EXAM 4 STUDYGUIDELecture 201. Describe the process of domestication, and how it impacted human life and civilization.a. Early humans were hunter/gatherers and prior to the onset of agriculture, human populations were small. Agriculture began with deliberate planting of seeds and led us to a sedentary lifestyle. As plants became more domesticated, they and humans became increasingly interdependent- for example, cultivated wheat seeds are not easily dispersed in nature so humans must facilitate that. Agriculture also lead to other changes in human behavior and culture such as tool development and animal domestication, eventually leading to increases in human population size. b. Plants produce most of the oxygen we breathe, an assortment of useful chemicals, most of the chemically stored energy we consume as food and burn for fuel. Most plants we encounter on a daily basis were deliberately planted by humans. Also, plants interact extensively with other organisms in the ecosystem.2. Describe artificial selection and its role in domestication.a. As plants were grown and cultivated particular genetic variants were selected based on their specific characteristics. Artificial selection allows humans to breed plants based on which traits we find most appealing for various reasons such as appearance, ease of use, taste, color, etc. Artificial selection is attained by randomly occurring mutations in the plants. 3. Name the location and approximate date of domestication for the eight founder crops.a. Fertile Crescent: soil and environment highly beneficial for crops in the age of early domestication so it was a highly cultivated area. Selection of desirable traits began ~11,000 years ago. Other early regions used- China, Mesoamerica, the Andes, Amazonia, and eastern and north America. All of the 8 founder crops were domesticated in the Fertile Crescent-b. Emmer wheat: 8500 BCEc. Einkorn wheat: 8500 BCEd. Barley: 8500 BCEe. Lentils: 4000 BCEf. Pea: 8500 BCEg. Chickpea: 8500 BCEh. Bitter vetch: 8500 BCEi. Flax: 8500 BCE4. Explain how a few genes can impact multiple traits in a domesticated organism. As examples, describe the molecular mechanisms that impact cultivated corn, tomato, and wheat and how these crops differ from their wild relatives.a. Maize (corn) was domesticated from teosinte which still grows in Mexico and Nicaragua. Teosinte and Maize have the same number of chromosomes and can be crossed to generate a fully fertile hybrid. This is useful in studying basic genetic differences. Maize and teosinte have differences in plant architecture, seed dormancy and plant reproductive structures. These differences are explained by 5 different genetic loci. Maize has increase apical dominance compared to teosinte, which is likely related to the expression of the tb1 gene: tb1 expression levels vary under different environmental conditions—this variability likely basis for selection during domestication of cultivated corn. Tb1 growth regulator generally expressed at low levels in highly branched maize plants and at high levels in plants with one or a few large ears of corn. b. In wheat, cultivated plants are a combo of multiple progenitors. Wild relatives had brittle spikes, selection against shattering so plants retained seed through harvest. When multiple genomes combine, become polyploidy.Polyploidy increases cell size, likely basis for larger grains. There are also differences in protein content that change baking qualities (likely related to few genes’ effects). c. In tomatoes, increased fruit size and palatability were selected for during domestication. Fw2.2 gene is repressedwhich plays a role in fruit size, and cell division increases to produce larger fruit. In wild tomato, allele of fw2.2 that confers selected trait relates to level of expression (amount of product), not to different product functions. 5. Describe examples of selection of developmental features that have led to specific traits in cultivated Brassica species.a. Brassica oleracea cultivars include cabbage, broccoli, cauliflower, kale, brussel sprouts, kohlrabi and turnip. Before cultivation the parent species has swollen root and stem tissues, enlarged axillary buds, and overlapping leaves to surround apical meristem. As an example, cauliflower heads result from flower buds that fail to undergo normal floral development.Lecture 211. Describe several non-food uses of plants and plant related products, including fiber, fuel, plastics, pollution remediation, and medicine.- Plants can produce an amazing assortment of chemicals- Plants provide us with more than food- Plants are sources of novel therapeutic drugs- They provide better fibers for paper or fabric- They are sources of biorenewable products- They provide renewable energy sources- About ¼ of prescriptions written in the US contains at least one product derived from a plant. Some plants are prohibitively expensive to synthesize- Plants can replace petroleum for many products and purposes- Plants can also take up radioactive metals: after 1986 chernobyl nuclear disaster, sunflowers and rape blossoms were used to decontaminate soil in Ukraine. 2. List specific examples of each of the above.- Plants produce hundreds of compounds we use as medicines or drugs- Willow (Salix) bark as a source of aspirin (acetylsalicylic acid)- Foxglove (Digitalis purpurea) as a source of digitalis (treatment for cardiac problems)- Pacific yew (Taxus brevifolia) as a source of taxol (treatment for cancer)- Coffee (Coffea arabica) and tea (Camellia sinensis) as sources of caffeine (stimulant)- Plasmodium causes malaria. It is transferred into humans by infected mosquitoes. Cinchona tree bark contains compound, quinine that kills plasmodium. But plasmodium is developing resistances to quinine so other sources of anti-malarial compounds must be found. - Gin and quinine: British soldiers in tropical regions were given quinine pills to prevent malaria. To disguise its bitter flavor, quinine was mixed with sweet, carbonated water and frequently also with gin- Artemisia annua is a plant with novel antimalarial activities- Wood is primarily composed of plant cell walls- Clothing made from plant fibers (cotton, linin)- Wood is used for building furniture- Plant fibers are used for making paper and before that papyrus- Painting canvas is made from flax or hemp fibers- Poplar is an important source of fiber for paper- Sugars, starches and cellulose can be fermented into ethanol- Biodiesel
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