From Darwin to Mendel to Watson and Crick

1. Explain the significance of Mendel. 

Gregor Mendel was the man who cleared up all misunderstandings about genes and its inheritance. His experiments with peas included tall pea stalks, short pea stalks, wrinkled peas, smooth peas, yellow ones, green ones, etc. He found that, when two true-bred peas were crossed, the offspring would look like one or the other, but when the offspring are further crossed, some traits that had been thought to disappear reappeared again. Before, people had thought that offspring were the perfect cross between their parents, i.e. if a brown rabbit mated with a white rabbit, their offspring would be tan. However, with Mendel's pea experiments, it was revealed that the features weren't the perfect cross, but only inherited some features from one parent and some from another. 

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

DNA was officially known to be discovered by James Watson and Francis Crick, as they were the ones who proposed the double helix theory, but this is not the complete truth. They had taken a photo from Rosalind Franklin, who, after many years of research, had taken a picture of DNA that showed a double helix. Since Franklin would not give the photo to them, they instead asked her assistant, who unknowingly let them into the lab and let them take the photo. 

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

  1) Point mutation: substitution of a single letter for another at a particular position in the polymer. For example, in whippet dogs, a single base pair change makes the difference between a slender silhouette and the hulking animal. The mutation inactivates the gene for a signaling molecule that regulates muscle growth. In animals with both copies of the gen mutated, muscle growth is uncontrolled for lack of “stop “ signal. When only one copy of the gene is disabled, the dogs are moderately more muscular and prized as racers.

2) Duplication of new letters. Sequences containing the same base pair repeated eight or more times, known as homopolymers, are highly prone to copying errors. For example, in pigs, the gain of two additional C-G pairs in such a sequence inactivates a gene for a signal receptor in pigment cells producing light-colored coats.  On the other hand, copying mistakes within individual cells may also cause the duplicated sequence to lose bases, restoring the gene’s function and producing dark patches on the body.  

3) Gene copy number. Entire gens can be duplicated by copying errors during cell division, leading to differences between species and to variation among members of the same species. The genome of chimpanzees, which eat green plants, normally contains just a single gene of the starch-digesting enzyme salivary amylase, whereas humans can carry up to 10 copies of the gene.

4) Insertion of new letters. For example, in pea plants, an 800-base-pair sequence inserted into a gene produces peas that are wrinkled rather then smooth. The intruding DNA element disables a gene necessary for starch synthesis, altering the peas’ sugar and water content. Such mobile elements are seen in the genomes of most multicellular organisms, including humans.

5) Regulatory changes. Mutations in the DNA that controls when and where genes are activates can produce profound trait changes by altering the formation of entire body parts during the organism’s development. Changes in the regulatory regions of a single gene that controls patterns of cell division during stem development account for much of the shape difference between the bushy teostinte plant and its descendent, the tall modern cornstalk.  

4. What is evo-devo? 

It is a subspecialty within evolution that concentrates on studying the effects of changes in important developmental genes and what role they play in evolution. 

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

Lactase, an enzyme produced in the intestines, helps infants and children to digest lactose in milk. However, this enzyme is only in children, so adults usually lose the ability to digest lactose-- only a small number of them can still digest it. In 2002, however, it was discovered that in East African and Saudi Arabian populations, who usually herd milk-producing animals, have the trait of lactose tolerance risen slowly but surely many times in the past 9,000 years. Therefore, as people from Africa started migrating to different areas 50,000 years ago, the trait of lactose tolerance was passed down through the Y chromosome, which is why it is traced in Europe, Saudi Arabia, and East Africa. 

