Proteins Flashcards
1
Q
What are proteins?
A
- large molecules, polymers of amino acids
2
Q
What enzyme catalyses formation of peptide bonds ?
A
- peptidyl transferase
3
Q
What are peptides?
A
- between 2 and 50 amino acids
4
Q
What are 3 methods of post-translational modification of proteins?
A
- Proteolysis = polypeptide chain cleaved into fragments
- glycosylation = addition of sugars
- phosphorylation
5
Q
What kind of hormone is insulin + where is it produced?
A
- Peptide hormone produced in 𝛃 of pancreas
6
Q
function of proteins ?
A
- enzymes
- structural support
- hormones
- cell signaling
7
Q
what do amino acids form at low and high pH’s ?
A
- form cations in low pH
- anions in high pH
8
Q
how many amino acids does a polypeptide chain contain ?
A
- polypeptide chain between 50 and 2000 amino acids
9
Q
what is the primary structure of a protein ?
A
- sequence of amino acids in polypeptide chain
10
Q
What is the secondary structure of a protein ?
A
- localized folding patterns within the polypeptide chain
- stabilized by H bonds
- α-helix and β-pleated sheets
11
Q
What is the α-helix (𝛼-helix), and how is it structured?
A
- right-handed spiral structure
- each C=O forms a H bond with the NH of the amino acid four residues earlier
12
Q
What is the β-pleated sheet (𝛃-sheet) ?
A
- 2 or more lengths of the polypeptide chain lie parallel to each other
- R groups of the amino acids point above and below the sheets
- NH and C=O parts of the peptide bond point towards each other
- H-bonds between these sections
13
Q
What is the tertiary structure of a protein?
A
- final 3D shape, which is determined by the interactions between the R-groups
14
Q
What are the four main types of interactions that stabilize the tertiary structure of proteins?
A
- Ionic bonds
- Hydrophobic interactions
- Hydrogen bonds
- Disulphide bridges = (covalent)
15
Q
What is the quaternary structure of a protein?
A
- two or more polypeptide chains interact
- Forces between these chains, SAME AS TERTIARY structure
