Bs21002 exam practice - Exam help PDF

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The diagram below represents the primary transcript from a eukaryotic gene and its associated mature messenger RNA. Move the blue button to lie above the 3' splice site on the primary transcript

The diagram below represents the primary transcript from a eukaryotic gene and its associated mature messenger RNA. Move the blue button to lie above the untranslated region of the second exon of the primary transcript.

The diagram below represents the primary transcript from a eukaryotic gene and its associated mature messenger RNA. Move the blue button to lie above the 5' splice site on the primary transcript

The diagram below represents the primary transcript from a eukaryotic gene and its associated mature messenger RNA. Move the blue button to lie above the untranslated region of the first exon of the primary transcript

The diagram below represents the primary transcript from a eukaryotic gene and its associated mature messenger RNA. Move the blue button to lie above the translated region of the second exon of the primary transcript.

The diagram below represents the primary transcript from a eukaryotic gene and its associated mature messenger RNA. Move the blue button to lie above the translated region of the first exon of the primary transcript.

Which of the following is a widespread feature of eukaryotic gene expression? Removal of introns from the primary transcript 5' polyadenylation of messenger RNA Palindromic transcriptional terminators Polycistronic messenger RNA Which of the following statements about Coupled transcription-translation the trp attenuator is FALSE? The trp attenuator encompasses a transcription termination sequence. The trp attenuator structure is modulated by tryptophan availability. The trp attenuator is switched into its termination configuration by stalled ribosomes. The trp attenuator has alternate base-paired structures which modulate its function. The trp attenuator encodes a short tryptophan-containing polypeptide.

The co-repressor of tryptophan biosynthesis is tRNATRP Tryptophan Tryptophan attenuator Cyclic AMP Allolactose

Which of the following would be the most likely result of a mutation in a eukaryotic organism that causes it to produce less p21 protein than normal? Cell replication would be slowed if the organism receives radiation. Cells with radiation-induced DNA damage would continue through the cell cycle without repairing the damaged DNA. Cells with incomplete DNA replication would continue through the checkpoint.

Cells would not respond to growth factors. Cells would have a hyper-sensitive response to growth factors. Drag the marker to the 3' end of the newly synthesised DNA strand

Drag the marker to the 5' end of the newly synthesised DNA strand

Microtubules that form the mitotic spindle tend to originate from or terminate in centromeres and telomeres. euchromatin. centrioles and telomeres. the nuclear envelope. centrioles and kinetochores.

Which of the following is not one of the events required for cell division? Segregation Cytokinesis Crossing over DNA replication All of the above are required for cell division.

Which of the following would be the most likely result of a mutation in a eukaryotic organism that causes it to produce less p21 protein than normal? Cell replication would be slowed if the organism receives radiation. Cells with radiation-induced DNA damage would continue through the cell cycle without repairing the damaged DNA. Cells with incomplete DNA replication would continue through the checkpoint. Cells would not respond to growth factors. Cells would have a hyper-sensitive response to growth factors. A tissue in a mouse contains two types of cells: one that divides rapidly and one that divides more slowly. The most likely difference between these two cell types is that the slow-dividing cell type spends more time in _______ phase. G1 G2 G3 M S Cyclin-dependent kinases (Cdk's) catalyze the phosphorylation of targeted proteins, a process that decreases the mass of the protein. makes the targeted proteins hydrophobic. changes the shape and function of the targeted proteins. gives the proteins a three-dimensional shape. blocks the cell cycle from proceeding. The structures that line up the chromatids on the equatorial plate during metaphase are called asters. polar and kinetochore microtubules. centrosomes. centrioles. histones. The basic structure of chromatin has sometimes been referred to as beads on a string of DNA. These "beads" are called chromosomes. chromatids. supercoils. interphases. nucleosomes. At the milestone that defines telophase, the chromosomes separate. come together. cross over. line up. are at opposite poles.

