Drafts

For the most part, DNA is found in the B-DNA form.  This means the DNA is forming a right handed helical structure with 10 base pairs per turn.  There are other types of DNA like A-DNA and Z-DNA which can be found in certain conditions.  A-DNA is right handed and has 11 base pairs per turn.  This can be found in places of low humidity.  Z-DNA is a left handed helical structure with 12 base pairs per turn.  This condition is favored in cytosine and guanine rich sequences in a high salt environment.  In addition, Z-DNA occurs in cytosine methylated regions in a low salt environment.  Another condition that DNA has been found in nature is a triple helix.  In this case, a synthetic piece of DNA inserts itself into the major groove of the naturally occuring DNA.  It is sequence specific and certain protiens have been discovered which recognize the triple DNA helix.

DNA is a type of macromolecule responsible for genetic material.  It is composed of monomers known as nucleic acids.  Nucleic acids are formed from thre different subunits: pentose sugar, phosphate group, and base.  The pentose sugar is composed of five different carbons starting with the 1'C where the base is attached.  There is no OH group on the 2'C but an OH group on the 3'C.  The phosphate group is attached to the 5'C.  The base of nucleic acids can either be a purine or pyramidine.  Purines have two carbon rings and are Guanine and Adenine.  Pyramidine bases have a single carbon ring and are Thymine and Cytosine.  Between each nucleic acid, a phosphodiester bond betweeen the phosphate group on the 5'C of one nucleic acid and the 3'C of another nucleic acid holds the strand together.  The phosphate and sugar form the backbone of the DNA strand.  Attaching the two strands together are the bases.  Guanine and cytosine pair together and form three hydrogen bonds while adenine and thymine bond together with two hydrogen bonds.  DNA is a double stranding helical molecule which has ten base pairs per turn.  It is negatively charged as well.  During replication, a semiconservative method is used meaning each resulting strand has newly formed strand and a parent strand

Using a pipet, transfer the cooled contents into a centrifuge tube containing water (1 mL) and mix the contents together.  To see the different layers, add saturated NaCl solution (~2 mL).  After the layers are defined, removed the lower aqueous layer and place it in a waste beaker.  To the centrifuge, add saturated aqueous sodium bicarbonate (~1 mL), mix the solution and remove the lower waste layer.  Repeat this process needs to be done an additional time.   After adding saturated aqueous sodium chloride (~1mL) to the ester, mix thoroughly and remove the lower layer to waste beaker.  From the centrifuge, move the organic layer into a vial and add anhydrous CaCl2 (5 spheres) to remove any remaining water and let stand for five min.  Using a pipet, move the product to a tarred vial and calculate the mass and yield of the product (0.857g, 59.8%).  In addition, perform an infrared spectrometry test and observe the smell coming from the product. 

In the 1940s, a majority of scientists were under the belief that protiens were the macromolecule of genetic material but this theory was in desperate need of scientific support.  Griffith performed an experiment proving the transformability of bacterial genetic material.  His methods were key in determining which macromolecule made genetic material.  First, he started with the controls of his experiment. A lethal S stain of bateria and injected it into mice which died and a nonlethal R strain was injected into a mice which lived.  He then went on the heat kill the lethal S strain and inject it into a mouse which lived.  Then, he took the heat killed S strain and mixed it with a nonlethal R strain and injected it into a mouse.  The mouse died.  Finally, he isolated the mixed bacteria from the deceased mouse and injected it into another mouse and that mouse died as well.  From these results, the transormability of genetic materialm was proved.  These methods were the base of Avery, McCarthy, and McLeod's experiment to determine which macromolecule of the bacterial was transformed. They used fractional analysis to isolate RNA, DNA, protiens, lipids and carbohydrates in the heat killed S strain and mixed those with the non-lethal R strain.  Whichever macromolecule killed the mouse was the macromolecule of genetic material.  DNA was the only macromolecule to result in the death of the mouse.  Other studies were performed in the next years to confirm this finding.

In the 1940s, a majority of scientists were under the belief that protiens were the macromolecule of genetic material but this theory was in need of scientific support.  Griffith performed an experiment proving the transformability of bacterial genetic material.  His methods were key in determining which macromolecule made genetic material.  First, he started with the controls of his experiment. A lethal S stain of bateria and injected it into mice which died and a nonlethal R strain was injected into a mice which lived.  He then went on the heat kill the lethal S strain and inject it into a mouse which lived.  Then, he took the heat killed S strain and mixed it with a nonlethal R strain and injected it into a mouse.  The mouse died.  Finally, he isolated the mixed bacteria from the deceased mouse and injected it into another mouse and that mouse died as well.  From these results, the transormability of genetic materialm was proved.  These methods were the base of Avery, McCarthy, and McLeod's experiment to determine which macromolecule of the bacterial was transformed. They used fractional analysis to isolate RNA, DNA, protiens, lipids and carbohydrates in the heat killed S strain and mixed those with the non-lethal R strain.  Whichever macromolecule killed the mouse was the macromolecule of genetic material.  DNA was the only macromolecule to result in the death of the mouse.  Other studies were performed in the next years to confirm this finding.

