Lecture 15 Flashcards
What must happen to the tRNA before it goes to translation?
before translation iccurs need to charge up the tRNA-add an amino acid to tRNA then calle aminoacyl-tRNA
What are the bases on the tRNA called?
anticodon (3 bases)
How is the tRNA charged up?
- A specific amino acid and ATP bind to the aminoacyl-tRNA synthetase 2. AMP is covalently bound to the amino acid thereby activating it and pyrophosphate is released 3.The correct tRNA binds to the synthetase. The amino acid is covalently attached to the tRNA, AMP is released 4.The charged tRNA is released
How is initiation in translation started?
-need to find the start of the gene to start translation, some transcribed bits don’t go into translation so have to find the start, recognition sequence on the RNA telling the ribosome where to bind
Describe initiation in translation.
first binding is the small subunit of the ribosome (made up of rRNA and protein), the binding site is upstream of the start of the RNA that’s going to be translated into the polypeptide,
-when recognition sequenc eon RNA then small subunit moves,know that AUG is close by, first tRNA has anticodon UAC, in prokaryotes special Methionine
then large subunit binds, create grooves with the small important for translation
initiation: recognition of binding site, translocation of small subunit to AUG, then finished
Describe elongation in translation?
fMet- the first tRNA in prokaryotes
the bases are read 5’- 3’
peptidyl site (orange) - P site, the other A site (amino acyl)
-trial and error with codon anticodon match, tRNA tries to get a match, wobbles and if not leaves
How is translation terminated?
UGA- one of the stop codons, no anticodon for this one, attracts a protein called the release factor= stop codon intiates the positioning of the relase factor on the ribosome then everything dissociates
-polypeptide leaves, mRNA leaves- can be translated again
ribosomal subunits dissociate and the release factor is recycled so can be used again
Which site does the tRNA go to first?
it’s only the fMet that goes in to the P site first all the other
go into the A site first
What is proteome?
part of the genome that will produce protein
What are Genome,Proteome,Transcriptome,Metabalome,Epigenome?
Genome – DNA sequence Proteome – proteins Transcriptome – expressed DNA sequences Metabalome –pathways in cell meatbolism Epigenome – epigenetic state of a cell,part of DNA that can be methylated, involved in epigenetics
What is a mutation?
Mutations are any alteration in DNA sequence from a single base pair substitution, deletion, insertion or several base pairs or a major alteration in the structure of a chromosome
many genes more than two alleles, arisen by mutations
mutations can be gross, but can also be on one base
What is somatic and germ line mutation?
also can be classified as- somatic- occuring in somatic tissue (cells), this will die with the individual, not passed on to the next generation
germ line- consequences for next generation
What is a spontaneous and induced mutation?
spontaneous= just happens,lot of mutations like that (Duschenne etc. can just appear in a family with no history)
induced= caused by the environment
What are mutagens?
- factors causing induced mutations
- can even predict what type of mutation
What is a chromosomal mutation?
gross mutations – deletions translocations involve many genes if visible
under a light microscope - 4Mb approx 200 -300 genes
-can have chromosomal mutations- if you can see that it lost a piece, swapped a piece, dealing with at least 200 genes= gross mutation