Exam 4 Quiz 2 Flashcards
Central dogma of molecular biology
DNA transcribed into RNA and RNA translated into proteins
DNA
double stranded, deoxyribose, thyamine
RNA
single stranded, ribose, uracil
RNA polymerase
what is needed in order to make RNA
RNA polymerase charcateristics
-catalyzes the formation of phosphodiester bonds between ribonucleotides
-requires ribonucleoside triphosphates
-polymerize in 5’ to 3’ direction
-requires a template
triphosphates
where we get the energy to make RNA
5’ to 3’ means
adding to the free 3’ OH group
Template made of
made of DNA
differences with RNA polymerase
-has intrinsic helicase activity
-can initiate new strands of nucleotides on its own (NO PRIMER!! CAN start de novo)
-4-5 subunits
structure of bacterial RNA polymerase
(Alpha 2 beta beta’ omega)
+ sigma facotr
alpha 2 beta beta’ omega
core of RNA polymerase
sigma factor
helps with function
initiation of transcription begins with
finding the promoter
eukaryotes promoter
-tata box
-beta recognition element
-transcription factors to bind promoters
-small subset of bases of chromosomes transcribed
-can use either strand for replication
-oriented 5’ to 3’
bacteria promotor sites
2 sites:
-TATAAT (Pribnow box, 10 bases upstream)
-TTGACA (35 bases upstream)
-can be on either strand depending on the gene
-only one strand will be transcribed depending on orientation
strand is recognized by the…
the sigma factor
consensus sequences
doesn’t have to be exact
Elongation of transcript
-DNA template exposed
-CAN start de novo (sigma factor cues it in)
sigma factor
-leaves after transcript is initiated
-role is to get promoter recognized
-when released it can become bound to another promoter
how many sigma factors expressed in bacteria
they tend to run under the same sigma factor but can express multiple but there is usually 1 main factor