Evolution Reflection

All the people in the world are descended from one mother—a Mitochondrial Eve. She wasn’t the only person at the time, but her lineage was the only one that survived and lived on to reproduce and pass on useful genes. Her lineage can be traced through DNA genetic markers, which lead the scientists to another way to trace human origin—the Y chromosome that is passed on from father to son. The chromosome contains tens of thousands of nucleotides, which makes it easier and more efficient to distinguish one part of the evolution tree from another. By using the nucleotides, scientists have been able to map out a hesitant yet clear path of how humans migrated and traveled from one place to another.
            For example, humans first originated from Africa from one mother, as stated in the previous paragraph. Then, one group of super strong, super smart humans left their homeland in search of either greater things or just to satisfy their curiosity. Along the way, they stopped for a few generations and reproduced, therefore leaving the population there to survive and flourish rapidly. How did they get all around the world when there were seas and oceans in the way, though? In the video Journey of Man, the narrator explains that there was an Ice Age at the time, so the waters in the ocean were all trapped in ice, leaving more land exposed, and making it easier for the ancestor humans to travel from one place to another.
            The origins of humans come from a tribe of present-day Africans called the San Bushmen. They are an isolated tribe, and have never mingled much with outsiders. By looking at their faces, you can see different type of facial and body features from around the world. Why did some of them stay, though? Since some saw it fit enough to leave, why didn’t they all leave and find a different place to live? Was there something preventing them from leaving, or were the people who left bored of their homes? Whatever the reason, the San Bushmen were the original humans who were part of the people who left Africa in search of other places. In the video, a woman had Asian-looking eyes, high Mongolian cheekbones, and a European face shape. With so many different features in one face, there is no doubt that these people were the originators of humans.
            What made the super strong, super smart people leave? Were they simply bored with their lives already? Or were there environmental conditions that required them to leave? The answer doesn’t seem to be getting any closer right now, but in the future, scientists may figure out something that makes more sense. As of right now, the only things that we know and are available to us is the fact that once the super strong, super smart humans left, they travelled the world on exposed land during the Ice Age, leaving people in places to flourish and spread out. 

Macromolecule Lab Part 1

Part I. Intro to macromolecule

A macromolecule is a molecule that is commonly created by polymerization of smaller subunits. Macromolecues have three conventional biopolymers (nucleic acids, proteins, and carbohydrates) as well as non-polymeric molecules with large molecular mass such as lipids and macrocycles.

The individual constituent molecules of macromolecules are called monomers.

In-class notes
Cell membrane serves as a security wall.
The sturcture of cell membrane:
a) bilayer, which is a phospholipid, made of lipids (hydrophobic) and a phosphate head (hydrophilic)
b) Imbedded proteins that serve to transport messages and recognizes other cells that are allowed to pass through the cell membrane.
c) cholestera (fluid shape)
d) carbohydrate (C, H, O)
e) Glycoprotein, which is a combination of imbedden protein and carbohydrates--chemically communicates with cells.

Survival of the Sickest Chapter 4--Hey, Can You Do Me A Fava?

This chapter of Survival of The Sickest was about fava beans. Fava beans are, as the name suggest, beans. They can be eaten, but can be harmful and even deadly to some people--people who have favism. The beans contain two sugar-related compounds called vicine and convicine. These produce free radicals (un-paired electrons) and the people with favism have hydrogen peroxide formed from the vicine and convicine, which then attacks the red blood cells, breaking them down.

Favism is a hereditary disease, passed on from parents to children. It is more common in males, though, because of the X chromosone. Favism is also known as G6PD, glucose-6-phosphate dehydrogenase deficiency. People with G6PD have a different circulation of sugar in their body. More red blood cells in their bodies will be destroyed because of G6PD. Therefore, when they eat fava beans, which destroy even more red blood cells, they can die.

This chapter also explained about the different types of self-defense systems in plants. Plants can be toxic, like spicy pepper, which has capsaicin in it. Capsaicin makes the pepper, spicy, but it is also considered poison. People then developed an ability to taste the bitterness of poison, which allowed us to survive longer and reproduce. However, just because we can eat something, doesn't mean that it's safe! Like fava beans. And sometimes if you maybe overdose of super spicy chili peppers.

Yer Inner Fish (All Bony and Everything LOL JK)

So the other day, we had to read a few chapters of "Inner Fish" for homework. It was a really interesting book, mostly because it was detailed about how and where and when Dr. Shubin found the Tiktaalik, and the trouble he went through trying to determine all the factors of a fossil. The chapters were mostly about his finding of Tiktaalik, the transitional fossil between fish and amphibians.

Tiktaalik, unlike fish, has eyes on top of its head rather than on the side, and has a flat skull, which allows it to see predators above water before they come. It also has a bit of a neck, which means that it can look around without wiggling its whole body like a fish. Another amazing feature of the Tiktaalik that makes it the perfect transitional fossil is the short forearms it has. With forearms, Tiktaalik can do push ups, which allows it to escape easily out of mud or sand, and therefore survive better against predators. Unfortunately, fish only have boneless fins, which makes them easy prey when they are stuck in the mud or in the sand.