Question

A) Explain lagging strand DNA replication in detail. Underline the following terms in your answer: replication fork, DNA polymerase III, primase, and ligation. Make sure that your answer is complete and that all the entities that come together in the process of lagging strand replication are clearly explained. Draw one figure of a replication fork with the polarity (directionality) of each DNA strand indicated.

G) Explain RNA transcription in E. coli in detail, from initiation to termination. Underline the following terms in your answer: promoter, core enzyme, ribonucleotides, and

sigma factor. Make sure that your answer is complete and that all the entities that come together in the process of RNA transcription are clearly explained. Include one figure

illustrating transcription in action with all components, including nucleotide strand polarity, clearly labeled.

C)Compare and contrast translation initiation in prokaryotes and eukaryotes. Underline the following terms in your answer: Shine-Dalgarno sequence, peptidyl site (P-site), initiation factors, large ribosomal subunit. Make sure your answer is complete and that all of the entities involved in translation initiation are clearly explained. Draw one figure of a prokaryotic OR eukaryotic translation initiation complex with all components labeled. Be sure to indicate whether it is a prokaryotic or eukaryotic initiation complex.

T) Describe the process of translation elongation in detail. Underline the following terms in your answer: aminoacyl - tRNA synthetase, elongation factor, anticodon, peptidyl transferase. Make sure your answer is complete and that all of the entities involved in translation elongation are clearly explained. Draw one figure of an mRNA and ribosome engaged in translation with all of the components labeled.

Answer 1

There are two strands of DNA found at the replication fork, one is called the leading strand which is replicated continuously in 3' to 5' directions while the other strand called the lagging strand is replicated discontinuously in short fragments called Okazaki fragments. The replication of the lagging strand is more complicated than that of the leading strand due to its orientation.

The complete steps of the lagging strand DNA replication are as follows:

a) The ds DNA is opened/unzipped by the enzyme helicase thus resulting in a fork-like structure. Then the enzyme primase generates short RNA strands which bind to the ssDNA with help of the enzyme DNA polymerase III. Thus, DNA synthesis starts. The leading strand is replicated in 5' to 3' direction continuously while the lagging strand replication is discontinuous with the formation of short Okazaki fragments whose ligation is done by the enzyme DNA ligase .