Proteins Flashcards
(22 cards)
What are the monomer that make up polypeptides?
Amino acids
What do polypeptides combine to form?
Proteins
What are the four chemical groups attached to the central carbon atom in an amino acid?
- Amino group (NH3)
- Carboxyl group (COOH)
- Hydrogen atom (H)
- R (side) group
What determines the differences between the 20 naturally occurring amino acids?
The R (side) group, which varies between each amino acid
What type of reaction forms a peptide bond between two amino acids?
Outline the full process of forming a peptide bond
> What is removed during the formation of a peptide bond
> What groups combine to form a peptide bond?
A condensation reaction occurs between two amino acids to form a dipeptide. The -OH from the carboxyl group of one amino acid and the -H from the amino group of another come together form the peptide bond, with the removal of a water molecule.
What is a dipeptide?
A molecule formed when two amino acids join together by a peptide bond
How can a peptide bond be broken?
By hydrolysis, which involves the addition of a water molecule
What is polymerisation in the context of proteins?
The process in which many amino acid monomers join together through condensation reactions to form a polypeptide
What is the primary structure of a protein, and what determines the primary structure?
The specific sequence of amino acids in a polypeptide chain, which is determined by the DNA
How does the primary structure of a protein determine its function?
The sequence of amino acids dictates the protein’s shape, which is essential for its specific function
What happens if a single amino acid in the primary structure is changed?
It may alter the protein’s shape, affecting or preventing it’s ability to function
What is the secondary structure of a protein, and what is the main bond responsible for the secondary structure of proteins?
This is the structure that forms when weak hydrogen bonds form between the primary structures, causing the chain to twist into a 3D shape (like a helixes or beta pleated sheets)
What is the main difference between a a-helix and a B pleated sheet?
An a - helix is a coiled structure, while a B pleated sheet consists of polypeptide chains lying parallel or antiparallel in a folded, sheet - like arrangement
What is the tertiary structure of a protein?
The tertiary structure occurs when there is even further twisting and folding of the secondary structure into a complex specific 3D shape
Why is the tertiary structure important for protein function?
It determines the protein’s shape, allowing it to recognise and interact with other molecules in a specific way
What are three types of bonds that maintain the tertiary structure of a protein?
Disulfide bridges
Ionic bonds
Hydrogen bonds
What are disulfide bridges?
Strong covalent bonds which are not easily broken
What are hydrogen bonds in the tertiary structure?
They are numerous but weak, easily broken by temperature or pH chaneges
How does the primary structure of a protein influence its tertiary structure?
The sequence of amino acids determine where bonds form, shaping the final 3D structure
What is the quaternary structure of a protein?
A structure where multiple polypeptide chains are linked together, sometimes with non - protein groups
How do polypeptide chains interact in the quaternary structure?
They are linked in various ways to form a larger, function protein
What is an example of protein with a quaternary structure?
Haemoglobin
