lec1 Amino acids

• How many amino acids are there in total?

  There are 20 amino acids.
• How can aromatic amino acids be used in protein concentration estimation?

  Aromatic amino acids can be used to estimate protein concentration by measuring absorbance at specific wavelengths of UV light.
• What specific wavelength of UV light is used for measuring aromatic compounds?

  The specific wavelength is 280 nm.
• What technique can be used to find the absorbance of light at 280 nm?

  UV Spectrophotometry can be used to find the absorbance of light at 280 nm.
• What does absorbance correlate to according to the Beer Lambert Law?

  Absorbance correlates to concentration according to the Beer Lambert Law.
• How can protein concentration be calculated if the amino acid composition is known?

  Protein concentration can be calculated based on the ratio of aromatic amino acids to non-aromatic residues.
• What is the Beer Lambert Law used for?

  The Beer Lambert Law is used to relate absorbance to concentration in solutions.
• What is a zwitterion?

  A zwitterion is a molecule with functional groups that have both positive and negative charges, resulting in a net charge of zero.
• What is an isoelectric point (pI)?

  The isoelectric point (pI) is the pH at which a particular molecule has no net charge.
• Why is the isoelectric point important?

  The isoelectric point determines the chemical properties of amino acids at physiological pH.
• How do aspartic acid and arginine behave at physiological pH?

  Aspartic acid is negatively charged, while arginine is positively charged at physiological pH.
• What is a chiral stereoisomer?

  A chiral stereoisomer is a compound with the same molecular formula but a different arrangement of atoms in space.
• What is the difference between D and L amino acids?

  D and L amino acids are chiral stereoisomers that are non-superimposable mirror images of one another.
• Which type of amino acids are naturally occurring in nature?

  L amino acids are naturally occurring in nature.
• How are amino acids classified as D or L?

  Amino acids are classified as D or L using glyceraldehyde as a reference, based on the orientation of the -OH group on the chiral carbon.
• In L glyceraldehyde, where does the -OH group point?

  In L glyceraldehyde, the -OH group points left on the chiral carbon.
• How is the configuration of amino acids determined in a Fischer projection?

  The configuration is determined by arranging the molecule with the carboxyl group at the top and the R group at the bottom.
• How is a D-amino acid characterized in terms of the amino group?

  A D-amino acid has the amino group on the right in a Fischer projection.
• How is an L-amino acid characterized in terms of the amino group?

  An L-amino acid has the amino group on the left in a Fischer projection.
• What naming system is used to represent amino acids?

  The R and S naming system is used to represent amino acids.
• What is the configuration of most naturally occurring amino acids?

  Most naturally occurring amino acids are in the S configuration, except for L-cysteine.
• What is optical rotation in chiral molecules?

  Optical rotation is the characteristic specific rotation of every chiral molecule that can be measured by a polarimeter.
• What does it mean if an amino acid rotates plane polarized light clockwise?

  If an amino acid rotates plane polarized light clockwise, it is dextrorotatory or (+).
• What does it mean if an amino acid rotates plane polarized light anticlockwise?

  If an amino acid rotates plane polarized light anticlockwise, it is levorotatory or (-).