proteins Flashcards
What kinds of proteins provide support?
Collagen (the protein of the bone), skin and tendon
Tell me about collagen fibres
These are the main component of connective tissue
Found in skin, tendons, organs and bone
What are erythrocytes
This is another name for a red blood cell
Tell me about haemoglobin
Selective delivery of O2 to metabolic tissues
4 protein subunits per molecule
Each subunit contains a haem group that can bind one oxygen molecule
Haem is an example of a prosthetic group
What are LDLs composed of?
a phospholipid shell and a single molecules of apolipoprotein
What are LDLs used for?
To transport cholesterol between cells via the circulatory system
What is the uptake of LDL particles mediated by
the LDL receptor that binds LDL and facilitates internalisation
What condition is associated with a mutation in the LDL receptor gene
Hypercholesterolemia
Describe the structure of antibodies
There are two identical heavy chains and two identical light chains covalently linked by disulphide bonds
The antigen recognition site is highly specific and tightly binds the complementary antigen allowing recognition of foreign proteins by the immune system
Lysozyme is an exmpale of a biological catalyst: describe it
It catalyses the cutting of polysaccharide chains
Lysozyme binds to the polysaccharide chain, catalyzes the cleavage of a specific covalent bond and releases the cleaved products
lysozyme remains unchanged at the end of the reaction
What kind of protein regulates genes?
the lac repressor - helps controls gene expression
Describe the lac repressor
Controls production (expression) of proteins metabolising lactose in bacteria The repressor binds to DNA and prevents expression of the gene in the absence of lactose
what do the functions of protein come down to
SPECIFIC BINDING = CHANGE OF CONFORMATION = CHANGE OF ACTIVITY
What bonds are proteins joined by
peptide bonds
Whats the structure hierarchy of proteins
PRIMARY - SECONDARY - TERTIARY - QUATERNARY
What is the general structure of an amino acids
An amino group, a carboxylic acid and a unique side chain
What does the r-group determine
the structure and function of the protein
Name the hydrophilic amino acids
Lysine, arginine, histidine - basic
aspartate, glutamate - acidic
Serine, threonine, asparagine, glutamine - polar uncharged r-groups
Name the hydrophobic amino acids
alanine, valine, isoeucine, leucine, methionine, phenylalanine, tyrosine, tryptophan
Name the special amino acids
Cysteine, glycine, proline
what is special about cysteine
it can form covalent disulphide (-s-s-) bons with other cysteine residues
What is special about glycine
It is the smallest amino residue and can fit into tight spaces