WARNING: Pictures of the actual pig dissection are shown below.
Dissecting the fetal pig was an incredible and highly educational experience. The dissection was a great opportunity for me to learn and make connections that I would otherwise not understand if I had read information straight from the textbook. This was a very hands-on experience, as I was able to look inside the fetal pig and make direct comparisons between the anatomy and physiology of the pig and human while learning more about the mammalian body and different organ functions.
After prepping for the dissection, one of the first observations my lab group had to make was the sex of the pig. From our observations, we came to the conclusion that the pig was a MALE; the male had a urogenital opening just posterior to the umbilical cord. Throughout the lab and dissection, we observed and dissected the (1) mouth, (2) the digestive system, (3) the respiratory and (4) circulatory systems, (5) the excretory system, and lastly the (6) reproductive system. In the mouth, we observed and located the teeth, tongue, epiglottis, salivary glands, and the opening of the esophagus. In the digestive system, we located the liver, gall bladder, stomach, spleen, small intestine, the pancreas, and the large intestine. In the respiratory and circulatory systems, we located the diaphragm, the esophagus, the trachea, and the heart. In the excretory system, we located the kidneys and the ureter. And lastly in the reproductive system, we located the penis in the male fetal pig.
Two organs that stood out to me the most were the LIVER and the DIAPHRAGM.
Beginning the dissection of the abdominal cavity, I immediately noticed a huge reddish-brown organ—the LIVER. I had no idea how HUGE the liver is; the liver is the largest organ in the abdominal cavity. As I became very puzzled of the gigantic size of the liver, I began to review the functions of the liver (production of bile, conversion of excess glucose into glycogen for storage, regulating blood clotting, etc.). I soon realized that the liver is essential and carries out many functions of the body. Therefore, the size of the liver seems to be reasonable. To learn more about the liver and its functions in the body, check out this link! http://goo.gl/oHlLhu
I was also able to learn more about the DIAPHRAGM and to understand its importance based on the location in the body. The diaphragm separates the digestive organs from the heart and lungs. The diaphragm serves to contract and relaxes during inhalation and exhalation so as to accommodate and expel air from the body. Having learned about the respiratory system and the actual process of breathing, it was amazing to see the organs in front of me. Seeing the organs and their location, I am able to fully understand how the lungs work with the diaphragm to breath.
Overall, it was amazing to look at the fetal pig and realize that my body and the layout of the organs in my body is that like the pig. This gave me great insight into my own body and in mammals in general.
Check out my group’s prezi about our observations of the Kingdom Protista!
DNA Technology: Medical Applications
Check out the newest discoveries of DNA Technology in Medical Applications:)
Mitosis Onion Root Tip Lab
1. Explain how mitosis leads to two daughter cells, each of which is diploid and genetically identical to the original cell. What activities are going on in the cell during interphase?
The process of mitosis and the steps of interphase, prophase, metaphase, anaphase, and telophase, results in the chromosomes and DNA to be duplicated, which are later pulled apart to form two daughter cells. During the first step, interphase, chromosomes’ DNA to duplicate. In prophase, the chromosomes join together by a centromere—forming sister chromatids—and the nuclear membrane and the nucleolus disappear, the chromosomes coil, and the assembly of the spindles occurs. In metaphase, the chromosomes line up on the metaphase plate of the cell and the spindle fibers pull each pair of sister chromatids apart (to opposite poles), in anaphase. During Telophase, the nuclear membrane (cell wall) to form, thus dividing the cell into two daughter cells—DNA was duplicated in the beginning of the cycle and each daughter cell has the same exact DNA.
During Interphase, the cell grows in the G1 phase (increasing cell volume), the cell duplicated its DNA during the S phase, and during the G2 phase, and the cell prepares for mitosis.
2. How does mitosis differ in plants and animals cells? How does plant mitosis accommodate a rigid, inflexible cell wall?
In animal cells, spindle fibers are created by the centrioles, to pull the sister chromatids apart. Unlike animal cells, the plant cells do not have centrioles; therefore the spindle fibers grow on their own. During telophase, animal cells pinch in the middle of cell membrane of the cell (cytoplasm) to form sister cells. Because plant cells have a cell wall and are unable to pinch at the membrane, a cell plate forms between the two poles of the cell and the cell plate divides the cell, creating two sister cells.
Plant mitosis accommodates a rigid, inflexible cell wall by forming the cell plate in order to divide the cell into two daughter cells. Since the cell cannot divide by pinching the cell membrane, the forming of the cell plate is essential.
