The Structure Of Proteins Flashcards
How many different types of amino acids are there
20
Primary structure
The sequence of amino acids in the polypeptide chain
What’s a peptide bond
A covalent bond between each amino acid
Why do secondary structures form
It’s because of the hydrogen bonding between the different amino acid chains
What are the names of the secondary structures
A-helix and B-pleased sheets
How is the tertiary structure formed
The secondary structure folds to form a very precise 3-D structure. The forces responsible for this are hydrogen bonds, ionic bonds, disulphide bonds and van der walls forces
How do amorphous regions occur
They occur where the molecules have an amino acid sequence that does not participate in B-pleated formation
Ionic bonds
Can be split by changing the Ph
Not temperature sensitive
Are in a solution
Disulphide bonds
Pretty strong
The more disulphide bonds the more stable it is
Can be split by reducing agents
Van der walls forces
Weak forces of attraction between non polar groups
Water excluded from these hydrophobic side chains, helps keep the side chain together
Can be easily split by temperature rise
the bonds in order of there strength ( smallest to largest)
Van der walls forces
Hydrogen bonds (dipole dipole)
Ionic bonds
Disulphide bonds
Globular proteins
They form a spherical mass with a specific 3-d shape ( tertiary and quaternary)
In an aqueous solution They fold up so that hydrophilic groups are on the outside and hydrophobic groups are inside the molecules
Quaternary structure
More than 1 polypeptide chain held together in a precise 3-d structure
Held together by the same forces responsible for them formation of tertiary structure
In haemoglobin there is 2 a-chain subunits and 2 a-chain subunits and 4 haem groups and 4 polypeptide chains .
Fibrous proteins
They form long chains of fibres( they have primary secondary tertiary and quaternary structures)
Insoluble in water, this makes them useful for structure and support
In collagen Fibres form a triple helix of polypeptide chains, these chains are held together by hydrogen bonds
How are dipeptides formed
The condensation of 2 amino acids
