Foundations in Biology Module 3.7 Types of proteins Flashcards
What are the features of globular proteins
- Compact
- Water soluble
- Roughly spherical
- Hydrophobic R groups are away from aqueous environment
- Hydrophilic R groups are outside the protein
What is the role of globular proteins
The regulation of many processes e.g. chemical reactions, immunity, muscle contraction
What are examples of globular proteins
- Insulin
- Conjugated proteins
Features of insulin
It regulates blood glucose concentration
- Transported in the bloodstream so must be soluble
- Need to fit specific receptors on cell-surface membranes so they have precise shapes
What is a feature of a conjugated protein
It consists of an a non-protein component called a prosthetic group
What are simple proteins
Proteins that do no have prosthetic groups
What are the types of prosthetic groups
-lipoproteins
-glycoproteins
-metal ions e.g. haem groups with iron
What contains haem groups
- Haemoglobin
- Catalase
What are the features of haemoglobin
- A quaternary protein
- Red oxygen carrying pigments in RBCs
- 4 polypeptides
- 2 alpha and 2 beta subunits
- Each subunit contains a haem group
What are the features of catalase
- Enzyme
- catalyses reactions and increases the rate
- A quaternary protein
- 4 haem groups
What does FE2+ ions allow catalase to do
Interact with hydrogen peroxide and speeds up its break down
What is hydrogen peroxide and what does a high concentration of it cause
A by product of metabolism
- it damages cells ans cell components
What are the features of fibrous proteins
- They form long, insoluble molecules
- They have a high proportions o amino acids with hydrophobic R groups in their primary structure
- Strong
- Don’t fold into a 3D shape
What are examples of fibrous proteins
Keratin, Elastin and collagen
What are the features of keratin
- There are groups of fibrous proteins in hair, skin and nails
- Large proportion of sulfur containing amino acids allowinf disulfide bridges
- Strong
- Inflexible
- Insoluble