In eukaryotes, which TWO of the following features are encoded within the transcribed region of a protein-encoding gene and are still present in the mature messenger RNA? The translational initiation codon

The polyadenylation signal The 5 methyl-guanylate cap The poly-A tail The introns

Which of the following phases of the cell cycle is not part of interphase? S G0 G1 G2 M

A set of cells in the intestinal epithelium divides continually in order to replace dead cells. A microscopic examination of this population of cells would show that most of them have condensed chromatin. are in meiosis. are in mitosis. are in interphase. Both a and b

The event in the cell division process that clearly involves microfilaments is chromosome separation during anaphase. movement of chromosomes to the metaphase plate. chromosome condensation during prophase. disappearance of the nuclear envelope during prophase. cytokinesis in animal cells. Regulation of the cell cycle is dependent on cyclins and cyclin-dependent kinases. The key that allows a cell to progress beyond the restriction point is the presence of cyclin. the absence of cyclin. the presence of cyclin and Cdk. phosphorylation of RB by Cdk. the presence of external signals from growth factors. At the milestone that defines metaphase, the chromosomes separate. come together. are at opposite poles. cross over. line up at the equatorial plate.

During prokaryotic cell division, two chromosomes separate and are distributed to the daughter cells by attaching themselves to microtubules. a mitotic spindle. repellent forces. attaching themselves to separating membrane regions. Both a and b

How does a nucleus in G2 differ from a nucleus in G1? The G2 nucleus has double the amount of DNA as the G1 nucleus. DNA synthesis occurs only in G1 phase. Inactive cells are arrested only in G2 phase. During G2, the cell prepares for S phase. None of the above; there is no difference in the nucleus between G1 and G2.

Which of the following statements about meiosis and mitosis is true? DNA replication occurs only in mitosis. DNA replication occurs only in meiosis. The products of meiosis can be different from one another, while the products of mitosis are all the same (except for rare mutations). The products of mitosis can be different from one another, while the products of meiosis are all the same (except for rare mutations). Mitosis and meiosis are the same process. The microtubules of the mitotic spindle attach to a specialized structure in the centromere region of each chromosome called the kinetochore. nucleosome. equatorial plate. aster. centrosome. Replacing Arg in a histone with a neutral amino acid would make the histone _______ positively charged, and _______ likely to bind to DNA. more; more more; less less; more less; less None of the above; this replacement would have no effect because Arg is a neutral amino acid.

Which of the following is not involved in the separation of paired chromatids and their movement to opposite poles? Sister chromatids attach to microtubules in opposite halves of the spindle. Separase hydrolyzes cohesion, allowing chromatid separation. Tubulin fibers move the chromatids away from the equatorial plate. Polar microtubules push the chromatids to the poles. ATP is hydrolyzed by cytoplasmic dynein. The DNA of a eukaryotic cell is double-stranded and linear. single-stranded and linear. double-stranded and circular. single-stranded and circular. conservative.

Chromosomes contain large amounts of interacting proteins known as pentanes. hexosamines. histones. protein hormones. cyclins.

Centrosomes are constricted regions of phase chromosomes. determine the plane of cell division. are the central region of the cell. are the region where the membrane constricts during cytokinesis. are part of cilia. Chromosomes "decondense" into diffuse chromatin at the end of telophase. at the beginning of prophase. at the end of interphase. at the end of metaphase. only in dying cells. Match the status of the association of lac repressor protein and cyclic AMP receptor protein with the lac operon in E. coli to the nutrient content of the medium in which the bacterium is growing Both glucose and lactose present in the growth medium Lac repressor protein is not bound to the lac operator; Cyclic AMP receptor protein is not bound to its binding site adjacent to the lac promoter Glucose is present in the growth medium but lactose is not Lac repressor protein is bound to the lac operator; Cyclic AMP receptor protein is not bound to its binding site adjacent to the lac promoter Lactose is present in the growth medium but glucose is not Lac repressor protein is not bound to the lac operator; Cyclic AMP receptor protein is bound to its binding site adjacent to the lac promoter No glucose or lactose in the growth medium Lac repressor protein is bound to the lac operator; Cyclic AMP receptor protein is bound to its binding site adjacent to the lac promoter

Match the status of the association of lac repressor protein and cyclic AMP receptor protein with the lac operon in E. coli to the nutrient content of the medium in which the bacterium is growing. Lac repressor protein is not bound to the lac operator; Cyclic AMP receptor protein is bound to its binding site adjacent to the lac promoter Lac repressor protein is bound to the lac operator; Cyclic AMP receptor protein is not bound to its binding site adjacent to the lac promoter Lac repressor protein is not bound to the lac operator; Cyclic AMP receptor protein is not bound to its binding site adjacent to the lac promoter

