Drafts

There are three main evolutionary processes that are responsible for evolution. The first one is phyletic evolution, which refers to a gradual change of lineages and relates one specie to another. The second one is speciation, the separation of phyletic lineage into multiple ones. Lastly extinction, the end of a lineage. However, extinction erased relationships among related species because species need other species to connect with otherwise it cannot happen if there is no species left. Species are the fundamental units for classification. There are numerous number of birds species due to different shape, color, habitat, songs and niches. Species are refer to how a single organism can reproduce and creates one or more offspring.

 

Ichthyostega lived at the end of the Late Devonian Period and was was one of the first four-limbed vertebrates in the fossil record. It is an early genus of tetrapodmorph, and although its possession of both limbs and fingers has lead to it often being labeled as a tetrapod, it was more primitive than crown tetrapods and could therefore be more accurately described as a stem tetrapod, or stegocephalian. Whereas crown tetrapods are the group identified as the most recent common ancestor of all living amphibians, the term “stem tetrapods” (tetrapodmorphs) is used for any animal that is more closely related to living amphibians, reptiles, birds, and mammals than to living lungfishes.  Until other finds of early stegocephalians,  Ichthyostega was alone as a transitional fossil between fish and tetrapods. Ichthyostega may have used its tail for swimming, and its forelimbs to move on land. Its forelimbs seem to have been strong enough to pull its body out of the water, and were larger than its hindlimbs. It had a large ribcage with overlapping ribs, which would have limited its ability to make side-to-side motions, and probably moved by dragging itself as its forelimbs did not have the range of rotational motion needed to move in typical quadrupedal gaits.

    In organic chemistry, there is this concept of aromaticity that is very important in determining the stability of a compound. In order to determine if a compound is aromatic, anti-aromatic, or non-aromatic (there is a difference between anti- and non-), the number of pi electrons must be determined. This can be done very simply using 3 simple rules that follow a hierarchy system. This essentially means that out of the three rules, if one rule applies compared to the other, one of the rules will override the other due to it having a higher priority. The three rules are as follows; if a carbon is bonded to a double bond, then it’s counted as 1 pi electron. If the carbon has a lone pair of electrons, it is counted as 2 pi electrons. If the the carbon as a positive charge, then it is counted as 0 pi electrons. The priority of the rules follow the order in which the rules were explained earlier. For example, if a carbon was bonded to a double bond but had a positive charge, that carbon would be counted as 1 pi electron instead of 0. When a compound demonstrates 4n + 2 (n=number of pi electrons) pi electrons, then the compound is aromatic. If the compound is antiaromatic, it will exhibit 4n pi electrons. Any other number of pi electrons means that the compound is non-aromatic. In terms of stability, aromatic compounds are the most stable, non-aromatic compounds are the second most, and antiaromatic compounds are the least stable.

The Gorgonopsia (“Gorgon faces”) are an extinct suborder of a group of therapsids called theriodonts, which are a group of therapsids. The gorgonopsians evolved from a reptile-like therapsid in the Middle Permian, and although early gorgonopsids were no larger than a dog, later gorgonopsids were some of the largest carnivores of the Late Permian period. They have mammalian specializations that include having teeth of different shapes (heterodonty), having a fully developed temporal fenestra, a vaulted palate, and early ear bones. They possibly had a combination of scales and bristles, and they are assumed to have been terrestrial. The Gorgonopsia were the only theriodont line that went extinct during the Permian-Triassic mass extinction event.

Despite some of the positive findings in this study there were a few important gaps. There were no control subjects to compare the DPN subjects to (no non-diabetic subjects or diabetic subjects without DPN). Therefore it was not a randomized study and there was no placebo. The participants were all older individuals with a wide range of a duration of diabetes (12.2 years). They also did not define what stage of neuropathy the patients were experiencing. Also, there was no specific regimen on what equipment was used for exercise training. Although it was a supervised exercise intervention, the subjects were allowed to choose from a variety of options and were only encourages to utilize different equipment. Nerve conduction study was used to test conduction velocity, motor action potential, and amplitude but not significant changes were found. Lastly, skin biopsies were used to test intraepidermal nerve fiber density and epidermal axon branching. There was only a significant difference in nerve fiber branching at the proximal biopsy site.

Recrystallization is a process used in chemistry laboratories to purify organic compounds that are solids at room temperature. The identity of a compound can be found using recrystallization methods in conjunction with other procedures. In organic chemistry lab, an unknown compound was given to recrystallize and identify. In order to start with the recrystallization process, one had to first decide the preferred solvent to dissolve the unknown compound. Five different solvents were available ,water, methanol, pure ethanol, hexane and toluene, to test for the most effective solvent for the unknown. Once determined, the student boiled the solvent on a hot plate and slowly added drops to the premeasured erlenmeyer flask containing about 250 mg of the unknown. Soon after, the student placed the dissolved solution on the bench to cool and then into an ice bath to allow crystal formation. The following steps included using a suction filtration to remove as much liquid as possible and then scrape crystals onto a filter paper to weigh. In addition to recrystallizing the unknown, the student measured its melting point, which is another physical property used for compound identification. Performing recrystallization in combination with finding the melting point, will lead to the identification of an organic compound.

          The article “A Complete Skull from Dmanisi, Georgia, and the Evolution of Early Homo” describes archaeological finds from a site in central Asia and their relevance to early hominin evolution and migration. Excavation began on the Dmanisi site in 1999, with researchers first finding assorted fauna fossils, then stone tools, and finally hominid remains. These hominid fossils have been linked to H. habilis and H. erectus in Africa and H. erectus in East Asia. The hominid remains in Dmanisi are especially important because they have been dated to 1.8 million years ago, and thus represent the earliest hominid finds outside of Africa, casting doubt on previous assumptions as to when human ancestors first travelled to other continents. One of the main focuses of the article is a particular fossil known as skull 5, which is the first and only completely preserved adult hominid skull found from the early Pleistocene. This fossil is important because it provides evidence of the orientation of the face relative to the brain case, and serves as an intact sample of fully developed adult cranial morphology, which was previously unavailable due to earlier finds being either incomplete, damaged, or juvenile skulls. Skull 5 is described as having small brain case, a large, prognathic face, and very robust features. Skull 5 in the context of the 4 other sets of remains, also shows distinct morphologic variations, despite almost certainly being of the same species, since they were all found in the same general location and dated to approximately the same time. The notable anatomical differences in the shape of the skulls led researchers to measure the morphological variation between the Dmanisi finds and compare it to the variation found in extant ape species, like chimpanzees and bonobos. This analysis led them to conclude that the variation in the Dmanisi fossils is well within the range of normal variation within a species population. The article went on to say that such a conclusion raises questions about whether previous finds from elsewhere in Asia and Africa, which were categorized as separate and distinct species, are in fact merely part of a single widespread Homo lineage.