Animal Cataloging!

◆EVOLUTION◆

     The past couple weeks in Biology we have been discussing evolution. I’m sure that everyone has at least heard of evolution, but not everyone knows what it’s all about. Evolution is a very controversial topic but this is pretty much what I have learned about it-

     Back in the year of 1801, a man named Jean-Baptiste Lamarck published The Theory of Inheritance of Acquired Characteristics. Later, a man by the name of Darwin pointed out that Mr. Lamarck was wrong. It was Lamarck’s belief that organisms were capable of inheriting acquired characteristics. In other words he thought that an organism could inherit a new or additional trait or characteristic from a parent (seems crazy right?). It was his belief that organisms could alter their behavior in response to the different changes they experienced in the environment. This would modify the individual organism’s organs, which their offspring would then inherit-- now becoming evolution. Many people agreed with Lamarck. Why wouldn’t the offspring have it if the parents did? This, for example, would be as if throughout a man’s life he did body building and lifted weights to become stronger, so when he fathered a child the kid was born with extreme strength like his father’s. Right? NO! This is exactly why there was a flaw in Lamarck’s theory. Lamarck also believed that all organisms continued evolving in an upward direction and never became extinct. He thought that organisms just continued evolving until they were perfect.

     Charles Darwin, however, disagreed and stated that organisms pass on mutations, not acquired characteristics. Since organisms pass on mutations, those mutations can give the organism (and its offspring) a competitive advantage with others of its species. If these mutated organisms do have an advantage, then they have a better chance of surviving and in turn, producing offspring. These offspring have a chance of having the same mutation. If they have the same mutation then they’ll have the same advantage. And if they have the same advantage, then they have the same good chance of surviving. And if they survive, then they produce offspring. The offspring probably have the same mutation which means...well I am sure you get the idea; it just goes on and on.  The point is, with more and more “mutated” organisms that are created they start taking up more room in their enviorment. This means that there is less space in the environment for the unmutated organisms. If the mutated ones have the advantage, then the ummutated ones will slowly die out and be unable to produce offspring. This makes it so that the mutated ones suddenly become the common ones. This is called natural selection. You now know the basic idea to the theory of evolution! Have you ever heard of “Survival of the fittest"? Well, ding ding ding! This is where that comes from!  That phrase may not be “technically” accurate because natural selection is based on reproduction and not exactly survival. Don't get me wrong- you defiantly need survival for reproduction, but just because an organism may survive does not guarantee it offspring. That's the important part!

     “Microevolution refers to evolution that occurs at or below the level of species, such as a change in the gene frequency of a population of organisms or the process by which new species are created (speciation). Microevolutionary changes may be due to several processes: mutation, gene flow, genetic drift, and natural selection.” -(New World encyclopedia) An example of this is the difference of house sparrows in North America. They were originally introduced to North America in the year of 1852 and since then the sparrows have evolved different characteristics in different locations. In the North, the sparrow population has larger bodies than the sparrows in the south. The differences in the two sparrow populations are probably, at least, partially due to natural selection- Bigger bodies are better equipped to survive in the cold temperatures. Since it is easier for the bigger bird to survive in the climates with lower temperature they have more offspring until that becomes the bulk of the bird population. That is microevolution! There are other ways in which this can occur; Genetic drift, for example. Genetic drift is all about the change in the frequency of alleles, due to random chance. Genetic drift has a larger effect within the smaller populations, because even the slightest change in the frequency can have an impact on the overall population. If the population is on the smaller side, then there is an increased chance that rare genotypes in each individual organism will not make it to the next generation. Genetic drift is pretty much saying that some random things will happen to a population to change its entire gene pool.

     There is even another part of microevolution- Gene Flow! Gene flow tells you that the migration of organisms can also have an effect on the gene pool. If you have two populations sharing the same area then they will most likely end up interbreeding. If, in fact, they do interbreed then they have introduced even more genes into the gene pool for both of the populations.

     Macroevolution on the other hand is a little bit different than microevolution. “Macroevolution refers to evolution that occurs above the level of species, such as the origin of new designs (feathers, vertebrates from invertebrates, jaws in fish), large scale events (extinction of dinosaurs), broad trends (increase in brain size in mammals), and major transitions (origin of higher-level phyla).”-(New World Encyclopedia). With macroevolution it’s more like focusing on the soil in which the earth worms live instead of the other way around.

