2.1.2 Protein and Inorganic ions Flashcards
What is the primary structure of proteins?
The number and sequence of amino acids in the polypeptide chain.
What is the secondary structure of proteins?
The coiling or regular folding of the polypeptide chain, held together by hydrogen bonds.
What is the tertiary structure of proteins?
The further folding of the polypeptide chain to form a precise, compact and geometric shape. It is held together by hydrogen bonds, disulfide bonds, ionic interactions and hydrophobic and hydrophilic interactions.
What is the quaternary structure of proteins?
Proteins which contain two or more polypeptide chains.
What are the monomers of a polypeptide chain called?
Amino acids.
What are 2 types of proteins?
Globular proteins and fibrous proteins.
What is the shape of a globular protein?
Roughly circular/spherical
What is the shape of a fibrous protein?
Long and thin strands
What determines the function of a protein?
The shape, so the type and number of amino acids within a polypeptide chain.
What is the general structure of an amino acid?
A central carbon atom bonded to an amine group (NH2), a carboxylic acid group (COOH), a hydrogen atom and an R group.
What is the covalent bond called that forms between an amino acid?
Peptide bond.
How is a peptide bond formed?
A hydroxyl (-OH) is lost from the carboxylic group of one amino acid and a hydrogen atom is lost from the amine group of another amino acid. The remaining carbon atom (with the double-bonded oxygen) from the first amino acid bonds to the nitrogen atom of the second amino acid.
What is the reaction called when the bond is formed?
Condensation reaction.
What is the primary structure of a polypeptide chain determined by?
The DNA of the cell.
What are the 2 types of secondary structures of a protein?
Alpha helix and Beta pleated sheet.
how do alpha helix form
the hydrogen bonds form between every fourth peptide bond.
how do beta pleated sheet form?
the protein folds so that two parts of the polypeptide chain are parallel to each other enabling hydrogen bonds to form between parallel peptide bonds.
What are the additional bonds that can form between the R groups?
Hydrogen bonds, disulfide bonds, ionic bonds and weak hydrophobic interactions.
Where do disulfide bonds form?
Between two cysteine R groups as they are the only amino acid with a sulfur atom.
Where do ionic bonds form?
Between positively charged and negatively charged R groups.
When do hydrogen bonds form?
Between strongly polar R groups.
What is the structure of haemoglobin?
conjugated protein with a tertiary structure with 4 polypeptide chains. These chains are globin proteins and all contain a prosthetic haem group. The chains are held together by disulfide bonds and by hydrophobic and hydrophilic interactions.
How does the structure of haemoglobin help its function?
The haem groups contain Fe 2+ ions which is able to reversibly combine with oxygen to form oxyhaemoglobin.
What type of protein are enzymes?
Globular proteins.