For the longest time, blood typing seemed to be a simple area of genetic inheritance from parents.  The individual got one alllele from mom and one allele from dad and their phenotype was formed from there.  Blood type is a codominate trait which is composed of three different alleles O, A and B.  Both A and B are codominant to eachother while O is recessive to both A and B.  Therfore, if an individual has the alleles O and B, they would have a type B blood.  If an individual had the A and B allele, they would have type AB blood.  These alleles determine the type of sugar which is attached to the red blood cells.  Antigens recognize only these types of sugars in the blood as beeing good.  If an individual with type B blood had A sugars in their blood, their body would attack them as foreign.  This is a key concept in blood transfusions between individuals.  If an individual was given a blood type that did not match theirs, they would have a major immunological response.  The Bombay pheonotype puts a wrench in this simple pattern of inheritance.  This is an example of recessive epistasis where if an individual possesses two of the recessive alleles for the bombay gene, they will expressive the bombay phenotype and have type O blood, despite the alleles inherited from their parents.  The Bombay phenotype codes for a substrate which the sugars from the A and B allele bind two.  Without the substrate, the A and B sugars will not bind and they will exhibit type O blood.  With this understanding, no more parents will get blamed for stepping out when they did not.

In humans, the X and Y chromosomes are sex chromosomes of an individual.  The presence of a Y chromosomes often indicates the individual is biologically male (although there can be some variation in this expression).  It is key to note the difference between gender and sex.  Gender is a socially constructed concept about how an individual should be expressing their identiy.  Sex is a biological determination and in no way determines the gender of the individual.  Between the X and Y chromosomes, there are regions known as pseudoausomal regions.  These regions have contain homolgy between the X and the Y chromosome which allow for their pairing during mitosis and meosis and have gotten shorter as time passed.  In the Y chromosom, there are male specic regions (MSY) which is a nonrecombining region.  The sex determining region (SRY) of the Y chromosome controlas main development.  At about 68 weeks in utero, the testes determinign factor is activated on the Y chromosome and testes form in the individual.   The Y chromosome has been largely conserved throughout the evolution of humans therefore it is often used in haplotype studies.  It is found that 10% of the population have gotten their Y chromosome from Ghenghis Khan.

To improve the results of the lab, both the methods of the lab and analysis of the product should be improved on.  First, the reaction turned black indicating something did not react as expected.  This could be due to the rapid heating of the reaction.  As a result, the temperature at which the reaction proceeds should be lowered.  In addition, less sulfuric acid should initially be added to the reaction.  Sulfuric acid is only a catalyst, but it is also a volatile substance.  By starting with two drops instead of four, it allows the reaction to gently start.  After the reaction has proceeded and if there is little water collection, then more sulfuric acid could be added to increase the rate of the reaction.  In addition, a longer reflux time should be utilized to ensure the complete reaction of the reagents.  Finally, during the analysis of the results infrared spectrometry should be done of both starting materials so the final product has something to be compared to.  Both carboxylic acids and alcohols have overlap with the presence of an OH broad band and carboxylic acids and esters are close together.  By doing a comparative analysis on all three compounds, a better supported result can be concluded.  Both these alterations can improve the yield of the experiment and the analysis of the pure product. 

A new study has come out that shows that by the second trimester of pregnancy, long before the baby's eyes can see images, they can detect light. The light-sensitive cells in the developing retina actually communicate with each other as part of an interconnected network. This gives the retina more light-sensititvty and enhances the influence of brain development. Only 3% of the cells that send messages through the optic nerve to the brain in the developing retina are sensitive to light. The other percenatge of cells in the developing retina communicate with other parts of the brain, such as the amygdala.  

Climate change is an extremely important biological topic that must be included in educational curriculums, however it is slow to be included in public schools. It has been debated to push biology courses back a year in high school education, in a specific case study in Concord, Massachusetts, in order to incoorperate a more earth-based class into freshman curriculums. This method of climate change education, I find, is unbenefitial and disabling students from taking more advanced courses in later years of high school careers because they do not have the option early on to skip low level courses. Also, it is completely true the climate change can be incoorperated into ecology units in biology as the earth's ecosystem and weather patterns and climates are vital to the ecological compositions across the world. This would allow a comprehesive lesson on climate change and the effects on organisms and species richness in case studies. Also, this would give the opportunity to take the upper level biology course and learn the same important information about climate change as would be included in an earth science course.