Catalase Lab essays

Catalase Lab essays The two purposes of this experiment were to see the effect of enzyme concentration on enzyme activity and to see the effect of temperature on enzyme activity. Enzymes are the most important part of living cells. Cells cant work or carry out there jobs without them. Enzymes act like catalysts in living cells. Catalysts speed up chemical reactions but remain unchanged by it. Enzymes are made of protein. Enzymes are sometimes called enzyme catalysts. There is a specific enzyme for every chemical reaction in the body. The chemicals that enzymes react in are called substrates. An enzyme performs its effect by combining temporarily with its substrate. As a result, a substrate becomes more reactive. The rate of the formation of products increases. Catalase is present in most cells and high concentrations are found in liver and blood cells. Hydrogen peroxide is formed as a by-product of cellular respiration in cells but water is the most common one. Hydrogen peroxide is toxic and would kill cells if it were not immediately broken down or removed. So toxic accumulation does not happen, catalase breaks down hydrogen peroxide into water and oxygen. This reaction is very fast. Each catalase is capable of converting 5,000,000 molecules of hydrogen peroxide per minute at 0Â ° C. I predict that the increase in temperature will effect the enzyme activity by making it higher because our bodies function better at a high temperature so it makes sense that the enzymes that are in us would. I f my prediction is correct, I will have proved that enzyme activity is higher at higher temperatures. I also predict that more concentration of enzymes will result in higher enzyme activity. If my predictions are correct, I will have proved that enzyme activity is higher with higher enzyme concentration. See lab handout entitled Investigating the Enzyme, Catalase. ...

Guil Naquitz (Mexico) - Key Evidence of Maize Domestication History

Guil Naquitz (Mexico) - Key Evidence of Maize Domestication History Guil Naquitz is one of the most important archaeological sites in the Americas, recognized for its breakthrough discoveries in understanding plant domestication. The site was excavated in the 1970s by KV Flannery, using then-new methods of environmental and ecological sampling, and the results of those sampling techniques and other excavations that followed rewrote what archaeologists had previously understood of the timing of plant domestication. Guil Naquitz is a small cave  occupied at least six times between 8000 and 6500 BC, by hunters and gatherers, probably during the fall (October to December) of the year. The cave is in the Tehuacn valley of the state of Oaxaca, Mexico, about 5 kilometers (3 miles) northwest of the town of Mitla. The mouth of the cave opens near the base of a large ignimbrite cliff rising ~300 meters (~1000 feet) above the valley floor. Chronology and Stratigraphy Five natural strata (A-E) were identified in the cave deposits, which extended to a maximum depth of 140 centimeters (55 inches). Unfortunately, only the top strata (A) can be conclusively dated, based on radiocarbon dates from its living floors and pottery which matches Monte Alban IIIB-IV, ca. 700 AD. The dates of the other strata within the cave are to an extent contradictory: but AMS radiocarbon dates on the plant parts discovered within layers B, C, and D have returned dates to nearly 10,000 years ago, well within the Archaic period and, for the time it was discovered, mind-blowingly early. Considerable and heated debate occurred in the 1970s, particularly about the radiocarbon dates from Guila Naquitzs teosinte (precursor to maize) cob fragments, concerns which largely dissipated after similarly old dates for maize were recovered from the San Marcos and Coxcatlan caves in Oaxaca and Puebla, and the Xihuatoxtla site in Guerrero. Macro and Micro Plant Evidence A wide range of plant food was recovered within the cave deposits of Guil Naquitz, including acorns, pinyon, cactus fruits, hackberries, mesquite pods, and most importantly, the wild forms of bottle gourd, squash and beans. Other plants attested at Guila Naquitz chili peppers, amaranth, chenopodium, and agave. This evidence includes plant partspeduncles, seeds, fruits, and rind fragments, but also pollen and phytoliths. Three cobs with plant elements of both  teosinte (the wild progenitor of  maize)  and maize, were found within the deposits and direct-dated by AMS radiocarbon dating to about 5400 years old; they show some signs of domestication. Squash rinds were also radiocarbon dated: they returned dates of approximately 10,000 years ago. Sources This article is a part of the About.com guide to the American Archaic, and the Dictionary of Archaeology. Benz BF. 2001. Archaeological evidence of teosinte domestication from Guil Naquitz, Oaxaca. Proceedings of the National Academy of Sciences 98(4):2105-2106. Crawford GW. 2015. Food Production, Origins of. In: Wright JD, editor. International Encyclopedia of the Social Behavioral Sciences (Second Edition). Oxford: Elsevier. p 300-306. Flannery KV. 1986. Guila Naquitz: Archaic Foraging and Early Agriculture in Oaxaca, Mexico. New York: Academic Press. Marcus J, and Flannery KV. 2004. The coevolution of ritual and society: New 14C dates from ancient Mexico. Proceedings of the National Academy of Sciences 101(52):18257–18261. Piperno DR. 2003. A few kernels short of a cob: on the Staller and Thompson late entry scenario for the introduction of maize into northern South America. Journal of Archaeological Science 30(7):831-836. Schoenwetter J. 1974. Pollen Records of Guila Naquitz Cave. American Antiquity 39(2):292-303. Smith BD. 1997. The Initial Domestication of Cucurbita pepo in the Americas 10,000 Years Ago. Science 276(5314):932-934. Warinner C, Garcia NR, and Tuross N. 2013. Maize, beans and the floral isotopic diversity of highland Oaxaca, Mexico. Journal of Archaeological Science 40(2):868-873.