Botana curus is a valuable plant because it produces Curol, a compound used for treating certain kinds of cancer. Curol cannot be produced in the laboratory. Botana Curus grows very slowly and is on the endangered species list, so its ability to provide Curol in large quantities is limited. Species that are more closely related to Botana curus are more likely to produce the important substance Curol. Three similar plant species that are plentiful (X, Y, and Z) may be related to Botana curus.
You will work as a researcher to: * Gather structural and molecular evidence to determine which plant species is most closely related to the hypothetical species. Botana curus. * Use this evidence to decide which plant species is most likely to serve as a source of the important substance Curol. Safety * You will need to wear goggles while conducting Test 4 and 5. * Do not eat or drink anything in the laboratory while doing this laboratory activity. Important Note: Record all of your data and answer on these laboratory sheets.
You will need to keep them for review before the Regents Examination.
Later, you will need to transfer your answers to separate Student Answers Packet. Your teacher will use the packet in grading your work, and the school will retain it as evidence of your completion of the laboratory requirements for the Living Environment Regents Examination. Structural Evidence for Relationships Perform the following test and record your observations in Table 1 on page 8 of this packet. Use a hand lens or microscope as needed. Test 1—Structural characteristics of plants a. Do not remove the plant samples from the plastic bags/cards. b. Compare the structural characteristics of the lant samples.
Record your observations in Table 1 (see page 8). Test 2—Structural Characteristics of seeds a. Do not remove the seed samples from the plastic bags/cards. b. Compare the structural characteristics of the seed samples. Record your observations in Table 1 Test 3—Microscopic Internal Structure of stems. a. Use the lowest magnification on your microscope to examine the slides that show cross sections through stems of Botana curus and Species X, Y, and Z. Compare the arrangement (circular or scattered) of the bundles of conducting tissue in the speciments. Refer to figure 1. b.
Record your observations (using words and /or diagrams) of the conducting tissue arrangements in Table 1. Hypothesize: Test 1-3 a. Based on your data for structural relationships, which species (X, Y, or Z) would you hypothesize is most likely to produce Curol? b. Explain how the evidence from your data table supports your hypothesis. You wil test your hypothesis by completing additional test in the second part of this laboratory activity. Molecular Evidence for Relationships Test 4—Paper Chromatography to Separate Plant Pigments a. You must wear safety goggles when performing this part of the activity. b.
Draw a pencil line 2cm from the bottom of the chromatography paper Bc (Botana curus), X, Y, and Z as shown in figure 1. c. Use a clean microtip dropper to transfer two drops of plant extract from Botana curus just above the pencil line as shown in Figure 1. d. Using a clean dropper each time, repeat the procedure to place drops of the other plant extracts in the appropriated locations on the paper. e. Add just enough water to cover the bottom of the cup approximately 1 cm deep. The water line should NOT be high enough to touch the spots of plant extract on the chromatography paper when the paper is placed in the cup. . Fold the chromatography paper and stand it in the cup as shown in Figure 2. g. The chromatography paper must be removed from the cup before the water line reaches the pencil labels at the top of the chromatography paper. While the plant extracts are moving up the chromatography paper, go on to test 5, but keep checking on the progress of the water moving up the paper so that you can removed it at the roper time. h. Once the chromatography is done, record your observations of the colors and relative amounts of pigments in Table 1. i. Clean the microtip droppers thoroughly by rinsing them with water.
Carefully our solutions from the chromatography cup into the waste container. Discard the used chromatography paper. Test 5—Indicator Test for Enzyme M a. You must wear safety goggles when perform this part of the activity. b. It is not practical to test a plant directly for Curol. However, if enzyme M is present, a plant may produce Curol. Test the plant extracts from Botana curus for the presence of enzyme M. Put one small scoop of indicator powder into one depression of the well tray. Use a clean microtip dropper to add 5 drops of Botana curus extract to the indicator powder. A fizzing reaction indicates that enzyme M is present. . Repeat the test for enzyme M using the other plant extracts. e. Record the results of your tests for enzyme M in Table 1. f.
Clean the microtip droppers thoroughly by rinsing them with water. Rinse the well tray and blot it dry using a paper towel. Reminder: Complete the chromatography tests and observations before going on. Test 6-Using Simulated Gel Electrophoresis To CompareDNA a. For this test, you will use the plastic bags containing colored paper strips representing portions of DNA molecules. The letters on these strips represent the sequence of bases in DNA molecules isolated from Botana curus and Species X, Y, and Z. . To compare DNA molecules, scientists use enzymes that bind to and cut specific base sequences within the DNA. Imagine that you are using an enzyme that binds to the base sequence CCGG and cuts between the C and G. Simulate this cutting process as follows: bi. Remove one of the colored paper strips from the plastic bag labeled Botana curus. Locate and lightly shade all CCGG sequences on the DNA from Botana curus. The shaded areas represent where the enzyme would bind to cut the DNA. b2. Use scissors to cut off all the “white space” above and below the string of letters representing the DNA bases.
