Day 19-Jump Into the Gene Pool

Survival of the Sickest Ch.6 Summary:

The first vaccines were discovered by a man named Edward Jenner, an eighteenth century doctor. A common disease was cowpox, which many milkmaids had from being around cows. He found that they were immune to smallpox so he then infected a different group of people with cowpox, and found that they were also immune to smallpox. From here, the first vaccine was born. The word vaccine comes from the Latin word vacca, meaning cow, and the Latin name vaccina, meaning cowpox.

Your body contains 46 chromosomes, 23 from your mother and 23 from your father. Within these, there are around 30,000 genes which are organized based on different traits. Although your body has so many genes, only around 3% are actually functioning. The other 97% though, contains important information about how your body works, unlike the misconception that they are "junk DNA."

A scientist named Barbara McClintock disproved another common misconception about DNA from the early 20th century. Through her research and testing on corn, she found that there are genes, which she called "jumping genes," that copy and paste themselves in different places along the chromosomes. She proved that they  were actually intentional mutations, not just random. She found this because they place themselves in certain, particular places and they are triggered by outside influences. She also found that they jump to certain places more than others and they jumped at times of stress.

Another new finding within DNA and mutations is that mutations actually occur outside the germ line all the time. We had thought previously that mutations occur inside the germ line and they affect the entire population and offspring, but this is not the case. For example, Cancer, "which is uncontrolled cell growth caused by a mutation in the gene that is supposed to control growth of cancerous cells" (Moalem, 144). Of course, some forms of cancer are hereditary, but others are caused by factors outside the germ line such as smoking. 

Day 18-DNA

1. Mendel designed an experiment involving crossbreeding pea plants. He bred different variations of the plants, such as tall and short plants. In his findings, he proved that heritable variants are not just blended randomly, but are "discreet entries passed from parents to offspring."  
2. Francis Crick and James Watson discovered the double-helix structure (see image below).
3. Variations:
• Point Mutation- Inactivates the gene, such as in whippet dog, which has a much more slender body than most other dogs.
• Insertion- A new base-pair is inserted into the gene, such as pea plants which have wrinkled skin instead of smooth skin. 
• Gene Copy Number- When entire genes are duplicated, such as in chimps, who have only 1 enzyme to digest green plants where as humans have 10.
• Duplication- Sequences containing 8 or more of the same base-pair, which can cause dark spots on the body.
• Regulatory Changes- A mutation which turns genes on and off, which can cause appearance changes.
4. Evo-devo is the study of the role that the effects of changes in important developmental genes play in evolution. 
5. If a person stops drinking milk after their infant years, they will loose the enzyme which allows them to digest lactose. Those who do not stop, though, will have an enzyme called lactase, which allows them to drink milk.

Day 17- Races

It is safe to say that different races on earth do not exist. We all originated from one continent; more specifically, one tribe of people. These people, from south-east Africa, are the origin to the human race. In this group of people, we can find features of all different races of people, all in one person. This tribe ventured out of their home to search for something new. Where they were going? They had no idea because they had never been too far away from their home. They started in south-eastern Africa, then moved through the modern Middle-East and on to Asia. After Asia, the tribe scattered out in different directions, and it is here that we find the differences that are used to characterize what modern-society defines as a race.

             

The differences in appearance and traits are caused by genetics or DNA, which are tiny variations in the genetic makeup of a person. As time went on, these variations appeared more and more often, and the gaps grew bigger and bigger between races, until finally, we get to the modern world with hundreds of different races.  All of this is an outcome of natural selection, where nature is the one who decides which traits keep reappearing, and which are not as common. For example, the original tribe of people had a dark skin color. This is because they lived in south-eastern Africa, very close to the equator, and they were hunter gatherers so they were out in the sun a lot. As time went on, though, and they moved out into cooler regions such as Asia, the need for extra protection from the sun was not needed. So the dark skin pigment trait eventually died off due to natural selection.

This happened over and over, traits came and went throughout the world as humans made their way into climates and lands which they were not used to. Eventually, each race would develop distinct adaptations for the environment they were living in, but all of these races can still trace their roots back to the same common ancestor. 

Day 15-Unit 2 Test

Today we took out test for Unit 2.

Day 14-Populaption Genetics

Today we discussed population genetics and how it relates to evolution. We reviewed that natural selection is based on being fit and able to reproduce. We learned that in genetics, there are two types of traits: dominant and recessive. In a dominant trait, there are two genes which could be an AA or Aa, but in recessive traits, the two genes are always aa. Some terms we learned are Genotype: what the genes are, Phenotype: physical traits, and Gene Frequency: the percent of A's and a's in a population. We learned the gene frequency equation, p+q=1, p being the A's and q being the a's. This equation was developed by Hardy and Weinberg, where they changed the gene frequencies into percents, and then to decimals. The fully written out equation is p²+2pq+q²=1. 

Day 13-Natural Selection

We discussed our results from the Brine Shrimp Lab in class today. We observed that most groups had the highest number of swimmers in the 2.0 concentration brine. The reason behind this is that Brine shrimp eggs wait for a specific concentration to hatch. In this batch, the eggs wanted to hatch in a higher concentration. Brine Shrimp live in saltwater lakes such as the Great Salt lake in Utah. In this lake, the concentration of salt in the water is constantly fluctuating. Mineral deposits deep in the lake cause the concentration to go up, but freshwater snow runoff causes it to go down. Due to this trend, the Brine shrimp would have to constantly be adapting if they hatched at random times, but by hatching at a specific one, they create the best chance for surviving to live to an older age.

Day 12-Brine Shrimp Lab

Today in class we began the Brine Shrimp Lab and discussed natural selection. To learn about this, we separated a bag of shells by different characteristics. We learned that nature uses these characteristics for different things, and we can tell where the shells came from by using them. For example, different colors on the shells are used as camouflage, and the texture of the shell can tell what kind of environment it was in (rocky, sandy, etc.). Later we began the lab. We prepared saltwater brines for with different molarities(0.0, 0.5, 1.0, 1.5, 2.0), and poured them into petri dishes. Then, we put some eggs on a piece of double sided tape and stuck it on a microscope slide. We used microscopes to count how many eggs were on the slide and finally put each slide in the petri dishes.

Day 11-Dangerous Foods

Today we went over Ch. 4 of Survival of the Sickest. We learned that all plants produce a toxin as a defense mechanism against predators such as insects, but not toward humans. Although the toxins are not directed toward us, they can still prove to be deadly in some cases, which could include some foods you eat in your everyday meals. For example, tapioca pudding contains a plant called cassava. When cooked and prepared the right way, it can make for a delicious snack, but in its raw form, is found to contain a precursor to deadly cyanide. Another example is a habanero pepper. If you have ever bitten into a raw habanero and felt a fiery sensation on your tongue, you are experiencing the effects of a plants toxin. This toxin can actually prove to be very harmful, by destroying neurons and can even lead to stomach cancer.