10 - Transcription

Name the three processes that commonly modify eukaryotic pre-mRNA. Select the three correct answers. 3' polyadenylation initiation termination intron splicing elongation 5' capping 5' polyadenylation 3' capping

3' polyadenylation intron splicing 5' capping

What is a gene? A gene is a structural protein that defines a heritable trait. A gene is the unit of heritage, mutation, recombination and function. A gene is a segment of DNA that contains the information for transcription of an RNA. A gene is an RNA, which codes for translation of a protein.

A gene is a segment of DNA that contains the information for transcription of an RNA

Which of the following is most likely attributable to a base substitution at a 5' splice junction? A longer than usual final transcript An amino acid substitution in the final protein product Failure of the U2 snRNP to bind the transcript A shorter than usual final transcript

A longer than usual final transcript

Which of the following statements about eukaryotic transcription is false? The transcripts produced contain both exons and introns. Transcription initiation occurs when RNA polymerase binds to a complex of transcription factors at the TATA box. A polycistronic mRNA may be transcribed if the gene products are used in the same pathway or needed at the same time. Eukaryotic promoter regions contain a TATA box and a CAAT box.

A polycistronic mRNA may be transcribed if the gene products are used in the same pathway or needed at the same time

A DNA sequence produces a mutant protein in which several amino acids in the middle of the protein differ from the normal protein. What kind of mutation could have occurred? A nonsense mutation No mutation An addition and a deletion mutation An addition or deletion mutation

An addition and a deletion mutation

Speculate about why enhancers are not part of transcription of bacterial genes. Select the three correct answers. Bacteria mostly regulate gene expression at the level of translation, making transcription enhancers unnecessary. Bacterial operons make coordinate regulation of protein synthesis by enhancers unnecessary. There is little to no intergenic space on bacterial chromosomes, which makes long-range-acting enhancer sequences unnecessary. Enhancers often provide a mechanism for cell-specific transcription of genes, and most bacteria lack differentiated cell types. The high level of mutation in bacterial genomes would likely alter these conservative sequences rendering them nonfunctional.

Bacterial operons make coordinate regulation of protein synthesis by enhancers unnecessary. There is little to no intergenic space on bacterial chromosomes, which makes long-range-acting enhancer sequences unnecessary. Enhancers often provide a mechanism for cell-specific transcription of genes, and most bacteria lack differentiated cell types.

What is the role of DNase I? DNase cuts the DNA molecule wherever it can bind to it and it can cut the DNA molecule in regions where other proteins are bound. DNase cuts the DNA molecule wherever it can bind to it, but it cannot cut the DNA molecule in regions where other proteins are bound. DNase represses transcription of DNA wherever it can bind to it, and it can cut the DNA molecule only in regions where other proteins are bound. DNase enhances transcription of DNA wherever it can bind to it, and it can cut the DNA molecule only in regions where other proteins are bound.

DNase cuts the DNA molecule wherever it can bind to it, but it cannot cut the DNA molecule in regions where other proteins are bound

What is the role of enhancer sequences in transcription of eukaryotic genes? Select the three correct answers. Enhancers increase the level of transcription of genes in an orientation independent manner. Enhancers bind transcription factors that stimulate transcription of one or more genes. Enhancers increase the level of transcription of genes in a position independent manner. Enhancers act as alternative promoter sequences that increase the rate of transcription.

Enhancers increase the level of transcription of genes in an orientation independent manner. Enhancers bind transcription factors that stimulate transcription of one or more genes. Enhancers increase the level of transcription of genes in a position independent manner.

Which of the following is characteristic of transcription in eukaryotes but not in prokaryotes? Exon splicing catalyzed by the spliceosome A 5' untranslated leader sequence A 3' untranslated trailer sequence A single transcript may be transcribed and translated simultaneously.

Exon splicing catalyzed by the spliceosome

Which of the following is a characteristic of RNA splicing in Eukaryotes? It involves recognition of sequence-specific intron/exon boundary sites by cytoplasmic proteins. After splicing occurs, the U1, U2, U5, U6 snRNP complex removes remaining exons for degradation. Exon/intron boundaries are typically characterized by a 5' GU splice junction and a 3' AG splice junction. It involves removal of introns from a gene sequence followed by transcription and subsequent splicing of exons.

Exon/intron boundaries are typically characterized by a 5' GU splice junction and a 3' AG splice junction

The genetic code is degenerate, meaning that a codon can specify more than one amino acid. True or False?

False

Prokaryotes have a -10 and -35 consensus sequence in their promoter. What are the three eukaryotic promoter sequences elements (or "boxes")? TAAC GC-rich CAAT TATA CATA OCT AT-rich

GC-rich CAAT TATA

There are two main types of RNA editing: substitution editing and insertion/deletion editing. Which of the following statements are true about these types of editing? Select all that apply. Insertion of uracil can be directed by guide RNA (gRNA). Insertion/deletion editing adds or subtracts nucleotides from the total number of bases. Substitution editing can result in proteins that function differently in their respective cell types. Substitution editing changes individual nucleotides via chemical modification.

