Biology Lab Exercise 3 Vocabulary

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Exercise 3

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Qualitative Analysis of Biological Molecules

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Qualitative

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Recorded descriptions rather than numerical measurements.

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Quantitative

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Recorded numerical measurements rather than descriptions.

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Carbohydrates

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Molecules that consist of one (monosaccharides), two (disaccharide), or many (polysaccharide) simple sugars. Examples: glucose, sucrose, and starch.

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Benedict's Reagent

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Detects: Sugar
Postive Results: Green, Yellow, Orange, and Brick Red
Negative Results: Blue
Procedure: Add 1 ml of Benedict's and swirl gently. Heat in 95 celsius water for 2 minutes.

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Iodine-Potassium Iodide (IKI)

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Detects: Starch
Postive Results: Black
Negative Results: Yellow
Procedure: Add 1 drop of IKI and swirl gently.

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Hydrolysis

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Many complex organic polymers in the presence of water can be broken down into their simpler monomers by treatment with hydrochloric acid (HCl) and heat. It is a gradual decomposition; that is, a few small monomers are broken off at a time until the polymer is completely converted into monomers.

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Polysaccharides

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Long chain of monosaccharides.

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Oligosaccharides

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A saccharide polymer containing a small number (typically three to ten) of component sugars, also known as simple sugars (monosaccharides).

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Disaccharides

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A double sugar, consisting of two monosaccharides joined by a glycosidic linkage formed during dehydration synthesis.

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Monosaccharides

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The simplest carbohydrate, active alone or serving as a monomer for disaccharides and polysaccharides. Also known as simple sugars, monosaccharides have molecular formulas that are generally some multiple of CH₂O.

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Lipid

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A non-polar organic molecule, which is not soluble in water.

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Triacylglycerols

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Consist of three fatty acids linked to one glycerol molecule.

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Sudan IV

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Detects: Lipid
Postive Results: Orange
Negative Results: No Color
Procedure: Obtain paper disc and mark. Add test substances to paper. Allow paper to dry. Soak paper for 3 minutes in Sudan IV. Remove paper and rinse with water for 1 minute.

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Proteins

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Polymers of amino acids in which the carboxyl group of one amino acid forms a peptide bond with the amine group of another amino acid.

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Biuret Reagent

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Detects: Proteins
Postive Results: Purple
Negative Results: Blue
Procedure: Transfer 1 ml of solution to test tube. Go to fume hood and add 1M NaOH to test tube and swirl gently. Add 10 drops of Biuret reagent to test tube and swirl.

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Primary Structure of a Protein

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The level of protein structure referring to the specific sequence of amino acids.

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Secondary Structure of a Protein

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The localized, repetitive coiling of folding of the polypeptide backbone of a protein due to hydrogen bond formation between constituents of the backbone.

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Tertiary Structure of a Protein

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Irregular contortions of a protein molecule due to interactions of side chains involved in hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges.

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Quaternary Structure of a Protein

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The particular shape of a complex, aggregate protein, defined by the characteristic three-dimensional arrangement of its constituent subunits, each a polypeptide.