Proteins

    Cards (17)

    • How many amino acids are there
      20
    • What differs between each of the 20 amino acids
      The R group
    • How can amino acids bond together
      By forming a peptide bond
    • Dipeptide
      2 amino acids bonded together
    • Polypeptide
      3 or more amino acids bonded together
    • How does a polypeptide become a protein
      It folds into a complex 3D shape to be classified as a protein molecule
    • Name the 4 levels of protein structure
      1. Primary structure
      2. Secondary structure
      3. Tertiary structure
      4. Quaternary structure
    • Describe the primary structure
      The specific sequence of amino acids in a polypeptide chain joined by peptide bonds
    • Describe the secondary structure
      The oxygen atoms in the C--O groups have a small negative charge and the hydrogen atoms in the N-H groups have a small positive charge. The opposite charges attract and hydrogen bonds form. The hydrogen bonds cause the polypeptide chain to fold into alpha helixes or beta pleated sheets
    • Describe tertiary structure
      The overall 3D shape of a polypeptide chain
    • Describe quaternary structure
      Some proteins consist of multiple polypeptide chains working together as a large molecule (subunits). Quaternary structure shows how the individual subunits are arranged to form a 3D structure. Some proteins are also made up of non-protein molecules (prosthetic groups). Quaternary structure shows the position of prosthetic groups.
    • What are proteins with prosthetic groups called
      Conjugated proteins
    • Name the 4 bonds that can form between the R groups
      1. Hydrogen bonding
      2. Ionic bonds
      3. Disulfide bridges
    • Describe hydrogen bonding
      A hydrogen bond forms when there are weak positive and negative bonds between the R groups. Hydrogen bonds are weak- they can be broken by high temperatures or changes in pH
    • Describe hydrophobic and hydrophilic interactions
      Amino acids with hydrophobic R groups tend to cluster together and are usually found in the centre of proteins to avoid water. Amino acids with hydrophilic R groups are usually found at the surface of proteins to interact with water molecules
    • Describe ionic bonds
      Forms between amino acids with charged R groups. The opposite charges attract to make an ionic bond. Ionic bonds are broken by changes in pH
    • Describe disulfide bonds
      Happens when the R group in the amino acids contain a sulfur atom. The two sulfur atoms form a covalent bond. Disulfide bonds are relatively strong- they aren't broken by changes in pH or high temperature
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