Nucleic acids and proteins Flashcards
Define a protein
Proteins are biomacromolecules built of amino acid subunits and linked by peptide bonds to form a polypeptide chain.
Define a polymer
Large molecules made of identical or similar single units
Define a monomer
Small sub-units of the large unit of cells (polymer)
What is the main function of proteins?
Controls metabolic processes in the cell.
What are the main elements that proteins contain?
- Nitrogen
- Oxygen
- Carbon
- Sulfur (smaller quantities)
- Phosphurous (small quantities)
What is an amino acid?
Monomer of proteins
How many amino acids do we have in our bodies?
20 different amino acids
Draw the general formula of an amino acid
R
|
NH2 - C - COOH
|
HWhat is the name given to the NH2 group and R group respectively?
Amine group and R group
What is the importance of the R group?
The R group is variable, so different amino acids have different R groups. Thus, the R group is important as it produces variation within amino acids and thus different functioning etc. (remember all other parts, excluding the R group is identical)
What should you look for when determining an amino acid?
R group and Nitrogen element
When two amino acids join, what does it form? What about three?
Dipeptide and a tripeptide
What joins amino acids
peptide bonds
Why is the structure of a protein important?
Allows it to perform its particular role and function.
How many levels of organisation do proteins have?
4
Why is the structure/shape of a protein important?
Allows it to perform its particular role and function. If a protein’s shape is changed, it can no longer function. If the shape is permanently it is
SECONDARY STRUCTURE
- Define
- Describe the structure
- Hydrogen bonds between neighbouring peptide groups result in the localised coiling and folding of segments of the polypeptide chain to help stabilise a 3D shape.
- Have 3 distinct structures
ALPHA HELIX: protein chain is loosely coiled and is held by h-bonds
BETA PLEATED SHEETS: chains are folded so they lie alongside each other, where folded chains are again held by h-bonds.
RANDOM COILING: proteins do not conform to either an ALPHA HELIX or BETA PLEATED STRUCTURE.
TERTIARY STRUCTURE
- Define
- Describe the structure
- Total irregular folding held together by ionic or h-bonds to form a complex shape.
- 3D structure due to global coiling and folding which becomes critical for the protein’s functioning.
Bonds important: - Ionic bonds
2.Covalent disulfide bonds
3.H-bonds
4.Hydrophobic interactions.
QUATERNARY STRUCTURE
- Define
- Describe the structure
1/2. occurs in proteins with multiple polypeptide chains which are joined by the same 4 interactions in the tertiary stage to form the final protein.
- associate with non-proteic groups
- either globular or fibrous
Define denaturation
the loss of the 3D structure and usually also the biological function of a protein, which is often but not always permanent.
Factors affecting denaturation
- Heavy metals: disrupt ionic bonds, reduce protein charge
- Strong acids and alkalies: disrupt ionic bonds
- Heat and radiation: disrupt bonds in proteins through increased energy provided to the atoms
- Detergents and solvents: form bonds with non-polar groups in the protein, disrupting h-bonds
- pH