Insertion of uracil can be directed by guide RNA (gRNA). Insertion/deletion editing adds or subtracts nucleotides from the total number of bases. Substitution editing can result in proteins that function differently in their respective cell types. Substitution editing changes individual nucleotides via chemical modification.

What are the mechanisms for transcription termination in bacteria? Select all that apply. intrinsic rho-dependent closed alternative interfering opened

Intrinsic rho-dependent

s coupling of transcription and translation possible in single-celled eukaryotes such as yeast? Why or why not? No, because yeast chromosomes are separated from ribosomes by the nuclear envelope and some of their genes contain introns. Yes, because yeast genes do not contain introns that makes pre-mRNAmRNA splicing unnecessary.

No, because yeast chromosomes are separated from ribosomes by the nuclear envelope and some of their genes contain introns

What are two distinguishing features of RNA? RNA contains a pyrophosphate group bound to the ribose. RNA has a ribose sugar and uracil nitrogenous base. RNA contains a methylated form of thymine. RNA contains phophodiester bonds as part of its sugar backbone. RNA forms a double helix of reverse complementary strands.

RNA has a ribose sugar and uracil nitrogenous base

What must eukaryotes do to initiate transcription of a gene? Bind RNA Polymerase to displace histone proteins that binding DNA in the promoter region. Bind transcription factors from enhancer sequences to the RNA Polymerase. Recruit the transcription factors and RNA Polymerase that compose the pre-initiation complex. Recruit general transcription factors to produce an open complex and then recruit RNA Polymerase. Open the DNA template and then bind RNA Polymerase at the transcriptional initiation site.

Recruit the transcription factors and RNA Polymerase that compose the pre-initiation complex

A gene has acquired a mutation in which the protein product has 50 additional amino acids at the end. Which region of the gene was likely mutated? terminator sequence promoter sequence start codon coding region stop codon

Stop codon

What is the function of the sigma subunit in bacterial RNA polymerase? Recognition of the transcriptional termination sequence Elongation of the RNA during synthesis Binding to the template DNA strand The sigma subunit induces a conformational change in the RNA polymerase core enzyme that switches it to its active form.

The sigma subunit induces a conformational change in the RNA polymerase core enzyme that switches it to its active form

Which of the following best describe(s) the function of the 5' mRNA cap? Check all that apply. Termination of transcription To provide a binding site for poly(A) polymerase To protect the transcript from degradation It provides a site for ribosome binding in the cytoplasm.

To protect the transcript from degradation It provides a site for ribosome binding in the cytoplasm

Which of the following lists steps of mRNA production in eukaryotes in the correct order? Transcription, addition of poly-A tail, 5' cap addition, exon splicing, passage through nuclear membrane Transcription, 5' cap addition, addition of poly-A tail, exon splicing, passage through nuclear membrane Transcription, 5' cap addition, addition of poly-A tail, passage through nuclear membrane, exon splicing 5' cap addition, addition of poly-A tail, exon splicing, passage through nuclear membrane, transcription

Transcription, 5' cap addition, addition of poly-A tail, exon splicing, passage through nuclear membrane

How is coupling of transcription and translation possible in bacteria? Select all that apply. the primary transcript without the complete open reading frame bacterial transcripts do not contain introns there are membranes separating the chromosome from ribosomes bacterial ribosomes cannot translate the mRNA without pre-mRNA splicing as soon as an mRNA is transcribed, ribosomal subunits have physical access to it

bacterial transcripts do not contain introns as soon as an mRNA is transcribed, ribosomal subunits have physical access to it

Why are genes for rRNA and tRNA considered to be genes even though they do not produce polypeptides? The structures of tRNA and rRNA are similar to the structures of polypeptides. The functions of rRNA and tRNA are similar to the functions of polypeptides. rRNA and tRNA are also gene products along with polypeptides. The statement is false; DNA sequences encoding for rRNA and tRNA are not actually genes.

rRNA and tRNA are also gene products along with polypeptides

What proteins bind to silencer sequences, forming a protein "bridge" that bends the DNA over the promoter and prevents transcription? transcriptional proteins repressor proteins activator proteins rho proteins

repressor proteins

What are catalytically active RNAs that can activate processes such as self-splicing? snRNAs rnzymes ribosomes pre-mRNAs ribozymes

ribozymes

A snRNP is best described as _______. short mRNA transcripts combined with nuclear protein complexes a specific sequence of 7 bases in the mRNA transcript small RNAs associated with protein complexes in the nucleus the loop structure that forms when two exons are brought into close proximity

small RNAs associated with protein complexes in the nucleus

Which three types of RNAs are found in both prokaryotes and eukaryotes? Select the three types. snRNA tRNA pre-mRNA mRNA siRNA miRNA rRNA

tRNA mRNA rRNA

Which of the following are classified as functional or structural RNAs? mRNAs, tRNAs, and rRNAs mRNAs and tRNAs Only mRNAs tRNAs, rRNAs, and snRNAs

tRNAs, rRNAs, and snRNAs

In a given bacterium, transcription of housekeeping genes is normal, but genes involved in nitrogen metabolism, stress, and chemotaxis are disrupted. Which sigma subunit is INTACT? σ32 σ35 σ28 σ54 σ70

σ70