Protein structure and bonding Flashcards
(27 cards)
What is the primary structure of a protein?
The sequence of amino acids found in the molecule.
What is the quaternary structure?
Protein structure where a protein consists of more than one polypeptide chain.
What is the secondary structure?
The coiling or folding of an amino acid chain, which arises often as a result of the formation of hydrogen bonds between different parts of the chain.
What are the main forms of the secondary structure?
The helix and the beta pleated sheet.
What is the tertiary structure?
The overall 3D shape of a protein molecule.
Why does the tertiary structure of a protein arise?
Due to interactions including hydrogen bonds, disulphide bridges, ionic bonds and hydrophobic interactions.
If one amino acid is changed in a sequence what is likely to happen?
The function of the protein changes.
The function of a protein is determined by what?
Its structure.
True or false. The primary structure has no affect on what will happen at the other stages.
False. The primary structure directly affects what shape the protein will take at the tertiary and secondary structure.
In an alpha helix and beta pleated sheet what molecules are the hydrogen bonds between?
The NH group and the CO group.
What makes the secondary structures stable at optimum temperature/pH?
The large amount of hydrogen bonds. Although they are generally weak interactions because of their number they cause the structures to be strong.
What are the variations of the secondary structure stage?
Some chains have both at either end and some amino acids chains don’t take a particular shape at all.
What is the tertiary structure?
When helix and pleats fold themselves.
In the tertiary structure what are the bonds between?
The amino acids.
If a protein adopts a supercoiled shape what is this called?
A fibrous protein.
If a protein adopts a spherical shape what is this called?
A globular protein.
What happens in the quaternary structure?
Multiple polypeptide chains are arranged to make a complete protein molecule.
Where do hydrogen bonds form?
Between hydrogen atoms with a slightly positive charge and other atoms with a slightly negative charge.
Bonds between polar areas of R-groups are key to holding which structures together?
Tertiary and quaternary.
Where do ionic bonds form?
Between the carboxyl and amino groups that are part of the R-groups.
What do the carboxyl and amino groups ionise into when an ionic bond is formed?
NH3+ and COO-
Why are ionic bonds very strong?
The positive and negative groups are strongly attracted to each other.
Where are disulphide links?
The R-group of the amino acid cysteine contains sulphur. Disulphide bridges form between two R-groups.
What are disulphide bridges a form of?
Strong covalent bonds.
