Proteins 2: Protein structure and bonding 2.2.9 Flashcards
What is the primary structure?
The sequence of amino acids found in a molecule,
(The gene that encodes the protein), which determines the function of the protein.
What is the secondary structure?
The coiling or folding of an amino acid into an alpha helix or beta pleated sheet - which arises from hydrogen bond formation
What is the tertiary structure?
The overall three-dimensional shape of the protein - which forms due to interactions including hydrogen bonds, disulphide bridges, ionic bonds, and hydrophobic/hydrophilic interactions.
What is the quaternary structure?
A protein structure which consists of one or more polypeptide chain.
Where do hydrogen bonds occur in amino acids?
Hydrogen bonds form between the carboxyl group and amino groups in an amino acid - as the hydrogen atoms in these groups are either slightly positively or negatively charged (in the secondary structure).
Where do ionic bonds form in amino acids?
Between carboxyl and amino groups that are part of the R groups (tertiary structure). These ionise into NH3+ and COO- groups.
Where do disulphide links occur in proteins?
Formed between the R groups of two cysteines- as they contain sulfur. These are strong links.
How do hydrophobic and hydrophilic interactions happen in proteins?
Hydrophobic parts of the R group tend to associate together in the centre of the polypeptide to avoid water - and the hydrophilic parts are found at the edge of the polypeptide (close to water).
These interactions cause twisting of the amino acid chain, which changes the shape of the protein.
