Why is the lagging strand synthesized in a discontinuous fashion? The lagging strand is complementary to the leading strand. DNA synthesis must occur in a 5' to 3' direction, which imposes spatial constraints on the synthesis of the lagging strand. The DNA polymerase enzyme that synthesizes the lagging strand can only synthesize short sequences of DNA before it falls off the template. The template of the lagging strand is discontinuous. All of these arc reasons why the lagging strand is synthesized in a discontinuous fashion. Indicate whether each of the following statements about the genetic code is true or false. a. The genetic code includes specific start and stop codons. T/F b. The genetic code is the same in almost all living organisms. T/F c. Deleting a single base from an mRNA molecule usually alters one codon only. T/F d. Stop codons have a dual function because each one also codes for an amino acid. T/F e. Most codons code for more than one amino acid. T/F f. Most amino acids are specified by more than one codon. T/F g. Only 20 different codons are used to code for amino acids. T/F h. In some cases, it is possible to change the sequence of bases in a codon and it will still code for the same amino acid T/F Indicate whether each of the following statements about the processing of mRNA transcripts is true or false. a. During transcript processing, noncoding regions, called exons, are removed and the coding regions, called introns, are spliced together. T/F b. The poly-A tail appears to play a role in the stability of mRNAs by protecting them from degradation. T/F
