Transcription-Microbio Exam 3

When does translation begin

with DNA nucleotides 3’- TAC - 5’

What is the function of mRNA

carries the message for protein synthesis

What is the function of tRNA

carriers amino acids during protein syntheis

What is function of rRNA

molecules are components of ribosomes

Define polycitronic mRNA

contains directions for more than one polypeptide catalyzed by a single RNA polymerase for transcription in bacteria and archaea

What makes up a holoenzyme

core enzyme + sigma factor

What is the function of the sigma factor

helps the core enzyme detect the promotor, which signals the beginning of the gene

What is the sigma factor in E. coli

sigma 70

True or False: mutations in the consensus sequence can affect the strength of the promoter

True

What is the promoter region

pribknow box which contains consesus sequence (TATAAT) and sit where RNA polymerase binds to initiate transcription

When is the transcription bubble prodcuced in elongation

after RNA polymerase binds and unwinds DNA at the -10 region

True or False: during elongation the complementary and antiparellel strand is formed is DNA:DNA

False: DNA:RNA hybrid is formed

The process of DNA replication inverting upon a repeated A-rich sequence forming a hair pin loop structure is an example of what type of termination

Factor independent

What is the example of factor dependent termination

the use of rho protein binding to rut site on mRNA and unwinding the mRNA-DNA complex to release RNA polymerase through ATP hydrolysis

What are the stop and start codons

• start- AUG

• stop- UGA, UAG, and UAA

What are sense codons

61 codons tha tspecify amino acids

What is the function of the wobble (loos base pairing) between the anticodon and codon where only the 1st and 2nd position is pairing

• eliminates need for unique tRNA for each codon

• decreases effect of some mutations

What is the exception to codes seen in Mycoplasma capricolum

Stop codon UGA codes for Tryptophan

What is the exception to codes seen in Protozoan nuclei

stop codons UAA, UAG code for Glutamine