Mutant N. crassa cells that cannot make arginine on their own must be supplied with arginine to grow. For the metabolic pathway shown in Figure 16.1, if a mutant lacked enzyme 2, would it still be able to grow if it were provided with (a) ornithine or (b) citrulline in its diet?
[a] No [b] yes
According to the original central dogma, what macromolecule or phenomenon is directly responsible for an organism's phenotype?
Each codon shown below specifies an amino acid. For which one is it possible that a change in a single base could create a stop codon?
Consider the consequences of a mutation in the DNA template sequence 5'ATG3' to 5'TTG3': What is (a) the resulting change in the mRNA codon and (b) the effect on the corresponding amino acid?
a) CAU to CAA; (b) His to Gln
When an amino acid is specified by more than one codon, what is usually shared by the set of codons that specify this amino acid?
the first and second bases
A point mutation that results in the substitution of one amino acid for another within a protein is a ______.
why some changes in DNA sequence do not change the corresponding protein?
The genetic code is redundant.
During transcription, in which direction is (1) RNA synthesized and in which direction is (2) the DNA template "read"?
(1) 5'—>3' (2) 3'—>5'
Why are ribonucleoside triphosphates the monomers required for RNA synthesis rather than ribonucleoside monophosphates?
Ribonucleoside triphosphates have high potential energy, making the polymerization reaction exergonic.
How is a mutation in a bacterial cell that deletes three base pairs 10 base pairs upstream from the +1 site likely to affect transcription and why?
Initiation will be inhibited because sigma cannot bind to the promoter.
Which statement is most accurate concerning the function(s) of the 5' cap and the 3' poly(A) tail of eukaryotic mRNAs?
Both structures are important for initiating translation and extending the lifespan of the mRNA.
What is recognized by an aminoacyl tRNA synthetase?
one amino acid and the set of tRNAs that are coupled to that amino acid
During the elongation phase of translation, individual tRNAs move through the three sites of the ribosome in the following sequence _____.
How does the bacterial ribosome recognize where to start translation?
The small ribosomal subunit binds to a sequence in the mRNA just upstream of the start codon