Globular and fibrous proteins Flashcards
what is a fibrous protein
Long ,thin, Regular and repetitive sequence of amino acids, usually insoluble in water
what is a globular protein
tend to roll up into a spherical shape, usually soluble in water.
what role does fibrous proteins usually have in organisms and why
Structural role- repetitive structure of amino acids.
Insoluble in water
Long and thin
How does the solubility of globular proteins ensure their role in an organism
Globular proteins have a Metabolic role in organisms due them being soluble in water
the hydrophobic R group is turned inwards whilst the hydrophilic parts of the amino acid are on the outside
The solubility allows them to be easily transported around organisms
How is the shape of a fibrous protein different to a globular protein
Fibrous- Long and Thin
Globular- Spherically shaped
What is the function of Collagen.
Give an example
Function- to provide mechanical strength
E.G- In artery walls to prevent bursting
E.G- Bones
E.G- Cartilage
what are three examples of Fibrous proteins
Keratin
Collagen
Elastin
The function of Keratin is to make molecules hard and strong to provide Protection, what features of Keratin allow it to perform its role
Keratin has lots of cysteine which means it has disulphide bridges and Hydrogen bonding in its polypeptide chains.
How does Keratin provide protection from infection
Keratin is also waterproof, creates an impermeable barrier to water-borne pollutants or pathogens
What is the function of Elastin
Allows stretch and recoil or adaptations of shapes
How does elastin allow things to stretch
Due to cross linking and coiling allows Elastin to be extensible
What parts of our body have Elastin
Lungs- allow inflation and deflation
Skin- stretches around bones
What 4 polypeptide chains make up the quaternary structure of haemoglobin
2X a-globin chains
2X b-globin chains
Each of these chains have their own tertiary structure providing a very specific shape.
What is the prosthetic group used in haemoglobin
A Haem group- containing an iron ion.
-oxygen binds to the iron ion in haemoglobin
What is the name given to a protein with a prosthetic group
Conjugated protein
E.G Haemoglobin (Globular protein)
Insulin is a Globular protein, it consists of two polypeptide chains.
Describe these 2 polypeptide chains
- Polypeptide chain A: Begins with a section of alpha-helix
has 21 amino acid residues
-Polypeptide chain B: ends with a section of Beta-pleated sheet
has 30 amino acids
Are haemoglobin and Insulin soluble in water
yes they are, due to hydrophilic R groups on the outside of the molecule .
Pepsin is a globular protein. How many polypeptide chains make up Pepsin
One
Pepsin consists of one singular polypeptide chain which folds into a tertiary structure
Relating to R groups, how is pepsin so stable in acidic environments
Pepsin has a lot more acidic R groups than basic R groups which will accept H+ ions.
What bonds are used in a pepsin enzymes
Peptide
Hydrogen
Disulfide bridges
Ab initio protein modelling and Comparative protein modelling are both ways scientists can predict protein shape.
What are the differences between the two
Ab initio protein modelling-
model based off electrical properties in atoms in each amino acid.
Comparative protein modelling-
Protein threading, scans the amino acid sequence and gives possible models which match the sequence
