Proteins and carbohydrates Flashcards
What are proteins also known as?
Polypeptides
What are proteins also known as?
Polypeptides
What are proteins?
Polymers of amino acids with an amine group at the N-terminus (beginning of protein) and a carboxyl group at the C-terminus (end of protein).
What is the alpha carbon, Cα?
The carbon where the R group is connected.
How are amino acids joined together?
By peptide bonds that are produced by a condensation reaction between an amine and carboxyl group.
H of Amine group of amino acid 1 + O-H of Carboxyl group of amino acid 2 —> Peptide bond + Water
What are some properties of an amino acid that the R groups determine?
Charge, polarity, and affinity for water.
What is the primary structure of a protein?
The linear sequence of amino acids. It contains all the information that the protein needs to fold.
What is the secondary structure of a protein?
The regular structure of the local (repeating) segments of the protein backbone produced through intramolecular hydrogen bonding between the protein backbone.
Why do amino acids only have a few allowed conformations?
The rigidity of the amine bond means that there are only two freely rotating single bonds per amino acid in a peptide backbone, characterised by two dihedral angles.
What are the three most well-known secondary structures of proteins?
α-helices, β-strands, and β-sheets.
What parts of what diagram show the possible dihedral angle combinations of an amino acid?
The non-white regions on a Ramachandran plot.
What is the tertiary structure of a protein?
The 3D shape of the protein (3D arrangement of its polypeptide chain) which is governed by the interactions of secondary structure elements with each other.
A sequence of amino acids not forming any secondary structure is said to be…
…intrinsically disordered.
What is the quaternary structure of a protein? What is holding it together?
The association of several protein chains into a closely packed arrangement (combination of multiple proteins). Proteins are bonded by weak covalent or by non-covalent bonds.
Which is more stable (i.e. the preffered state of a protein) (i.e. has less free energy), a folded or unfolded protein?
Folded protein