Also remove the white paper to the left and right of the string of letters. (This will enable them to fit better in the spaces provided in Table 2 on page 9. ) b3. Now cut the strip between the C and G within each of the shaded enzyme recognition sites. This will result in several fragments of DNA. c. Scientists use gel electrophoresis to separate the DNA fragments resulting from this binding and cutting process. In an electrical field, the negatively charged DNA molecules migrate through a gel-like material toward the positively charged pole.
The smaller molecules migrate more rapidly through the gel than the larger ones do. d. Simulate the electrophoresis process by placing the DNA fragments from Botana Gurusin the appropriate well on the Simulated Electrophoresis Gel (Table 2). Simulate the effect of electrical current on the DNA fragments by counting the number of letters (bases) in each of the fragments and moving them to the appropriate location on the electrophoresis gel. Refer to the number of DNA letters indicated along the left side of the gel to detennine the final position for each fragment. e.
Call your teacher over to check your work for Botana Gurusbefore you continue with the DNA from the other species. f. Mark a horizontal line to indicate the final position of each fragment of Botana GurusDNA on the simulated electrophoresis gel (Table 2), then record the size on the fragments (number of bases in each) in Table 1. g. Repeat this process for each of the other species (X, Y, and Z); lightly shade the CCGG sequences, cut the DNA, and separate the resulting fragments. h. Mark the final position of the DNA bands for each species on the gel (Table 2), then record the size of the fragments (number of bases in each) in Table 1. . Discard the used paper DNA fragments and return all other materials to their original location. Test 7-Translating the DNA Code ToMake a Protein a. The sequences of DNA bases below represent parts of the genes responsible for the production of one type of protein, an enzyme, produced by Botana Gurusand Species X, Y, and Z. b. Under each DNA sequence, write the complementary messenger RNA base sequences that each of these gene fragments would produce. Note: Unlike during DNA replication, in the production of messenger RNA, the DNA base “A” specifies the RNA base “U. ” c.
Use the universal genetic code table your teacher provides to translate the messenger RNA base sequences into sequences of amino acids in the protein produced by each species. Write the sequences of amino acids under the messenger RNA sequences. Botana curus CAC GTG GAC TGA GGA CTC CTC Sequence of bases in mRNA produced Sequence of amino acids in the protein Species X CAC GTG GAC AGA GGA CAC CTC Sequence of bases in mRNA produced Sequence of amino acids in the protein Species Y CAC GTG GAC AGA GGA CAC CTC Sequence of bases in mRNA produced Sequence of amino acids in the protein Species Z CAC GTA GAC TGA GGA CTT CTC
Plant and animal species are being lost at a rate that is unprecedented in the history of life. Human activities are responsible for much of this biodiversity crisis. Some biologists estimate that within the next century, half of Earth’s current species may become extinct. Extinction and the loss of biodiversity occurs when species do not have adaptations that enable them to survive environmental changes. Human activities such as destruction of natural habitats and pollution are thought to be the major environmentalfactors causing the decline of species, but others are also important.
Overhunting, introduction of foreign species that compete with native species, and removal of predators have also played,a significant role in endangering some species. Why should we worry aboutthe loss of biodiversity? We depend on many speciesfor food, clothing,shelter,oxygen,soil fertility-the list goes on and on. Large-scaleextinctionsof other species may be a warningto us that we are altering the biosphereso rapidlythat our species is threatenedtoo. Biodiversity ensures the availability of a rich variety of genetic material that may lead to future agricultural or medical discoveries having significant value to humankind.
Some species have been used as sources for medicines and other useful products. Scientists now use genetic engineering to transfer desirable genes from one species to another. As diversity is lost, potential sources of these genetic materials may be lost with it. Biodiversity also increases the stability of the ecosystem. Every population is linked, directly or indirectly, with many others io an ecosystem. Disruptions in the numbers and types of one species can upset ecosystem stability. This means that extinction of one species can accelerate the rate of extinction for other species.
Endangered species hold medicinal, agricultural, ecological, commercial, and aesthetic value. They must be protected so that future generations can experience their presence and value. Assume that the plant you identified as being closely related to Botana Gurusgrows rapidly, survives in many environments, and produces’Curo!. News reports indicate that Botana Gurusplants may become extinct unless expensive efforts are made to preserve the species. Members of your research team disagree as to whether or not Botana Gurusshould be saved.
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