generating diversity Flashcards
what is the priamry structure of a protein?
the sequence of amino acid that codes for a gene
what is the secondary structure of a protein?
folds of amino acid sequence to make alpha helices and beta pleated sheets
what is the tertiary structure of a protein?
overall 3D shape
what do alpha helices allow?
proteins able to insert into a membrane
what are beta pleated sheets?
bonds that make up beta sheets are incredibly weak (hydrogen), however there are many of them, making it stronger
aggregation (misfolded) by beta pleated sheets links to neurogenerative disorders
what is the quaternary structure of a protein?
multi-subunit assembly
the process of gene mutations result in…
related proteins with altered function
what does a point mutations result in?
altered primary sequence (e.g A swapped with G) by changing one nucleotide to a different one
effects= silence, misense and nonsense
how does insertion result in an altered primary sequence?
new nucleotides inserted resulting in different gene
how does deletion result in an altered primary sequence?
removes nucleotides resulting in a frame shift
gene duplication resulting in new proteins…
not initially translated due to stop codon however if a point mutation/deletion occurs in stop codon then there will be two copies of a single gene
what channels evolved by gene duplication?
sodium (duplicated 4 times) and calcium ion channels
relation of metabotropic glutatmate receptors
phylogenetic relation of G-protein coupled receptors fall into 3 groups that are dependent on sequence similarity and act in different signalling mechanisms
group 1 of G-protein coupled receptors
mGluR1 and mGluR5
group 2 of G-protein coupled receptors
mGluR2 and mGluR3
group 3 of G-protein coupled receptors
mGluR7, mGluR4, mGluR8 and mGluR6
how many receptors are in the GPCR superfamily?
> 1200 receptors
quaternary structure and ion channels
multiple individual proteins (monomers)
combine to form a ‘super-protein’ (multimer)
ion channels are multimeric assemblies
nAChR (nicotinic acteylcholine receptor) subunits?
5
NMDAR (glutamate receptors) subunits?
4
subunit composition
1=1
2=6
3=21
number of possible combinations increases with the number of available subunits and number of subunits required
GABAa receptor subunit composition
1000s of possible receptors from 13 genes but only a small number detected
what is alternative splicing?
process that occurs during the transcription of a gene, where the exons of the pre-mRNA are joined in different ways to produce multiple mRNA isoforms from a single gene
exon splicing can be variable e.g via exon skipping, creating splice variants (diffrential splicing)
what is diffrential splicing?
a form of alternative splicing but with an emphasis on the variation between different conditions or groups
