L1 biochem Amino Acids and pKa Concepts
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Questions and Answers

How many amino acids can humans produce on their own?

  • 18
  • 11 (correct)
  • 20
  • 9

    • What is the total number of essential amino acids that humans need to obtain from food?

  • 11
  • 18
  • 20
  • 9 (correct)

    • Which of the following correctly describes the role of dietary sources in amino acid supply?

  • Only 9 amino acids are needed from dietary sources. (correct)
  • Humans do not require any dietary amino acids.
  • All amino acids can be synthesized internally.
  • Humans can produce all essential amino acids through metabolism.

    • Which statement about amino acids is true?

    <p>Some amino acids are essential, while others are non-essential.</p> Signup and view all the answers

    Why are the nine amino acids important for humans?

    <p>They must be obtained through dietary sources.</p> Signup and view all the answers

    In acidic conditions, what is the predominant charge of mammalian amino acids?

    <p>Positive</p> Signup and view all the answers

    Which configuration is unique to all mammalian amino acids?

    <p>L-configuration</p> Signup and view all the answers

    At physiological pH, mammalian amino acids usually exist as which form?

    <p>Zwitterionic</p> Signup and view all the answers

    In a solution with a low pH, amino acids will predominantly act as which type of ion?

    <p>Cation</p> Signup and view all the answers

    What happens to the charge of mammalian amino acids when the pH of the solution increases?

    <p>Decreases positive charge</p> Signup and view all the answers

    What does a high pKa value indicate about an acid's strength?

    <p>The acid is weak and dissociates minimally.</p> Signup and view all the answers

    At what situation do the groups start donating hydrogen instead of the medium?

    <p>When pH equals pK.</p> Signup and view all the answers

    Which pKa value corresponds to the α-carboxylic group in glycine?

    <p>2.2</p> Signup and view all the answers

    What does PI represent in the titration curve of glycine?

    <p>The pH at which the zwitterion has a net charge of zero.</p> Signup and view all the answers

    When a molecule is 100% in zwitterion form, what is true about its charge?

    <p>It has no net charge.</p> Signup and view all the answers

    Which amino acid is classified as a derivative amino acid?

    <p>Histidine</p> Signup and view all the answers

    Which amino acid is not typically categorized as a derivative amino acid?

    <p>Glutamine</p> Signup and view all the answers

    Which of the following amino acids has a side chain that can create a positively charged group at physiological pH?

    <p>Histidine</p> Signup and view all the answers

    Which amino acid is the simplest in structure and does not contain an R group that can be classified as a derivative?

    <p>Glycine</p> Signup and view all the answers

    Which derivative amino acid is essential for the synthesis of neurotransmitters?

    <p>Histidine</p> Signup and view all the answers

    Which amino acid is known as an essential amino acid that must be obtained from dietary sources?

    <p>Leucine</p> Signup and view all the answers

    Which amino acid is a non-essential amino acid that the body can synthesize?

    <p>Alanine</p> Signup and view all the answers

    What is the function of histamine in the body?

    <p>Acts as a neurotransmitter</p> Signup and view all the answers

    Which of the following amino acids is considered a sulfur-containing amino acid?

    <p>Cysteine</p> Signup and view all the answers

    What characteristic is common to all standard amino acids?

    <p>They all contain a carboxyl group.</p> Signup and view all the answers

    Study Notes

    Amino Acids Overview

    • Humans can produce 11 amino acids; 9 essential amino acids must be obtained from food.
    • Amino acids are characterized by their basic structure, containing an α-amino group and an α-carboxylic group.

    pKa Concept

    • pKa (acid dissociation constant) measures an acid's ability to donate protons.
    • High pKa indicates low acidity and low concentration of protons.
    • pKa values for amino acid groups:
      • α-amino group: 9.4
      • α-carboxylic group: 2.2

    Titration Curve of Glycine

    • Titration curve demonstrates the relationship between the pH of a solution and the ionization of glycine.
    • Key points on the curve:
      • pK1: pH at which 50% of molecules are in cation form and 50% are in zwitterion form.
      • pI: point where net charge of the molecule is zero.
      • pK2: pH at which 50% of molecules are in anion form and 50% are in zwitterion form.
    • Glycine, like all mammalian amino acids, exists primarily in L-configuration.

    Acidic Medium Behavior

    • In an acidic medium, amino acids are likely to exist as cations.

    Buffering Action

    • Buffering action is especially significant with specific amino acids, notably histidine.

    Derivative Amino Acids

    • Histamine is an example of a derivative amino acid.

    Structural Characteristics

    • The general structure of amino acids is distinguished by their unique side chains (R groups), which determine their properties and classification.

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    Amino Acids PDF

    Description

    This quiz covers the basics of amino acids, including their structure and the essential amino acids necessary for human health. It also explores the pKa concept and the titration curve of glycine, illustrating how these elements relate to acid-base chemistry. Test your understanding of these fundamental biochemical topics!

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