1.3 Proteins Flashcards
Describe the structure of an amino acid
———-R
H - N - C - C - OH
H O
How is a protein formed?
2 amino acids in a condensation reaction forming a peptide bond
What are the roles of hydrogen bonds in the structure of proteins?
- weak bonds but they can form between any 2 amino acids
- can break and reform easily
- important for folding and coiling of polypeptide chains
What are the roles of disulfide bonds in the structure of proteins?
-form when 2 cystine molecules are close together in a polypeptide
- very strong bonds
- important for holding folded polypeptide chain in place
What are the roles of ionic bonds in the structure of proteins?
- form between strongly positive and negative amino acid side chains
Describe the primary structure of a protein
linear sequence of amino acids held together by peptide bonds
Describe the secondary structure of a protein
arrangement of the polypeptide chain into a regular, repeating structure held together by hydrogen bonds
- alpha helix
- beta pleated sheets
- most fibrous proteins are secondary
Describe the tertiary structure of a protein
3D structure of secondary chain
hydrogen, disulfide and ionic bonds hold the structure in place
- globular proteins are tertiary
Describe the quaternary structure of a protein
only seen in proteins with several polypeptide chains
How does the structure of collagen relate to its function?
- a strong fibrous protein - gives strength to tendons, ligaments, bones, skin
- made up of 3 polypeptide chains - 3 alpha chains arranged in triple helix
How does the structure of haemoglobin relate to its function?
- a globular protein
- very large molecule arranged in 4 polypeptide chains, held together by disulfide bonds
- conjugated protein - iron enables haemoglobin to bind and release oxygen
- arrangement of polypeptide chain determines how easily oxygen binds/is released