3. What is the role of the centrosome (the area surrounding the centrioles)? Is it necessary for mitosis?
The centrosome is the area surrounding the centrioles in animal cells (centrioles are not present in plant cells). The centrosome is important during cell division and functions as a microtubule-organizing center. The microtubules then serve to maintain the cell shape and cell movement (chromosome movements in cell division).
Centrosome is essential for mitosis because without the centrosome there would not be an organizing center for microtubules (no production of microtubules) and therefore, there would not be any movement of chromosomes—would not separate and divide. As a result, the cell duplication would not occur and sister cells would not be produced.
1. If your observations had not been restricted to the area of the root tip that is actively dividing, how would your results have been different?
Depending on the region of the onion root that is looked at, under the microscope, the phases seen will be different and will affect the results (the percentage of total cells counted in each phase). The root cap serves to protect the plant and would not show any division of cells (dead cells)–only interphase would be shown. The region of elongation is the area in which the cells are growing (growing longer), but not dividing. Therefore, most of the cells (almost all) would be seen during the stage of interphase. The region of maturation is the region, which cells differentiate themselves and are not growing or dividing. Therefore, a majority of the cells would be seen during interphase.
2. Based on the data table in Table 3.1, what can you infer about the relative length of time an onion root tip cell spends in each stage of cell division?
Based on the data table, the relative length of time an onion root tip cell spends in each stage of cell division are as followed: 1353.60 minutes were spent in interphase, 50.4 minutes were spent in prophase, 11.52 minutes were spent in metaphase, 17.28 minutes were spent in anaphase, and 8.64 minutes were spent in telophase. The data shows that 94% of the cells were counted in interphase and took up 1353 minutes out of 1444 minutes in the total cell cycle time. The prophase, metaphase, and anaphase stages, spent a total amount of 79.2 minutes combined. The telophase stage proved to be the stage that cells were seen spending the least amount of time in, with 8.64 minutes.
In conclusion, cells spent the most amount of time in interphase, due to the duplication of DNA and the preparation of the cell to later divide. This preparation entails, the cell doing work, increasing in size and synthesizing of new proteins and organelles specific for the cell. The phase that spent the least amount of time in the cycle was telophase, due to the fact that telophase is the last stage and is one that is seen less often.
The percentage of cells counted in interphase was unusually high and this number was a signal that a number of errors had occurred during the experiment. Looking to far up the stem, could account for the high percentage of cells in interphase could. The further up the stem, the more cells there are that are in interphase because the cells in the upper region are not dividing. This could explain the high percentage of cells in interphase. Incorrectly identifying interphase from prophase is another error that occurred. Interphase and prophase look very similar through the microscope and those similarities cause misinterpretation of the cells and what phase the cells are in. This could also explain the high percentage of cells in interphase.
3. Pie chart of the onion root tip cell cycle from the data collected in the table above.
Chromatography is important because the process separates mixtures to identify each individual pigment. The molecules (from the mixture) are separated by molecular mass, so all molecules or pigments have a different molecular mass. The mixture is separated and identified by the use of chromatography paper. Chromatography helps to analyze which molecules are in a substance, as the mixture is separated molecularly by the forces of adhesion–solvent and pigments are draw up the chromatography paper due to adhesion and then separated by molecular mass of the solute. The factors that allow chromatography to occur are solubility, adhesion, and mass of solute.
The purpose of the chromatography paper in this experiment is to show the separation of different molecules due to the adhesion of water molecules. The purpose of the solvent is to move the pigments up the chromatography paper through capillary action so that the pigments can be separated. Rf stands for the Retention Factor (a constant). Rf is the movement of pigment relative to the movement of the solvent. This value (constant) is helpful to scientists by allowing scientists to measure each specific Rf value of each pigment, as each pigment has a different Rf value. The Rf value allows scientists to also study what molecules make up each mixture.The D unknown signifies the unknown value of movement of the pigment on the chromatography paper. The D solvent signifies the movement of the solvent (on the chromatography paper).
From the GREEN leaf chromatogram, we were able to identify 2-3 pigments.
From the NON-GREEN leaf chromatogram, we were able to identify 1-2 pigments.
New Fact: I also learned that the red leaves had a darker green pigment than that of the green leaves.
One more Question: Is the rate of photosynthesis different between leaves that are green and leaves that are red?
After researching further about pigments and the absorption of light in photosynthesis, I learned from my prezi presentation (http://goo.gl/hR3qYY) as well as my classmates presentations that plants are green due to chlorophyll a (pigment) in the chloroplast. Chlorophyll a absorbs mostly red and blue light, but reflects green light, the color we see.