Lactose is present in the growth medium but glucose is not

Lac repressor protein is bound to the lac operator; Cyclic AMP receptor protein is bound to its binding site adjacent to the lac promoter

No glucose or lactose in the growth medium

Glucose is present in the growth medium but lactose is not

Both glucose and lactose present in the growth medium

Which of the following is a widespread feature of prokaryotic gene expression?

mRNA capping 3' polyadenylation Promoter sequences Coupled transcription - translation RNA splicing

The post-transcriptional mechanism by which introns are removed from primary transcripts is called Degradation Attenuation Splicing Looping out Polyadenylation Which of the following statements is FALSE with respect to eukaryotic transcriptional initiation by RNA polymerase II? [2 marks] TFIIH is necessary for strand separation prior to transcriptional initiation by RNA Polymerase II TFIIB must associate with TFIID in order that RNA Polymerase II can be recruited to the transcription complex TFIIA prevents binding of inhibitory factors to the TFII transcription complex After the initiation of transcription, the TFIID transcription complex must dissociate from the gene promoter to allow RNA Polymerase II to proceed with transcriptional elongation TATA binding protein mediates the specific association of TFIID with the gene promoter In mitotic metaphase, a cell with eight sister chromatids has _______ centromeres. no one two four eight

Which of the following statements about mitosis is true? The chromosome number in the resulting cells is halved. DNA replication is completed in prophase. Crossing over occurs during prophase. Two genetically identical daughter cells are formed. It consists of two nuclear divisions.

Chromatin condenses to form discrete, visible chromosomes early in G1. during S. during metaphase. during prophase. at the end of cytokinesis.

Mature nerve cells, which are incapable of cell division, are most likely in

G1. the S phase. G2. mitosis. meiosis.

In plant cells, cytokinesis is accomplished by the formation of a(n) aster. membrane furrow. equatorial plate. cell plate. spindle. If a cell in G2 has 1.6 picograms (pg) of DNA, it had _______ of DNA in G1. 0.4 pg 0.8 pg 1.6 pg 3.2 pg 1.6 pg if it is a plant cell and 3.2 pg if it is an animal cell

Which of the following does not occur during mitotic prometaphase? Disappearance of the nuclear envelope Initial movement of chromosomes toward the equatorial plate Adhesion of chromatids at the centromere Synapsis of homologous chromosomes Disappearance of the nuclei

Which of the following statements about G-protein-linked receptors is TRUE? [2 marks] The ligand that binds to the extracellular domain of a G protein receptor is GTP G protein receptors must form dimers in order to activate their cytoplasmic domain and transduce the signal The ligand that binds to the extracellular domain of a G protein receptor is one of three subunits of a G protein They are all single polypeptides with 7 trans-membrane domains They are located in the cell cytoplasm rather than the plasma membrane and bind to lipid soluble ligands such as steroid hormones

At the milestone that defines anaphase, the chromosomes separate. come together. are at opposite poles. line up. cross over. Chromatin consists of DNA and histones. DNA, histones, and many other proteins. RNA and DNA. RNA, DNA, and non-histone proteins.

DNA only.

Question

15 of 30

Which of the following descriptions relating to histone acetylation in chromatin is TRUE? [2 marks] Histone deacetylases remove acetyl groups from the core histones which strengthens the DNA/histone association in the nucleosomes, thereby facilitating gene expression Acetylation of lysine residues in the N-terminal 'tails' of the core histones generally acts to relax nucleosomal structure, allowing chromatin remodelling and facilitating gene expression Histone deacetylases act upon chromatin to relax nucleosomal structure, thereby allowing chromatin remodelling and facilitating active gene expression Acetylation of lysine residues in the N-terminal 'tails' of the core histones causes the nucleosomes to coil up to form a 30 nm fibril in association with histone H1, thereby preventing gene expression Histone acetyl transferases remove acetyl groups from the core histones which strengthens the DNA/histone association in the nucleosomes, thereby inhibiting gene expression

