Proteins Flashcards
How many amino acids are there?
20
What is a dipeptide?
Two amino acids joined together
What is a polypeptide?
When two or more amino acids join together
What reaction links amino acids together?
Condensation reaction
What bond links amino acids together?
Peptide bonds
Other than carbon and hydrogen what makes up the structure of an amino acid?
Variable ‘R’ group
Carboxyl group
Amino group
Name the structural levels of a protein
Primary
Secondary
Tertiary
Quaternary
Describe the primary structure of a protein
A sequence of amino acids in a polypeptide chain
Describe the secondary structure of a protein
Hydrogen bonds form which causes the polypeptide chain to either coil into an alpha helix or fold into beta pleated sheets
Describe the tertiary structure of a protein
The polypeptide chain is coiled or folded further, and more bonds form (hydrogen and ionic). Disulfide bridge also form when 2 molecules of amino acid cysteine come together.
Describe the quaternary structure of a protein
The way multiple polypeptide chains are assembled together
Describe the functions of proteins
Enzymes: spherical tight folding polypeptide chains that are soluble are are involved in metabolism
Antibodies: involved in the immune response. 2 light and 2 heavy polypeptide chains bon together and have a variable region
Transport proteins: channel and carrier proteins help molecules and ions to travel across membranes
Structural proteins: strong. Consist of long polypeptide chains lying parallel to each other with cross links between them
Explain how you would test for protein
Biuret Test
- add a few drops of sodium hydroxide solution to make the solution alkaline
- add some copper (II) sulfate solution
- if a protein is present the solution will turn purple
