another is the change in regulatory genes that regulate cell division, and an example is the differences between the maize plant and the tesinte plant. Finally, the last one is the variation is change in pigment cell, and an example is the change in human skin color.

4. Evo-devo is the study of the effects and changes in important gene developments and their role in evolution.

5. The ability to digest milk is only found in infants. Different lactose tolerant have different mutations in key regions. Because humans rely on milk, the mutation is still active. 

Founder Mutation

Founder Mutations is the genetic legacy of a founder of a population, which is passed on through inheritance. People who have founder mutations have damaged DNA embedded in a larger stretch of DNA that is identical to that of the founders. This region of shared DNA is called a haplotype. If you share a haplotype with someone then that means that you guys share a common ancestor and are related. One can determine the age of a founding mutation by the length of the haplotype because over time the haplotype becomes shorter. The haplotype in the founder is an entire chromosome that contains the mutation. The hot spot is different because it is a DNA base pair that is prone to mutation. People who have hot spots are not related, so the rest of their DNA varies, unlike in people who have the founder mutation that do share some DNA.

The reason people have genetic mutations is because the mutations gives people an advantage in warding off diseases. If you have the dominant trait of a mutation you could have an unwanted disease, but if you have the recessive trait, that will help you. People who carry a single copy of the sickle cell disease are much less likely to contract malaria. Individuals with two copies of the mutation die off soon, but people with one copy live longer because their copy helps them fight off diseases. This is called balancing selection. This chart will give more examples of how mutations can help:

            The ability of identifying founder mutations helps doctors identify certain patients to be tested for diseases. Also, geneticists can use the haplotype to trace back the origins of populations and their migration tracks. They can look back at a certain time and region to help find the connections between all humans.  

Chapter 4 of Survival of the Sickest.

Then next class we worked on our paleontology projects. The class after, our homework was to read chapter 4 of the book Survival of the Sickest. In this chapter, we learned about fava beans, how genetics come into play with evolution, etc. People with G6PD deficiency (so they can't eat fava beans or they'll die), have less chance of getting malaria because mosquitos are repelled from their blood by making the red blood cells a less hospitable place for the disease. Their genetic mutation is also a benefit. To sum up nicely about the chapter, I wrote a poem:

Oh great almighty fava bean,

How can you be so nice and mean?

You make people sick and you make people heal,

All from just eating your meal!

The enzyme deficiency in 400 mil,

Is just as useful as taking an anti-malaria pill.

Mosquitos repel from favism.

Which gives us optimism.

Yet some of us with G6PD deficiency,

Are killed by fava beans with great efficiency

What can we really trust?

Our genetics will tell us whom we must.  

Also we learned that plants have way of fighting off predators by producing chemical and toxins that would repel them. The cassava plant produces cyanide, and the nightshade plants, hot peppers, produces a sticky poison called Caspian, and Jimsonweed produces hallucinogens.  

Then picked what animals we were going to create transitional fossils for in our paleontology projects. My lab partner and I chose to do Phiomia, Early Elephants.

Tiktaalik!

For homework, we had to read chapters 1,2, and 11 in Neil Shubin's Your Inner Fish. The chapters talk about his discovery of the transitional fossil called Tiktaalik.

Tiktaalik is important because it not only has gils and webbed feet like a fish, he has limbs, a flat head, and a rotating neck, like a land animal (amphibian). The discovery of Tiktaalik was about serendipity and careful planning. To find your specific fossil, you need right time period or age of the rock, sedimentary rock, and exposer. 

We also learned about homologous structures. This means that the structure of the bones is similar, but the function and purpose is different. Also, it shows us that the animals with the homologous structures share a common ancestor.

 Then we took a quiz on this stuff.

Test!

Next, class we had a test on Unit 1. It was on diffusion and osmosis, basic chemistry, properties of water, organic compounds, etc. It was okay.  

class #8

During class, we reviewed for our upcoming test. We reviewed properties of water, basic chemistry, diffusion and osmosis, cell membrane, its structure and functions, organic compounds, and macromolecules. We also went over structures of formulas.

After reviewing, we took a quiz which really prepared us for the test. Right as I was turning in my quiz, the fire alarm went off. What timing. Soon we were evacuated because there was a huge fire next to campus. It was a very eventful day.