TRANSCRIPTION Flashcards
transcription is governed by
the principle of complementarity
how many dna strands code for rna
one strand
3to5
why only one dna strand act as a template for rna making
2 dna strands - 2 rna with different sequences - 2 different AA sequences in protien AND 2 rna will be complementary to each other and results in dna making
parts of transcription unit
promotor
gene
teeminator
what happens at promoter
dna dependent rna polymerase attaches
transcription start site
template and coding strand
template 3to5
coding 5to3
structural gene
new rna strand
gene
dna coding sequence for mRNA tRNA rRNA
criston
segment of dna coding for a polypeptide
types of structural gene
monosistronic - code 1 protien (eukaryotes)
polysistronic - code for 3 protien (prokaryotes)
exon
coding sequence that appears in matured od processed rna
introns
intervening sequences that do not appear in matured or processed rna
inheritance of a character is also affected by ___ and ___ ___ of a structural gene
promoter
regulatory sequences
regulatory sequences are also known as ___ and why
regulatory genes
it also affects inheritance of a character
types of rna required for protein synthesis
mRNA messenger - provides templates
tRNA transfer - bring AA and reads the genetic code
rRNA ribosomal - play structural & catalytic role during translation
which enzyme catalyse transcription in rna
dna dependent rna polymerase
explain the mechanism of transcription in eukaryotes
⬛rna polymerase II recognise and bind at promoter region
⬛it uncoils the dna helix and continue elongation
⬛once it reaches the terminator region the new rna falls off & the rna polymerase II
rna is synthesized in which direction
5’ to 3’
explain the mechanism of transcription in bacterias
⬛initiation - sigma factor
⬛elongation - rna polymerase
⬛ termination - rho factor
relationship btw transcription and translation in bac
They take place in the same compartment and coupled AS mrna does not require processing to become active
splicing
introns are removed and exons are joined in defined order
capping
methyl guanosine triphosphate NUCLEOTIDE is added to 5’end of hnRNA
tailing
adenylate residues (200-300) added at 3’ end
mRNA before processing OR precursor of mRNA
hnRNA - heterogeneous nuclear
function of rna polymerase I
transcribes 18s 28s 5.8s rRNA
rna polymerase II function
transcribes hnRNA
rna polymerase III function
transcribes
tRNA
5s rRNA
snRNA