Which of the following statements is TRUE? [2 marks] DNA methyl transferase acts to remove methyl groups from CpG islands in chromosomal DNA and promote gene expression The presence of 5-methyl cytosine in CpG islands in the regulatory region of a eukaryotic gene is often associated with gene silencing The presence of 7-methyl guanosine in CpG islands in the regulatory region of a eukaryotic gene is often associated with active gene expression The presence of 7-methyl guanosine in CpG islands in the regulatory region of a eukaryotic gene is often associated with the silencing of gene expression DNA methylase acts to remove methyl groups from CpG islands in chromosomal DNA and thereby silence gene expression

Which of the following scenarios best describes the role of the Trp attenuator under conditions of tryptophan shortage in E coli? [2 marks] In the absence of tryptophan, ribosomes are stalled at a short sequence of tryptophan codons in the attenuator, this activates the 5' to 3' exonuclease activity of the ribosomes which can then degrade the mRNA and prevent expression of the operon. In the absence of tryptophan, ribosomes are stalled at a short sequence of tryptophan codons in the attenuator and block the base pairing of a hairpin loop which would otherwise form in their absence. This in turn allows formation of an alternative hairpin loop which acts as a transcriptional terminator and aborts the transcript. In the absence of tryptophan, ribosomes are stalled at a short sequence of tryptophan codons in the attenuator and block the base pairing of a hairpin loop which would otherwise form in their absence. This in turn allows formation of an alternative hairpin loop which acts as a stop codon and aborts translation of the mRNA. In the absence of tryptophan, RNA polymerase stalls at a short sequence of tryptophan codons in the attenuator and cannot continue to transcribe the operon. In the absence of tryptophan, ribosomes associate with a short sequence of tryptophan codons at the 5' end of the template strand encoding the Trp attenuator. Their presence blocks access of RNA polymerase and prevents transcription of the operon from occurring. The energy to move chromosomes during mitosis is provided by centrioles. DNA polymerization. ATP formation of the cell plate.

None of the above; energy is not required for this action.

Which of the following statements BEST explains why E. coli does not express betagalactosidase from the lac operon when it is growing in medium containing lactose and glucose. [2 marks] In the presence of glucose, cyclic AMP receptor protein is not complexed with cyclic AMP and cannot activate transcription. The promoter of the lac operon is weak and cannot initiate transcription unless lac repressor protein can interact with RNA polymerase. The promoter of the lac operon is weak and cannot initiate transcription unless RNA polymerase is associated with sigma factor. In the presence of lactose, lac repressor protein is inactivated by association with allolactose and cannot bind to the operator. In the presence of lactose, high levels of cyclic AMP prevent cyclic AMP receptor protein from binding to the promoter and activating transcription. Which of the following statements about eukaryotic RNA polymerases is FALSE? [2 marks] RNA Polymerase II is responsible for transcribing the majority of the RNA found in a eukaryotic cell RNA Polymerase I is responsible for transcribing ribosomal RNA RNA Polymerase III is responsible for transcribing transfer RNAs RNA polymerase II is responsible for transcribing some of the RNAs involved in splicing RNA Polymerase II is responsible for transcribing all of the genes that encode proteins

The products of mitosis are one nucleus containing twice as much DNA as the parent nucleus. two genetically identical cells. four nuclei containing half as much DNA as the parent nucleus. four genetically identical nuclei. two genetically identical nuclei.

During mitosis and meiosis the chromatin compacts. Which of the following processes takes place more easily because of this compaction? The orderly distribution of genetic material to two new nuclei DNA replication Exposing of the genetic information on the DNA The unwinding of DNA from the histones The disappearance of the nuclear membrane

Which one of the following statements about the introns within eukaryotic genes is TRUE? Introns are joined together to form mature messenger RNA Introns are only found in the genes of lower eukaryotes such as Tetrahymena Introns are found in the primary transcript, but not in the mature mRNA Introns are only found in genes that are present in multiple copies, such as histone genes or

ribosomal RNA genes Introns are not transcribed, and therefore do not appear in the mature mRNA

Which item from the following list might be found in the same molecular complex as sigma factor? [2 marks] A spliceosome Aminoacyl tRNA synthetase DNA polymerase A nucleosome A prokaryotic gene promoter

In the Meselson-Stahl experiment, bacteria gr...