Proteins Flashcards
What are the three parts to an amino acid?
• Amine group
• ‘R’ group
• Carboxyl group
What bonds are formed when joining amino acids together?
Peptide bonds
What are three or more amino acids joined together called?
Polypeptide
Why is the primary structure of a protein important?
It helps determine the final 3D shape of the protein molecule
How do hydrogen bonds form between amino acids all along the polypeptide chain?
• Oxygen atoms in the C=O (carboxyl) groups have a small negative charge
• Hydrogen atoms in the N-H (amine) groups have a small positive charge
• Hydrogen and oxygen atoms are attracted to each other, forming hydrogen bonds
What is the secondary structure of a protein caused by?
Folding of the protein due to hydrogen bonds forming between oxygen and hydrogen atoms
What are two types of secondary structure?
• Alpha helix
• Beta pleated sheet
What is the tertiary structure?
The overall 3D shape of a polypeptide chain
What are prosthetic groups?
Non-protein molecules that form part of the structure of a protein
What are proteins containing prosthetic groups called?
Conjugated proteins
What are the properties of globular proteins?
• Compact
• Water-soluble
• Roughly spherical
Why are globular proteins soluble in water?
Their hydrophilic R-groups are on the outside of the protein
What are three examples of globular proteins?
• Haemoglobin - red blood cells
• Insulin - blood glucose regulation
• Catalase - speeds up hydrogen peroxide breakdown
What are the properties of fibrous proteins?
• Long
• Insoluble
• Limited range of amino acids
• Usually have small R-groups
• Amino acid sequence in the primary structure is usually quite repetitive
Why are fibrous proteins insoluble?
They have a high proportion of amino acids with hydrophobic R-groups in their primary structures
