Biology 1404 Exam Chapter 15-17,21 Review 2023

The AUC and AUA codons in mRNA both specify isoleucine. What feature of the genetic code explains this? - -degeneracy -How many nucleotides are in 12 mRNA codons? - -36 -Which event contradicts the central dogma of molecular biology? - -Scientists use reverse transcriptase enzymes to make DNA from RNA. -Which subunit of the E. coli polymerase confers specificity to transcription? - -σ -The -10 and -35 regions of prokaryotic promoters are called consensus sequences because ________. - -they are similar in all bacterial species -Which feature of promoters can be found in both prokaryotes and eukaryotes? - -TATA box -What transcripts will be most affected by low levels of α-amanitin? - -pre-mRNAs -How do enhancers and promoters differ? - -Enhancers increase the efficiency of gene expression, but are not essential for transcription. Promoter recognition is essential to transcription initiation. -Which pre-mRNA processing step is important for initiating translation? - -7-methylguanosine cap -What processing step enhances the stability of pre-tRNAs and pre-rRNAs? - -methylation -The RNA components of ribosomes are synthesized in the ________. - -nucleolus -In any given species, there are at least how many types of aminoacyl tRNA synthetases? - -20 -A scientist introduces a mutation that makes the 60S ribosomal subunit nonfunctional in a human cell line. What would be the predicted effect on translation? - -Translation stalls after the initiation AUG codon is identified. -Control of gene expression in eukaryotic cells occurs at which level(s)? - -epigenetic, transcriptional, post-transcriptional, translational, and post-translational levels -Post-translational control refers to: - -regulation of gene expression after translation -How does the regulation of gene expression support continued evolution of more complex organisms? - -Cells can become specialized within a multicellular organism AND Organisms can conserve energy and resources. -If glucose is absent, but so is lactose, the lac operon will be ________. - -repressed -Prokaryotic cells lack a nucleus. Therefore, the genes in prokaryotic cells are: - -transcribed and translated almost simultaneously AND