     There are a lot of people who believe in evolution and there are a lot of people that don’t. I believe that it is just a theory, and probably can’t be proven. Through my research I haven’t seen any solid proof that we know exactly what happened. In the Bible it says,” The LORD God formed the man from the dust of the ground and breathed into his nostrils the breath of life, and the man became a living being”, Genesis 2:7. The Bible also says, “So the LORD God caused the man to fall into a deep sleep; and while he was sleeping, He took the man’s ribs and closed up the place with flesh. Then the LORD God made a woman from the rib he had taken out of the man, and he brought her to the man.” Genesis 2:21-22. I believe that what is said in the Bible is true and that is really all that matters to me. After doing my research for this project I do believe in adaptation. Animals need to continually adapt to their environment and there is evidence that they do. Researching evolution, the backgrounds, and the theories behind it, has been very interesting to me and I now know a lot more. In my opinion the issue of evolution will never be settled but will continue to be discussed everywhere.

Works Cited:

"Jean-Baptiste Lamarck." MACROEVOLUTION.NET. Web. 13 May 2011 <http://www.macroevolution.net/jean-baptiste-lamarck.html>

"Examples Of Micro". UNDERSTANDING EVOLUTION. Web. 13 May 2011. <http://evolution.berkeley.edu/evolibrary/article/_0/evoscales_0>

"Evolution". New World Encyclopedia. Web. 15 May 2011.<http://www.newworldencyclopedia.org/entry/Macroevolution> 

GATTACA- You need to watch it!

Well, while I was sitting thinking about blog posts, I realized that I haven't done a good ol' Glog lately. So... here it is! A Glog on GATTACA! (Take that Sierra!) 

Putting Mitosis and Onion Root Cells Together For a Blog :)

Begining note: My apologies. I thought that this blog post was posted a couple months ago. I guess it wasn't :( So here is a very late post on Mitosis! 

In Biology we have been working on having a better understanding of the cell cycle and mitosis. We examined onion root cells with the microscopes and although I was not able to get pictures of what I saw I did find some on the internet to better show the different phases.

The picture on the right shows two onion cells in the first phase of mitosis- Interphase. The nucleus (C) is filled with chromatin. These chromosomes inside it are stretched out so that they cannot be seen individually. The dark spot that you see in the nucleus (I) is the nucleolus. Most cells in interphase have 1 or more nucleoi.
Prophase is the second step of mitosis that you see in the onion root cell on the left. While prophase i soccuring, the chromosomes coil and become visible as pairs that are withing the nucleus. The chromosomes often form an "X" shape. The cell's centrioles move to opposite sides of the cell. Tiny fibers attach themselves to the centrioles of each chromosome forming the spindle fibers that will pull the chromosomes to opposite sides of the cell. During this phase the nuclear membrane disappears.

Metaphase is the next step. During metaphase the chromosomes form a line in the middle of the cell. Now each chromosome consists of two exact copies (clones) of the cell's original chromosome. All of the  copies, or chromatids, are held all together at the centromere.  Metaphase ends when the centromeres are ready to separate and allow the chromatids to be drawn to opposite ends of the cell. (Picture to the right)

That gets us to Anaphase. During this step in mitosis the pairs of identical chromatids separate at their centromeres and are drawn to the opposite sides of the cell by the spindle fibers. This makes it so that each daughter cell will have a copy of the cell's original chromosomes. (Picture to the left) 



Once anaphase is over Telophase begins.  During telphase the handy little spindle fibers break down. In return, a new nuclear membrane forms around the chromosomes in each half of the cell. (Picture shown on right) 





After the division of the nucleus and in the last part of telophase the cell begins to visibly separate into two new cells. The process of dividing the cell in half is called Cytokinesis.  Cytokinesis actually starts hapening during the process of telophase.(Picture to the left) 

DNA Extraction!

Below is a overview that me and Sierra Frentress made about our DNA Extraction Lab! :)

Our Little Friends, Greg and Olga (That poor poor girl!)

Greg and Olga were worried about starting a family because they both had some diseases in their families. They decided to visit a genetic counselor to find out the chances of the diseases showing up in any future children.

