protein b – Chemistry – Flashcards
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When amino acids are classified by polarity, what is an example of a nonpolar amino acid? |
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Hydrocarbon alkanes or aromatic |
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What is an example of an acidic amino acid? |
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Has COOH |
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What is an example of a basic amino acid? |
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Amines |
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What is an example of a polar amino acid? |
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Has alcohol |
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What does the net charge on an amino acid depend on? |
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The pH of the solution in which it is dissolved |
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How does an amino acid exist in solution? |
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As a zwitterion |
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Are amino acids polyprotic acids? |
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Yes |
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When a low ph amino acid is added to a base over H3O, which H falls off? |
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The H on the carboxyl end |
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When a zwiterion form amino acid is added to a base over H3O, where does the H fall off? |
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It falls off the amino end |
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What is the pH at which an amino acid has a zero charge? |
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NO pH |
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What charge does a low pH have? |
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Positive |
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At high pH, what is the charge? |
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Negative overall charge |
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What is the isolectric point? pl |
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At intermediate pH the positive charge equals the negative charge-neutral |
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Is the isoelectric point different for each amino acid? |
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Yes |
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What pH and pl is representative of the Zwitterionic form? |
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pH=pl |
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How are polymers of amino acids connected to one another? |
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by peptide bonds |
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What is a dipeptide, tripeptide and polypeptide? |
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Dipeptide-2 amio acid residues joined by a peptide bond, etc |
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Describe a peptide bond? |
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Amide bond between the alpha carboxyl group of one amino acid and the alpha amino group of another- pop water off in the center |
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In the peptide bond, what does the NH3 join? |
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It joins the other side at the carboxyl end, popping off the o- and an H2 from the amino group |
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When are proteins least soluable in water? |
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At their isoelectric points- precipitate from solutions |
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Where is the c terminal amino acid? |
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at the end of the chain having the free coo- group |
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Where is the n terminal amino acid? |
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at the end of the chain having the free NH3+ group |
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What is another name for peptide linkage? |
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Amide linkage representing C=O and NH bond area between the two |
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How are polypeptides classified? |
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Based on the number of AA residues present- Residue is what is left when water is removed |
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What is an oligopeptide |
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12 to 20 residues |
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What is a polypeptide? |
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greater than 20 residues |