lecture 16 transcription Flashcards
what was cricks proposal
the central dogma of molecular biology was DNA to mRNA to Protein
what are the three steps of transcription
initiation, elongation and termination
what is splicing
the process of remvong introns from the mRNA strand and putting exons together to make a functional mRNA
what 3 things does the 5’ G cap do
prevents mRNA degradation, promote intron excision and provides a binding site for the small ribosomal subunit
what 2 things does the 3’ poly a tail do
Prevents mRNA degradation and facilitates export of the mRNA from the
nucleus to the cytoplasm
what are the main functions of the 5’ and 3’ UTR’s
Contain regulatory elements (sequences) that influence on gene expression at the transcriptional and/or translational level
§ 5’ UTR facilities the addition of the 5’ G cap
§ 3’ UTR facilitates the addition of the polyA tail
what happens during elongation
RNA pol II uses the template strand, which runs in the 3’ → 5’ direction, as a template, and inserts
complementary RNA nucleotides in the 5’ → 3’
direction
whats the central dogma of molecular biology
a theory stating that genetic information flows only in one direction, from DNA, to RNA, to protein, or RNA directly to protein.
what are the three steps of translation
initiation, elongation and termination
what is step 1 of initiation
Transcription factors bind to
the TATA box and other
regions of the promoter.
what is step two of initiation
RNA pol II binds, forming a
transcriptional initiation
complex together with the
transcription factors.
what is step 3 of initiation
The two DNA strands are separated by the RNA polymerase 2 and RNA synthesis starts without the need of a primer. DNA can be separated without helicase. RNA pol 2 and transcription open and close the DNA like a zip.
what is a charged tRNA
a tRNA which has an amino acid attached to it
how is the tRNA charged
An enzyme (aminoacyltRNA synthetase),
recognises both a specific
amino acid and the
correct tRNA for this
amino acid and joins
them together. there is one enzyme complex with each amino acid
what happens in termination
stop codon stops RNA polymerase two from adding the nucleotide bases to the strand.
The end result of this process Is pre-mRNA, this pre-mRNA then gets processed to form mature RNA which leaves the nucleus for the ribosomes where it is translated into amino acid sequences.