Part I: Pedigree Construction

1. I constructed a pedigree for Greg and Olga. Here is what it would look like...

Greg and Olga's Pedigree

Part II: Autosomal Dominant Traits

1) Do autosomal dominant disorders skip generations? 

• Autosomal dominant disorders do not skip generations. 

2) Could Greg or his mother be carriers of the gene that causes myotonic dystrophy?

• No, Greg and his mother don't have the disorder therefore they can not possibly be carriers.

3) Is there a possibility that Greg’s aunt or uncle is homozygous for the myotonic dystrophy (MD) gene?

• No, there is not a possibility. Greg's grandmother would have also had to to be homozygous for the MD gene. You know that she is not homozygous because her husband did not have MD and only two of their four children have the disorder. Therefore Greg's grandmother, aunt, and uncle are all heterozygous.

4) Symptoms of myotonic dystrophy sometimes don’t show up until after age fifty. What is the possibility that Greg’s cousin has inherited the MD gene?

• Well, the good news is, Greg's cousin has a 50% chance of not inheriting the Mytonic Dystrophy gene. The bad news is, she has a 50% chance of inheriting it.

5)What is the possibility that Greg and Olga’s children could inherit the MD gene?

• Happy news for Greg and Olga! There is no chance that their future kids will inherit the MD gene. Neither Greg nor Olga have it so there is a 0% chance of their kids having it. Congrats you guys!

Part III: Autosomal Recessive Traits

1) What are the hallmarks of an autosomal recessive trait?

            -This is what I know:

• The traits are found in the siblings of the person that is affected, but not in the parents or the children of that person (it skips generations).
• Females and males are equally likely to be affected
• It has been found that the recurrence risk for an unborn child of the affected sibling is 25%
• The trait, to the blind eye, may appear as an isolated event in smaller families with only a few children
• The parents of the affected children could possibly be there own "kin". The more rare the trait is in the general population, the more probable it is that inbreeding was involved.

2) What does consanguineous mean? Why is this concept especially important when discussing recessive genetic disorders?

• Consanguineous is a term to describe being related by blood or family. This is important when discussing these genetic disorders because consanguineous mating causes a higher risk of passing the ressesive disorder. 

3) What is it about the inheritance pattern of factor VIII deficiency seen in Greg and Olga’s pedigree that point toward it not being an autosomal recessive trait?

• The inheritance pattern of Factor VIII deficiency points more toward it being a sex-linked trait instead of autosomal recessive, because it is only seen in males on the pedigree.

Part IV: Sex-Linked Inheritance 

1) What are the characteristics of X-linked recessive inheritance?

• Males are more likely to be affected than females
• All the affected males in a family are related by their mothers
• The trait is usually passed down from an affected grandfather to his daughter, who then carries the trait and passes it on to 50% of her sons.
• The trait is never passed directly from father to son 

2) Why does a son never inherit his father’s defective X chromosome?

• A son will always be lucky enough to never inherit his father's defective X chromosome because he inherits Y from his father, not X

3) What is required for a woman to display a sex-linked recessive trait?

• The woman must be homozygous for the sex-linked recessive trait in order to display it.

4) Return to the pedigree drawn earlier for Greg and Olga; mark those persons who are carriers of the factor VIII deficiency gene.

• The people now labeled with the orange dot in the pedigree, are carriers of the factor VII deficiency gene.

5) What is the chance that Olga carries the gene for factor VIII deficiency? Calculate the probability that she will pass it to her offspring. Will male children be affected in a different way than female children?

• There is a 50% chance that Olga has the gene for Factor VIII deficiency. If she does, than there is also a 50% chance that she will pass it on to her children (so half of her children will probably have the gene as well) The male and female children will both be affected in the same way because they both have the same chance of inheriting it.

6) What is the chance that Greg carries the factor VIII gene? Can he pass the gene on to his sons? His daughters? How will each be affected?

• Sadly, it is a 100% guaranteed that Greg carries the factor VIII gene. He can not pass this on to his sons because they inherit the Y chromosome from him- not the X chromosome. Greg can pass the gene onto his daughter, who will then be a carrier and could pass it onto her children.

To get to the website about Greg and Olga, click here- http://www.sciencecases.org/sickness_and_health/sickness_and_health.asp