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. 

 

Who took Jerell's Ipod?

For this class we were given the option to choose between two labs, and I chose Who took Jerell's Ipod. I thought it world be interesting solving a mystery with science. For this lab we were reviewing the concepts of organic compounds and macromolecules. An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon and hydrogen. Macromolecules, large complex compounds with relatively large molecular weight, in organic compounds are carbohydrates, lipids, nucleic acids, and proteins. 

For this lab, we were testing vegetable oil, glucose, starch form corn or potatoes, powdered egg whites, and water for glucose, starch, proteins, and lipids. We then tested pretzels, butter, jelly, fat free yogurt, beans, and our evidence for glucose, starch, proteins, and lipids. If our results for the evidence matches up with any of the results of the food, we will know who the culprit is. In our case, our evidence matched up with fat-free yogurt, showing us that Ashley was the culprit! To read more in detail about the lab, how to do the tests, and our results, visit my website and read my lab report-https://sites.google.com/site/tanyamalikhonbio/who-took-jerell-s-ipod

Class 6

For class 6, we went over the cell membrane and its structure and function, and a little bit about our house case #1.

The cell membrane is a semi-permeable layer that acts as a "gate keeper" for the cell. It separates the interior of the cell form the outside environments. All living organisms, except viruses, have cell membranes. They can regulate what goes inside and out of the cell based on molecular size and if it is polar or non polar. Cell membranes are made up of thin layers called phospholipid bilayers. Proteins in the membrane transport molecules, chemicals, and information across it. Glycoproteins are important cell membrane proteins because they help with cell to cell recognition.
In animal cells, if the cell and the solution are not isotonic (reached equilibrium) then the cell membrane can burst if there is too much pressure. In plant cells, since there is a cell wall, if there is a lot of pressure exerting from the inside of the circle, the cell wall will exert equal pressure, and the cell membrane will not burst.

 

For House Case #1, we discussed as a class what we thought our diagnosis were. Mine were heat stroke, concussion, and sleep deprivation. We were able to ask Mr. Quick questions about the patient and his medical history. We were also able to request certain tests to be performed. At the end of the class, we were given the results and told for homework to figure out what the patient had. I suspected that he suffered from hyponatremia (over hydration). To read more about my house case #1 go onto my website- https://sites.google.com/site/tanyamalikhonbio/

Diffusion Lab Class #5

Diffusion is the net movement of molecules down their concentration gradient, and it occurs in solids, liquids, and gases. Even though the movement is down the concentration gradient, the molecules can move in any direction as long as the membrane is permeable to the molecule.

On the 4th of September, we explored this topic by performing two labs. In the first lab, we first created "cells" from dialysis tubing containing 15% glucose and 5% starch (8ml). Then we tested them with glucose strips. Then we added 1ml of iodine to test for starch presence. The higher concentration iodine moved into the lower concentration solution in the "cell". Then after 15 minutes, put the cells un a cup with 1ml of Benedict's on a hot plate. This tests for glucose presence.

For the second lab, we had three pieces of differently cut NaOH. First we measured the surface area of the cubes. Then we placed them in beakers full of water and then added a solution. After a couple minutes, we took the cubes out and re-measured the surface area. We observed that the cubes changed from a white color to a pinkish color. Diffusion took place because the molecules moved from the higher concentration solution to the lower concentration NaOH. However, the cubes were not fully pink in the center because we took them out too early enough for diffusion to happen thoroughly.