Advanced Biochemistry, Microbiology and Genetic Exam Latest Update With Question and Detailed Answer

Advanced Biochemistry, Microbiology and Genetic Exam Latest Update With Question and Detailed Answer Explain the process of rolling circle replication. - ANSWER It is a rapid unidirectional DNA synthesis of a circular DNA molecule used for the replication of some plasmids. It begins with a nicked portion of one of the 2 strands and replicates the un-nicked strand as a template. The nicked strand is eventually replaced and recircularized into a single- stranded DNA molecule and RNA primase makes a primer to initiate DNA replication and results in an identical to the other circular DNA molecule. Explain how RNA is synthesized using DNA as a template. - ANSWER Via transcription. RNA polymerase is signaled by a sigma factor to bind to a specific promoter and synthesize RNA using the antisense DNA strand as a template and adding RNA nucleotides to the 3' end of the growing strand. Distinguish between transcription in prokaryotes vs. eukaryotes. - ANSWER Prokaryotes: Initiation: begins at the promoter (TATA box) and it is typically located just upstream of the genes it encodes. Elongation: sigma factor dissociates and RNA is made from DNA in 5' to 3' direction and DNA is unwound. Termination: after the gene is transcribed, the bacterial polymerase dissociates from the DNA template and frees the new RNA. Repeated nucleotide sequences are the signals that halt and stall RNA polymerase from the DNA template which frees the RNA transcript. Eukaryotes: Has a membrane-bound nucleus which makes the process easier. mRNAs last longer to protect from degradation. Poly-A tail is a processing enzyme after elongation which signals cellular factors that the transcript needs to be exported into the cytoplasm.