Proteins and their Functions Flashcards
3 factors affecting protein structure
- R groups
- Environment
- Chaperone proteins
What properties can R groups have?
- Charged
- Non-polar
- Hydrophobic
Types of secondary structure
- Alpha helix
- Beta sheets
What bonds stabilise secondary structure
Hydrogen bonds
What way do R groups face in secondary structures?
- Alpha helices = outwards
- Beta sheets = either side
What determines the tertiary structure of a protein?
The structure with the lowest energy (eg. negative R groups not next to each other)
Different tertiary structures
- Fibrous
- Beta-pleated sheet
- Helix
- Globular
Protein functions
- Binding
- Catalysis
- Switching
- Structural roles
How does phosphorylation of a protein affect function?
Negative phosphate groups change overall structure
Where is the phosphate group added?
R group of amino acids
What enzymes regulate (de)phosphorylation?
- Phosphorylation = kinase
- Dephosphorylation = phosphatase
What does a sorting signal do?
Directs protein to correct part of cell
Different vesicles in the secretory pathway and their function
- Transport vesicles = move protein from one compartment to another
- Secretory vesicles move proteins across membrane to be secreted
Where are proteins modified?
- ER mainly
- Further modification in Golgi
Examples of protein modification
- Phosphorylation
- Disulphide bonds
- Glycosylation (sugar added)
