Day 18 DNA!!

1. Explain the significance of Mendel. 
Gregor Mendel's experiment of breeding pea plants showed that traits from parents are present in the offspring. His tests supported Darwin's theory of "blending inheritance." It was later proved that the changes in the pea plants were due to the changes in the DNA through generations.

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

James D. Watson and Francis Crick discovered the structure of a double helix. 

3. Explain each of the five examples of variations that occur to DNA and give an example of each.
 a. Point Mutation - a single base pair change. the mutation inactivates a gene for a signaling molecule.
ex. Dogs are moderately more muscular when only one copy of the gene is disabled. 

b. Insertion- when multiple base-pair sequences are inserted into a gene. 
ex. when 800 base-pair sequences are inserted into a pea produces peas that are wrinkled rather then smooth. The intruding DNA disables a a gene necessary for starch synthesis, affecting the sugar and water content. 

c. Gene-Copy number- When you copy errors during cell division to duplicate entire genes.
ex. where the enzyme salivary amylase  is copied 10x more in humans than chimpanzees, making humans the better starch digestors.

4. What is evo-devo?
Evo-devo is a subspeciality in evolutionary biology that concentrates on studying the effects of changes in important developmental genes and the role they play in evolution. 

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

Day 17- Traces of a Distant Past

Traces of a Distant Past is all about how DNA gives us a clearer picture of the multimillennial trek from Africa all the way to the tip of South America. It goes on to explain the multiple studies over the differences of human genome from person to person. Almost all DNA, at least 99.9 percent of it, is the same from person to person, but by studying the differences in the last .1 percent, scientists are hoping to uncover clues about the journey our ancestors ventured on from continent to continent. 

Only recently have scientists began widening their focus range from only a few isolated stretches of DNA to study hundreds of thousands of nucleotides scattered throughout the genome instead of just the comparisons between let's say East Africans and Native Americans. Scientists are able to follow the breadcrumbs that were left behind by our ancestors. 

From the video, "Journey of Man", we learned that Y chromosome gives us an opportunity to follow our migratory heritage back to "Adam," just as earlier work in mitochondrial DNA allowed the identification of Eve the mother of all homo sapiens. 

In our Y Chromosomes and our Mitochondrial DNA, scieintists are constantly looking for genetic markers - characteristic patterns of nucleotides - and how they differ from population group to population group. 

After piecing this information together, Scientists are then able to piece together a map of the travels our ancestors took to spread throughout the world. 

(below) 

The difficulties with DNA are that unlike Fossils, the rate of mutation can differ from one strand to another, causing inconsistencies. Yet, fossil remains are too rare, and often incomplete. 

To fill in the missing blanks that DNA and fossils can't clearly fill, Scientists use more DNA from microbes that hitch rides on humans. (ie. lice, bacteria, and viruses) 

Using this information, Scientists have formulated the Out-of-Africa theory. From 50,000 to 60,000 years ago, our ancestors traveled out of Africa, and eventually overtook the Homo Erectus species and converged into once species. Through interbreeding, the species were able to remain one and the same, making us part Neanderthal.

Then there's the multi-regional theory, which states that over the past 1.8 million years ago, that our ancestors evolved from Asia, Europe, and Africa, and eventually emerged as Homo Sapiens. 

The Occasional interbreeding made sure we didn't evolve into multiple species. 

There is evidence that supports interbreeding from both theories, many fossilized skeletons of H. Sapiens have features reminiscent of earlier hominids. Scientists estimate that the two genomes are 99.5 percent alike. Yet studies have shown that the Y chromosones in Neanderthals differed from ours.

Scientist would like to use this information and these theories to claim that there is no race. We are all brothers to each other, there is no genetic differences, only geographic gradients.