The cytoskeleton plays a huge role in the function of an organism and cell. The main function of cytoskeletons is to help maintain the structure of the cell. An important characteristic of cytoskeleton structures is dynamic instability, which allows these structures to polymerize and depolymerize. Some common cytoskeleton structures in the cell include microtubules and actin. Dynamic instability allows these structures to move and help the cell carry out processes like chromosome segregation (microtubules) and muscle contraction (actin). In chromosome segregation, microtubules must be able to become shorter to pull chromosomes apart. It would be difficult for the cell to carry out vital processes and maintain its structure without the help of the cytoskeleton.
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Certain examples would suggest Aristotle’s idea of gravity originating from elements nature to be true, such as dropping an rock and a leaf at the same time. The rock would fall to the ground faster, since it is heavy like the core of the earth. However, Italian scientist Galileo had suspicions about the veracity of this experiment and decided to test it out himself. He experimented by rolling balls of different masses down sloped planes and found that it was possible to have two balls of different masses reach the bottom of the plane at the same time. This discovery suggested that the rate of acceleration to the earth is universal, a novel concept that contradicted Aristotle’s theory of gravity.
Physicist Isaac Newton built off of this idea and made a great leap in the theory, shortly after Galileo’s experimentation. He made a proposition in 1687 that was tremendously successful in predicting the strength of gravity. Isaac believed that the force of gravity that causes a ball thrown into the air to retreat back to the earth was the same force that caused the planets to orbit around the sun. His "Law of Universal Gravitation" states that a particle attracts every other particle in the universe. The degree of this attraction is proportional to the product of their masses and is inversely proportional to the square of the distance between their centers. It is defined by the equation F=(G*m1*m2)/r^2^, where m1 and m2 are the masses of the particles, r is the distance between them, and G is the “gravitational constant." It took another 250 years before this a new theory suggested the Law of Universal Gravitation to be incorrect, due primarily to the fact that this theory works for most practical purposes.
The mechanism controlling the interaction between Populus remuloides (aspen) and Abies laslocarpa (fir) is that of a facilitation relationship. Figure 3 shows that when there is less aspen, fir die significantly more. One reason may be due to fir being able to take over the stands much faster than they would be able to in the normal successional cycle. If fir are taking over faster, and more often then the case of fires is going to occur more. With more fires the cycle will begin again after both species get burnt down. Aspen will then arrive first, and if re-thinned will get taken over by fir again very quickly resulting in more frequent fires and a higher mortality rate for fir. The Aspen morality rate does not increase by a lot because by the time the fire occurs the plot is already overtaken by fir.
Sexual selection is the selection of certain traits based on sexual preference by one of the sexes. This is typically seen as female choice driving the evolution of ornate plumage and elaborate songs used by males during courtship. Sexually selected traits are often very costly for males and can lower survivorship, however they increase fitness. Traits can be costly due to the energy required to have them, or they can attract predators. Brightly colored feathers can be a sexually selected trait that lowers survivorship because it makes the bird more peceptible to preadators. However, colorful wings increases fitness because females are attracted to colorful wings so the male is more likely to attract mates and therefore produce more offspring. In some cases, sexual selection can result in "run-away" sexual selection in which the males evolve very elaborate forms of ornamentation that keep evolving as female preference evolves to prefer more elaborate traits. An example of this is the tail feathers of peacocks. Peacocks that have a larger surface area of eye spots have more young that grow to reproductive age, so the fitness of peacocks increases with the number of eye spots they have on their tails. This provides evidence to support the hypothesis that female peacocks have a sexual preference towards males with many eye spots, indicating high ornamentation increases fitness.
Chronic myelogenous leukemia is a cancer that affects the stem cells of white blood cells and causes them to become over-proliferative. These cancerous white blood cells look as if they properly differentiated, but they are not capable of fulfilling their proper function. Thus, the immune system suffers the consequences since white blood cells play such an important role. If a person with CML is left untreated, they will die in short order. Prior to the 1950s, patients would survive for an average of 2.5 years. Then, Busulfan was introduced to the market and the average life expectancy was increased to about 3.5 years. However, Busulfan was found to kill stem cells and was considered to be very detrimental to the health of the patient. Following the introduction of Busulfan, drug known as Hydroxyurea was created. It further increased the life expectancy to around 4.6 years, but also came with its own side effects. One more drug was introduced before oncologists discovered a drug that worked better than all of the others and had low side effects. This miracle drug was known as gleevec and as of 2011, it increased the survival rate of CML to 95%. Since the introduction of gleevec in 1998, the mortality rate of Chronic myelogenous leukemia has gone down dramatically, providing a ray of hope for those who suffer from the cancer.
