ILA 1 - IMMS Flashcards
Transcription (what is it, location, stages)
production of mRNA, Nucleus of cell
initiation, elongation, termination
Process of transcription
RNA polymerase binds to the promoter region, elongation occurs as the RNA polymerase moves in a 5-3 direction attaching nucleoside triphosphates . RNA polymerase reaches the terminator enzyme detach and the DNA rewinds
Topoisomerase
Unwinds the DNA section
Topoisomerase
Unwinds the DNA section
TATA box
30 bases long which is a binding sight for transcription factors
TATA box
30 bases long which is a binding sight for transcription factors
Transcription factors
class of protein that bind to promoter on DNA to activate transcription –> control gene expression
Splicing
introns removed from the mRNA
Translation (what is it, location)
producing polypeptides from mRNA, occurs in the cytoplasm of a ribosome.
Start codon
AUG –> methionine
tRNA
tRNA molecules bind to a specific amino acid. And the other end have a specific anti-codon
Stages of translation
large ribosome sub unit binds the start codon to the P site, ribosome moves along towards 3’ end. Peptide bond formed between AA in P and A site (peptidyl transferase). Continues till it has reached a stop codon
Single nucleotide polymorphism (SNP)
Variation at a single nucleotide position in a DNA sequence (occurs on 1 in 300 bases). Often does not cause any issues
Mis-sense variation
One base to another base
Non-sense variation
changes the base to make a stop codon
Sickle cell mutation
Single nucleotide substitution A –> T (glutamic acid to valine) GAG –> GTG
consequences of nucleotide alteration
different complimentary base pairing, different anti-codon, different AA, different polypeptide chain, different primary structure, different protein shape, different function
Conformation change in sickle cell (protein level)
glutamic acid –> valine.
abnormal beta globin = HbS. The amino acid is less polar = favours hydrophobic reactions causing S sub units to stick together to form long rigid molecules. Sickle cell from the internal binding to cytoskeleton
conformation change of haemoglobin consequences
haemoglobin becomes less soluble under decreasing oxygen concentrations = polymerises into crystals. Loses elasticity so cannot fit through capillaries = endothelial damage and inflammatory response = pain and can cause ischaemia
How is sickle cell inherited?
autosomal recessive genetic condition
Treatment of sickle cell
Can be treated with feotal Hb which increases the concentration of NO = increases transcription of gamma haemoglobin (not beta) so no deformity
