Final Review

Final Review - Final Review I Lab 1 Measurement a When...

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Final Review I. Lab 1 Measurement a. When measuring in a graduated cylinder, the measurement is taken from the meniscus II. Lab 2 / 3 Proteins/Starch/Carb test a. Benedict’s Test i. Monosacchrides (glucose/fructose) are reducing sugars, meaning that they possess free aldehide or ketone groups that reduce weak oxidizing agents such as copper in Benedict’s reagent. Benedict’s reagent contains cupric ion complexed with citrate in alkaline solution. Benedicts test identifies reducing sugars based on their ability to reduce the cupric ions to cuprous oxide at basic (high) pH. Cuprous oxide is green to reddish orange. A green solution indicates a small amount of reducing sugars, and reddish orange indicates an abundance of reducing sugars. Nonreducing sugars such as sucrose produce no change in color. b. Iodine Test for Starch i. Starch is coiled polymer of glucose; iodine reacts with these coiled molecules and becomes blueish-black. Iodine does not react with carbohydrates that are not coiled and remains yellowish-brown. A blueish-black color is a positive test for starch, and a yellowish brown color is a negative test for starch. c. Biuret test for Protein i. Proteins are made of amino acids. Peptide bonds form between the amino group of one amino and acid and the carboxyl group of another and is identified by a Biuret test. A cupric ion must complex with four to six peptide bonds to produce a color; individual amino acids do not react positively. Long peptide bonds (like proteins) produce a positive reaction. A violet color is a positive test for the presence of protein; the intensity of color relates to the number of peptide bonds that react.
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III. Lab 4 Microscope anatomy a. Compound Light Microscope (handout diagrams) i. The light source is a lightbulb located at the base of the microscope. The light source illuminates the specimen by oassing light through a thin, almost transparent part of the specimen. The condenser lens, located immediately below the specimen, focuses light from the light source onto the specimen. When the condenser iris diaphragm is open, the image will be bring; when closed the image will be dim. The objectives are three or four lenses mounted on a revolving nosepiece. The most common configuration for student microscopes include four objectives: low (4x), medium (10x), high (40x), and oil immersion (100x). The ocular is the lens that you look through. Microscopes with one ocular are monocular microscopes, and those with two are binocular. Oculars usually magnify the image ten times. The body tube is a metal casing through which light passes to the oculars. The body tube contains mirrors and a prism that redirects light to the oculars. The stage secures the glass slide on which the specimen is mounted. IV.
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Final Review - Final Review I Lab 1 Measurement a When...

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