Structures of proteins Flashcards
What are the functions of LDL and LDL receptors?
LDL and LDL receptors transport cholestrol molecules and co-ordinated their uptake into cells
Give the features of cholesterol transport?
Cholesterol transport;
- Has a phospholipid monolayer shell
- Has a low-density lipoprotein and a single molecule of apolipoprotein B
- Used to transport cholesterol between cells via the circulatory system
What is the uptake of LDL particles mediated by?
The uptake of LDL particles is mediated by the LDL receptor that binds LDL and facilitates internalisation
What do patients who have a mutation in the LDL receptor gene suffer from?
Familial hypercholestrolemia - an abnormal uptake of cholesterol
What is atherosclerosis ?
Plaques can break off and cause blockages potentially becoming fatal
How are proteins used in defence?
Antibodies are made of proteins and defend against infection (they are highly specific)
What are antibodies specifically made from?
Antibodies are a glycoprotein as they have a sugar molecule attached
What are the features of the antigen recognition site?
The antigen recognition site is highly specific and tightly binds the complementary antigen allowing recognition of foreign proteins by the immune system.
The antigen recognition site is composed of two identical heavy chains and two identical light chains, both bonded by disulphide bonds.
What are the 2 types of biological catalysts and their functions ?
Enzymes - regulate all biological systems
Lysozymes;
- Catalyses the cutting of polysaccharide chains
-They bind to polysaccharide chains, catalyse the cleavage of a specific covalent bond and release the cleaved products, the lysozyme remaining unchanged at the end of the reaction.
What are the 2 types of biological catalysts and their functions ?
Enzymes - regulate all biological systems
Lysozymes;
- Catalyses the cutting of polysaccharide chains
-They bind to polysaccharide chains, catalyse the cleavage of a specific covalent bond and release the cleaved products, the lysozyme remaining unchanged at the end of the reaction.
How do proteins help control gene expression?
The Lac repressor is made of proteins which;
- helps to control the production (expression) of proteins that metabolise lactose in bacteria
- The repressor binds to DNA and prevents expression of the gene in the absence of lactose
What are proteins ?
Large complex lines polymers
- Large (usually many thousands of mass units)
- Complex (but have an underlying simplicity, chemically. they are linear polymers of amino acids)
- Linear polymers (Amino acids joined by peptide bonds)
What are proteins ?
Large complex lines polymers
- Large (usually many thousands of mass units)
- Complex (but have an underlying simplicity, chemically. they are linear polymers of amino acids)
- Linear polymers (Amino acids joined by peptide bonds)
What are proteins ?
Large complex lines polymers
- Large (usually many thousands of mass units)
- Complex (but have an underlying simplicity, chemically. they are linear polymers of amino acids)
- Linear polymers (Amino acids joined by peptide bonds)
Draw and name 3 basic hydrophilic amino acids?
Diagram
Draw and name 2 acidic hydrophilic amino acids?
Diagram
What kind of amino acid is Histidine ? Draw it
Basic amino acid
Diagram
What kind of amino acid is Aspartate? Draw it
Acidic amino acid
Diagram
What kind of amino acid is Serine? Draw it
Polar amino acid with an uncharged R group
Diagram
Draw and name the 3 special amino acids?
Cysteine, Glycine and Proline
Diagram
What is a special feature of Glycine?
Glycine is the smallest amino acid residue and this allows it to fit in tight spaces as it doesn’t have a bulky side chain
What is the special feature of proline?
The side chain of Proline bends around to form a covalent bond with the nitrogen atom of the amino group. By doing this Proline creates a kink in the protein chain.
What is an acid?
An acid is any molecule that tends to donate a hydrogen ion
What is a base?
A base is a molecule that readily accepts a hydrogen ion
How do we work out the Ka (equilibrium constant) of a reaction?
Ka = Concentration of products / Concentration of reactants
How can you work out the pKa of any acid?
The pKa of any acid is equal to the pH at which half the molecules are disassociated
How can you work out the pKa of any acid?
The pKa of any acid is equal to the pH at which half the molecules are disassociated
What causes pKa to vary?
pKa varies depending on the environment