Genetics Exam 3 – Chapter 13 MB – Flashcards

In eukaryotes, how does the length of a typical monocistronic mRNA compare to the length of the protein generated from this mRNA? There are more amino acids than mRNA bases. The number of amino acids and the number of mRNA bases are roughly the same. There are more mRNA bases than amino acids.

Which of the following statements support the previous conclusion that there are more mRNA bases than amino acids? (NOTE: While there may be some rare exceptions that don't support the conclusion, choose statements that typically support the conclusion.) Select all that apply. Each codon contains 3 RNA bases. Introns have been removed in the mRNA. The start site of transcription is upstream of the start codon. The stop codon does not code for an amino acid. The mRNA contains 5' and 3' untranslated regions. The mRNA contains a 7-methylguanosine cap. The mRNA contains a poly-A tail.

In prokaryotes, how does the length of a typical monocistronic mRNA compare to the length of the protein generated from this mRNA? There are more amino acids than mRNA bases. The number of amino acids and the number of mRNA bases are roughly the same. There are more mRNA bases than amino acids.

Which of the following statements support the previous conclusion that there are more mRNA bases than amino acids in prokaryotes? (NOTE: While there may be some rare exceptions that don't support the conclusion, choose statements that typically support the conclusion.) Select all that apply. The mRNA contains a 7-methylguanosine cap. The mRNA contains 5' and 3' untranslated regions. The stop codon does not code for an amino acid. The start site of transcription is upstream of the start codon. Introns have been removed in the mRNA. The mRNA contains a poly-A tail. Each codon contains 3 RNA bases.

Components involved in the initiation of transcription: Prokaryotic initiation of transcription

Components involved in the initiation of transcription: Eukaryotic initiation of transcription

In prokaryotes, which component must disassociate to allow for elongation of the transcriptional complex? sigma subunit rho RNA polymerase none of the above

Which statements are true? Select all that apply. Since prokaryotes lack a nucleus, translation can begin before the transcript is fully transcribed. Intrinsic termination in prokaryotes occurs when the rho termination factor interacts with the growing RNA transcript. Three different RNA polymerases in eukaryotes transcribe different classes of genes. Eukaryotic RNA polymerase II requires general transcription factors for initiation of transcription.

Which one of the following codons is recognized by this tRNA? 5' GAA 3' 5' UUC 3' 5' CTT 3' 5' TTC 3' 5' CUU 3'

The first base at the 5' end of the anticodon has relaxed base-pairing rules allowing some tRNAs to bind multiple codon sequences. This is called the third base "wobble" hypothesis. How many codons could a tRNA with the anticodon 5'-GAA-3' recognize?

Which codons are present in the UG copolymer? Select all that apply. UGG GUA TGT GUG UGU

Which codons are present in the UGG copolymer? Select all that apply. UGU UGA GGU GGT UGG GUG

The genetic code exists as _____ codons, which are sets of _____ nucleotides in which each nucleotide is one of the _____ kinds of ribonucleotides composing RNA

The complete coding dictionary reveals that of the _____ possible _____ codons, _____ encode the _____ amino acids found in proteins, while other _____ terminate translation

Transcription is the synthesis of a strand of _____ complementary to a _____ template

The processes of transcription can be subdivided into the stages of initiation, elongation, and termination. _____ of transcription is dependent on _____ region, that represents the initial binding site for _____ polymerase

The process of creating the initial transcript during transcription is more complex in eukaryotes than in prokaryotes including the addition of a _____ cap and a _____ tail, to the _____

Why doesn't polynucleotide phosphorylase (Ochoa's enzyme) synthesize RNA in vivo? In vivo polynucleotide phosphorylase is inhibited by DNA transcription factors. In vivo the concentration of ribonucleoside diphosphates is low and the degradative process is favored. RNA synthesis requires a high concentration of K+ which is usually low in vivo. There are no ribonucleoside diphosphates in vivo.

What was the initial evidence for the existence of mRNA? Select the five correct statements. The same RNA as the one found in ribosomes was involved in protein synthesis, and shortly after phage infection, an RNA species is produced that is noncomplementary to phage DNA. DNA, the genetic material, is located in the nucleus of a eukaryotic cell, whereas protein synthesis occurs in the cytoplasm. There is generally a direct correlation between the amounts of RNA and protein in a cell. Much of the RNA migrates to the cytoplasm, the site of protein synthesis. RNA, which is chemically similar to DNA, is synthesized in the nucleus of eukaryotic cells. Both DNA and protein are synthesized in the nucleus of eukaryotic cells. An RNA other than that found in ribosomes was involved in protein synthesis, and shortly after phage infection, an RNA species is produced that is complementary to phage DNA. DNA and RNA directly participate in protein synthesis.

Can you suggest a reason why this occurs? Select the two correct statements. mRNA molecules generally exist as single-stranded structures, so they are quite labile. A prokaryotic cell, which is developmentally unstable and exists in a relatively stable environment, could produce more insulin on mRNAs for a given transcriptional rate. Prokaryotic mRNAs are generally processed such that the 5' end is "capped" and the 3' end has a polyA tail, which make the mRNA more likely to be degraded. Prokaryotic cells exist in a more unstable environment than many cells of multicellular organisms, and labile mRNA is needed to accomplish such rapid responses. Nonstability of prokaryotic mRNAs probably evolved with the differentiation of nuclear and cytoplasmic functions.

Where do various forms of posttranscriptional processing in eukaryotes take place on the mRNA? Select all that apply. middle amino acid sequences 5' end internal 3' end

Considering the activities of RNAs, what might be the general functions of 3-polyadenylation? Check all that apply. regulation of introns' length regulation of mRNA proofreading regulation of mRNA longevity regulation of mRNA splicing regulation of mRNA transport to the cytoplasm regulation of mRNA association with cellular components, like proteins, lipids, or nucleic acids