Vitamin D is indicated to be lacking in my diet, for the target of 15 micrograms is not met for I only consume about 3 micrograms on average. Not getting enough vitamin D can be dangerous for it plays the role of modulating cell growth, neuromuscular and immune functions, absorption of calcium, therefore, contributing to bone growth. Deficiency not very uncommon because vitamin D is naturally not present in many foods, making it more important that we are aware of our intakes8. Given that we are entering the colder months it also is more challenging to obtain vitamin D from the sun, therefore it must be done by selecting proper foods. As mentioned before, fat-soluble vitamins are more likely to cause toxicity for it is stored in the body, therefore monitoring the intake of this vitamin is extremely important. In most extreme cases toxicity may raise blood levels of calcium, in turn leading to damage to the heart, blood vessels and kidneys8. Some of the best sources of Vitamin D are fatty fish, including salmon and tuna, both of which are foods I enjoy and will add to my diet in greater amounts to make up for the lack of Vitamin D in my diet. Beef liver, cheese, and egg yolks also contain some amounts of vitamin D.
Glycolysis and gluconeogenesis are two glycolytic pathways involving the synthesis and degradation of pyruvate from glucose. Although these reactions look like the opposite of each other, gluconeogenesis actually bypasses three pathways involved in glycolysis. Three irreversible reactions including the enzymes hexokinase, PFK-1, and pyruvate kinase must be bypassed due to their change in free energy. The changes in free energy for these pathways are -33 kJ/mol, -22.2 kJ/mol and -33.2 kJ/mol respectively. When a reaction has a change in free energy that is 0 or close to 0, it is easy to reverse and therefore is used in the process of gluconeogenesis. Being that the changes in free energy for these three pathways in glycolysis have such high negative values, gluconeogenesis must find a way around these reactions in order to degrade pyruvate. Therefore, the reaction uses different enzymes for these three pathways in order to complete the degradation of pyruvate when necessary.
Incandescent lights create the most attraction to insects due to their high emission of light and heat. LED lights have the lowest attraction of insects, yet still attract a wide variety of insects. This is because they do not give off much light or heat (Arthur 2017). Cooler colors of light attract more insects than warmer coolers of light due to the lower frequency of wavelength that is given off. The lower the frequency of wavelength in cooler colored light is easier for insects to detect and therefore is highly attractive. The more insects that are attracted, the more likely a spider will produce a dense web in that relative location in order to increase its likelihood of capturing prey.
According to the CDC, 32 people have been infected with E. coli in 11 states between October 8 and October 31st. “The cases in the U.S and another 18 observed in Canada, indicates that the roman lettuce could be the source of the outbreak”, according to a CDC statement. The authorities informed that a person in California died because of the E. coli bacteria, this is linked to the roman lettuce and what has affected 121 people in 25 states. Now, the symptoms to watch out for because of the Escherichia coli (E. coli) live in the intestines. The majority of E. coli are harmless. However, some are dangerous that can cause severe abdominal cramps, bloody diarrhea, and vomiting. According to Mayo clinic, you can be exposed to E. coli that is in the water or with contaminated foods, especially raw vegetables and meat that is not well cooked.
The first step was to look for patterns among the various species of Setophaga. This included looking at pictures in the Powerpoint that we were presented with, cross referencing those pictures with other images from google images to obtain better views, and study the museum specimens. Afterwards we took note of any specific patterns that were evident in various parts of the bodies of the Setophaga. The patterns were then compiled into a list of ten characteristics that the group felt appropriately depicted the phylogenetic tree given to us at tje beginning of the activity. Once the list was formed, we then went through every picture on the PowerPoint to determine whether or not each species expressed the desired trait. There were instances where the data was collected as a numerical value, with a “1” representing that the trait was present and a “0” representing an absent trait. There were also instances where the traits present had to be identified with colors, adding more variation to the table. Four plumage traits that showed an interesting dispersal among the species were picked from the list of ten characteristics and mapped onto cladograms. The four plumage traits depicted in the cladograms are “breast color”, “throat color”, “homologous nape”, and “wing bar”.