-Why does E. coli have several different sigma factors?

a) they allow different RNA polymerases to bind to the promoters

b) they allow the different subunits of the RNA polymerase holoenzyme to bind to each other

c) there is no good reason, they all perform the same function

d) one is needed to transcribe mRNA. a second is needed to trasncribe tRNA. a third is needed to transcribe rRNA.

e) they allow RNA polymerase to recognize and bind to a different subset of promoters

– A segment of DNA from a fly has the sequence:

5′ TCA AGC TTA AGA AGG CAT TTT 3′

a) assuming this is the template strand, what is the sequence of the encoded mRNA?

b) if this is the coding strand, what is the sequence of the encoded mRNA?

– The sequence below is from a piece of pre-mRNA. (Sequences important for the splicing reaction are underlined.) Write the sequence of the mature mRNA.

5′ AUG UGU AGG UAA UUC UUU AUU CUU AUC UGC UUG GAA GGU UAA AGC UUC A 3′

-The following is the sequence of a piece of mRNA. Write the sequence of the double stranded piece of DNA from which it was derived. Label the strands: coding, noncoding, template, nontemplate.

5′ UCC UGA CGA UGC UAC CGA 3′