Protein Structure Flashcards
what are proteins used for in biochemical processes?
Catalysts e.g.enzymes Transporters Structural support Machines Immune protection Ion channels Receptors Ligands in cell signalling
What are proteins made up of?
Amino acids
What bonds form in proteins?
Peptide
What determines the amino acid sequences of a protein?
The nucleotide sequence of a gene
What does the folding of a protein depend on?
3D shape depends on the chemical and physical properties of the amino acid
What is an amino acid made up of?
An amino group -NH2
A carboxyl group- COOH
A hydrogen atom
An R group
What is a zwitterion?
Ionised form of an amino acid
E.g. NH3+ and COO-
How are amino acids classified?
According to the chemical properties of the r group: Hydrophobic or hydrophilic Polar or non-polar Acidic, basic or neutral Aliphatic or aromatic
What is an amino acid residue?
What remains of an amino acid after it has been joined by a peptide bond to form a protein e.g. HNCHCH3CO
If the pK value is lower is the side chain more likely to be acidic or basic?
Acidic
If pK value is higher is the side chain more likely to be acidic or basic?
Basic
If the pH of the solution is lower than the pK them what will happen to the group?
It will be protonated
If the pH of the solution is greater than the pK value then what will happen to the group?
It will be deprotonated
What is primary structure?
The linear amino acid sequence of the polypeptide chain
What is secondary structure?
Local spatial arrange of polypeptide backbone e.g. Alpha helix
What is tertiary structure?
The overall 3D configuration of the protein
What is the quaternary structure?
Association between different polypeptides to form multi-subunit proteins
How are peptide bonds formed?
Linking of two amino acids by the abstraction of a water molecule
How do peptide bonds lie?
Planar
All lie in the same plane
Why are peptide bonds so rigid?
Has a partial double bond characteristic
Unable to rotate
Are peptide bonds cis or trans?
Trans
Which bonds in a peptide bond are free to rotate?
Bond on either side of the bond