3.3.13.2 Proteins

• The primary structure of a protein is the linear sequence of amino acids.


  True
• Match the protein structure level with its description:

  Primary ↔️ Linear sequence of amino acids

  Secondary ↔️ Local folding (alpha helices, beta sheets)

  Tertiary ↔️ 3D shape of a single polypeptide chain

  Quaternary ↔️ Combination of multiple subunits
• The tertiary structure of a protein is stabilized by interactions like disulfide bridges and hydrophobic interactions.
• Which amino acid is not chiral?

  Glycine
• What type of reaction occurs during peptide bond formation?

  Condensation
• Nonpolar, hydrophobic R-groups are found in amino acids like alanine
• A peptide bond forms between the carboxyl group of one amino acid and the amino group of another, releasing water
• The primary structure of a protein is stabilized by covalent peptide bonds
• Alpha-helices are stabilized by hydrogen bonds between the carbonyl oxygen and the amide hydrogen four amino acids away in the sequence
• Hydrogen bonds stabilize secondary protein structures


  True
• Quaternary structure involves multiple polypeptide subunits


  True
• Nonpolar, hydrophobic amino acids repel water
• Which amino acids are classified as nonpolar and hydrophobic?

  Alanine, Leucine, Valine
• Basic amino acids are positively charged at pH 7.


  True
• What type of bonds stabilize the secondary structure of proteins?

  Hydrogen bonds
• Which bonds stabilize the primary structure of proteins?

  Peptide bonds
• Arrange the levels of protein structure from simplest to most complex:

  1️⃣ Primary

  2️⃣ Secondary

  3️⃣ Tertiary

  4️⃣ Quaternary
• Peptide bonds form when the carboxyl group of one amino acid reacts with the amino group of another.
• The properties of an amino acid are determined by its R-group.
• Basic R-groups are positively charged at pH 7


  True
• The formation of a peptide bond is called condensation


  True
• The primary structure of a protein determines its function


  True
• Beta-sheets can be parallel or antiparallel


  True
• Match the level of protein structure with its description:

  Primary ↔️ Linear sequence of amino acids

  Secondary ↔️ Local folding such as alpha helices

  Tertiary ↔️ 3D shape stabilized by disulfide bridges

  Quaternary ↔️ Combination of multiple subunits
• What are the building blocks of proteins?

  Amino acids
• Which amino acids are negatively charged at pH 7?

  Aspartic acid, Glutamic acid
• Polar, hydrophilic amino acids are capable of attracting water
• What is the process called when a peptide bond forms between amino acids?

  Condensation
• What is the primary structure of a protein defined as?

  Linear sequence of amino acids
• What are the two main types of folding patterns in secondary protein structure?

  Alpha-helices and beta-sheets
• What are the two main stabilizing interactions in tertiary protein structure?

  Disulfide bridges, hydrophobic interactions
• What type of forces stabilize the quaternary structure of a protein?

  Intermolecular forces
• What is the quaternary structure of hemoglobin composed of?

  Four polypeptide subunits
• Proteins are complex polymers of amino acids linked by peptide bonds.
• The overall three-dimensional shape of a protein is referred to as its tertiary structure.
• Secondary structures like alpha helices and beta sheets are stabilized by hydrophobic interactions.

  False
• Match the R-group type with its property:

  Nonpolar, hydrophobic ↔️ Repels water

  Polar, hydrophilic ↔️ Attracts water

  Acidic ↔️ Negatively charged at pH 7

  Basic ↔️ Positively charged at pH 7
• Peptide bonds are covalent bonds that release a water molecule during formation.


  True
• What molecule is released during peptide bond formation?

  Water
• Match the R-group type with its property:

  Acidic ↔️ Negatively charged at pH 7

  Basic ↔️ Positively charged at pH 7

  Nonpolar, hydrophobic ↔️ Repels water

  Polar, hydrophilic ↔️ Attracts water