Protein Structure Flashcards
(20 cards)
What is a dipeptide?
Two amino acids joined together.
What is a polypeptide?
A chain of two or more amino acids joined together
What is a peptide?
The bond formed between amino acids
Describe the general structure of an amino acid.
- Carboxyl group (COOH)
- Amino group
- R group
How are polypeptides formed?
Condensation reactions that link amino acids together
- Water is produced as a by-product
What is hydrolysis?
When two molecules (amino acids) are broken apart by adding water.
What bonds appear in the primary structure?
Peptide bonds
What bonds appear in the secondary structure?
Hydrogen bonds between O and H
What bonds appear in the tertiary structure?
Ionic bonds, disulphide bonds, hydrogen bonds and hydrophobic or hydrophilic interactions.
How are ionic bonds formed?
Attractions between +ve and -ve parts of the secondary structure.
How are disulphide bonds formed?
When 2 cysteine molecules come close together and their sulphur atoms bond to each other.
How do hydrophobic and hydrophilic interactions affect the tertiary structure.
- Hydrophobic groups clump together when they are near each other in a protein.
- This causes the hydrophilic groups to be pushed to the outside of the protein and the hydrophobic parts move to the inside.
- This is also known hydrophobic exclusion.
Describe the quaternary structure.
- Dependent on tertiary structure and is influenced by all the bonds that may occur in the tertiary structure.
Describe the primary structure.
- The sequence of amino acids in a polypeptide chain.
- Amino acids held together by peptide bonds.
Describe the secondary structure.
- Folding or spiralling of primary structure into beta-pleated sheets or alpha helices
- Hydrogen bonds form between the O and H atoms of amino acids in the polypeptide chain.
Describe the tertiary structure.
- Polypeptide chains bend and fold to form precise shape
- More chemical bonds form maintain final tertiary shape
Describe the globular structure of a protein.
- Round, compact and made up of multiple polypeptide chains
- Hydrophilic parts of chain on outside and hydrophobic on the inside
How does the structure of a globular protein affect its functions?
- The hydrophilic (outside) and hydrophobic (inside) arrangement mean they are soluble and are easily transported in fluid.
Describe the structure of a fibrous protein.
- Long, insoluble, tightly coiled polypeptide chains
- Held together by lots of bonds
How does the structure of a fibrous protein affect its function?
- Lots of bonds mean it is a very strong protein
- Therefore, it is often found in supportive tissue.
