Proteins

• What elements do proteins always contain in addition to carbon, hydrogen, and oxygen?

  Nitrogen
• What are the monomers that make up proteins called?

  Amino acids
• How many different amino acids are used to make up proteins?

  About 20 different amino acids
• What determines the shape of a protein?

  The specific sequence of amino acids in the chain
• What is the general structure of an amino acid?

  • Central carbon atom
  • Amino group (-NH2) at the N-terminal
  • Carboxyl group (-COOH) at the C-terminal
  • Hydrogen atom
  • R group (varies in each amino acid)
• What happens to the amino group of an amino acid at pH 7?

  It gains an H and becomes positively charged
• What is a zwitterion?

  An ion that has both a positive and a negative charge
• What additional element do proteins contain that carbohydrates and lipids do not?

  Nitrogen
• What are proteins made of?


  Proteins are made of monomers called amino acids.
• What are the chains of amino acids in proteins called?

  Polypeptides
• How many different amino acids are used to make up proteins?


  About 20 different amino acids
• What determines the shape of a protein?

  • The specific sequence of amino acids in the chain
  • The arrangement of polypeptides
  • The interactions between different amino acids
• What is the basic structure of all amino acids?


  All amino acids have a central carbon atom, an amino group, a carboxyl group, a hydrogen atom, and an R group.
• What is the N-terminal of an amino acid?


  The N-terminal is the end of the molecule with the amino group, -NH2.
• What is the C-terminal of an amino acid?


  The C-terminal is the end of the molecule with the carboxyl group, -COOH.
• What is the R group in an amino acid?


  The R group is the variable group that differs in each amino acid.
• What role does sulfur play in proteins?


  Many proteins contain sulfur as part of their structure.
• What is the significance of the sequence of amino acids in a protein?


  The sequence determines the protein's shape and function.
• What is the basic structure of all amino acids?


  All amino acids have a central carbon atom, an amino group, a carboxyl group, a hydrogen atom, and an R group.
• What is the N-terminal of an amino acid?


  The N-terminal is the end of the molecule with the amino group, -NH2.
• What is the C-terminal of an amino acid?


  The C-terminal is the end of the molecule with the carboxyl group, -COOH.
• What happens to the amino group of an amino acid at pH 7?


  At pH 7, the amino group gains an H and becomes positively charged.
• What happens to the carboxyl group of an amino acid at pH 7?


  At pH 7, the carboxyl group loses an H and becomes negatively charged.
• What is a zwitterion?


  A zwitterion is an ion that has both a positive and a negative charge at the same time.
• At what pH does an amino acid exist as a zwitterion?


  An amino acid exists as a zwitterion at pH 7.
• What are the components attached to the central carbon atom of an amino acid?

  • An amino group (-NH2)
  • A carboxyl group (-COOH)
  • A hydrogen atom
  • An R group (which varies among amino acids)
• What are proteins made of?


  Linear sequences of amino acids
• What happens during the formation of a peptide bond?


  The amino group of one amino acid reacts with the carboxyl group of another, eliminating water
• What is the result of the condensation reaction that forms a peptide bond?


  A dipeptide is formed
• How can a dipeptide be represented chemically?


  As NH2.CHR1.CO-NH.CHR2.COOH
• What is the significance of the order of amino acids in a dipeptide?


  Different orders of amino acids result in different dipeptides with different properties
• What is the process of peptide bond formation?


  • The amino group of one amino acid reacts with the carboxyl group of another
  • Water is eliminated in this condensation reaction
  • A peptide bond is formed, resulting in a dipeptide
• How do the properties of dipeptides differ based on amino acid order?


  • Different sequences of amino acids yield different dipeptides
  • Each dipeptide has unique chemical and physical properties
• What is a peptide bond?


  The chemical bond formed by a condensation reaction between an amino group and a carboxyl group.
• How is a peptide bond formed?


  It is formed by a condensation reaction between the amino group of one amino acid and the carboxyl group of another.
• What should you refer to when discussing the bond between amino acids?

  You should refer to a 'peptide' bond, not a 'dipeptide' bond.
• What is the difference between a peptide bond and a dipeptide bond?


  • A peptide bond is the bond between two amino acids.
  • A dipeptide bond refers specifically to the molecule formed by two amino acids linked by a peptide bond.
• What is the primary structure of a protein?


  The order of the amino acids in a polypeptide chain
• How many different types of amino acids can be found in polypeptides?


  Up to 20 different types
• What determines the primary structure of a protein?


  The base sequence on one strand of the DNA molecule