2018 Euk-Gene-Exp Organisation Control MCQ QP+MS

2018 Gene Expression, Organisation and Control MCQ 2018 / H2 / ACJC PRELIM / P1 Q101Which statement(s) about DNA polymerases and RNA polymerases is/ are correct? 1 They read the DNA template in the 3’ to 5’ direction.2 They unwind and unzip double-stranded DNA.3 They read the terminator sequence and stop adding nucleotides to nucleic acid chains.4 They bind to the same specific sequences to start their processes. A1 and 3B2 and 3 C1 onlyD4 only2018 / H2 / ACJC PRELIM / P1 Q112The following steps describe a method to study the structure and localisation of protein kinase c in yeast cells.●tRNAs with anticodon AAG were isolated and chemically modified to carry their specific fluorescent amino acids.●During translation, chemically modified amino-acyl tRNAs bind to the large ribosomal subunit.●Fluorescent amino acids are incorporated into the elongating polypeptide chain.●After translation, the polypeptide chain folds into its native conformation and the positions of the fluorescent amino acids can be detected and studied. Which of the following describes a condition which will allow the above method to be carried out?APeptidyl transferase is specific to the fluorescent amino acid and the elongating polypeptide chain in order to catalyse the formation of a peptide bond. BSynthetic amino-acyl tRNA synthetase is specific to the fluorescent amino acid and chemically modified tRNA in order to form modified amino-acyl tRNA. CThe ribosome is specific to the mRNA sequence in order to synthesise protein kinase c.DChemically modified amino-acyl tRNA is specific to the P site of a large ribosomal subunit in order to add the fluorescent amino acid to the elongating polypeptide chain.

2018 / H2 / ACJC PRELIM / P1 Q143The table shows the genome size, number of genes and chromosome number of the following organisms:OrganismGenome size (bp)Number of genesChromosome numberE.coli bacterium4 369 0004289n = 1Baker’s yeast12 069 00062002n = 32Amoeba290 000 000 000Data not available500 – 1000 (possibly polyploidy)Rodent3 399 900 000Data not available2n = 64Humans3 200 000 00030 0002n = 46From the data provided, it is possible to conclude that1 The less complex the organism, the smaller the genome size.2 Amoeba has more non-coding DNA than humans.3 The larger the genome size, the higher the number of chromosomes.4 The number of housekeeping genes is the same for all organisms. A1 and 2 B2 and 4C3 onlyD4 only2018 / H2 / ACJC PRELIM / P1 Q134In mammalian tissues, iron enter cells via transferrin receptors (TfR) and are stored when they are bound by ferritin proteins. The synthesis of TfR and ferritin is regulated through translational controls by regulatory proteins IRP1 and IRP2, which bind to iron-responsive elements (IREs) found on mRNAs. IREs are loops found at the 5’ UTR of ferritin mRNA and 3’ UTR of TfR mRNA respectively. The effects of different iron levels on IRP1 and IRP2 are shown in the figure.

Which row correctly describes the translational control of ferritin mRNA and TfR mRNA? Cellular iron (Fe) levelsFerritin levelsTfR levelsAHighHighHighBLowLowLowCHighHighLowDLowHighLow2018 / H2 / AJC PRELIM / P1 Q95The coding strand of part of a DNA molecule has the sequence 5’ GAATTA 3’. Which row is correct for this part of the corresponding template, mRNA and tRNA? the sequence of the template(non-coding DNA sequence)the sequence of the mRNA moleculethe anticodons of tRNA used in translationA5’ TAATTC 3’5’ CUUAUU 3’5’ CUU 3’ and 5’ AAU 3’B5’ TAATTC 3’5’ GAAUUA 3’5’ UAA 3’ and 5’ UUC 3’

C5’ CTTAAT 3’5’ CUUAUU 3’5’ CUU 3’ and 5’ AAU 3’D5’ CTTAAT 3’5’ GAAUUA 3’5’ UAA 3’ and 5’ UUC 3’2018 / H2 / AJC PRELIM / P1 Q136Which statement best explains how related genes involved in the same metabolic pathway are expressed together in eukaryotic cells?ARelated genes are usually located on the same chromosome so that they can be controlled by the same set of control elements. BThe same set of transcription factors may be capable of recognising the same promoter site of related genes. CThe same sets of control elements are associated with related genes so that they can be recognised by the same sets of transcription factors.DWithin the control element of related genes, the specific numbers of transcription factors binding to the control element will enable related genes to be expressed. 2018 / H2 / DHS PRELIM / P1 Q147Transfer RNA combined with an amino acid is called amino-acyl tRNA. It is possible to chemically convert the amino acid cysteine into the amino acid alanine whilst it is still attached to its tRNA.The altered amino-acyl tRNA still binds to UGU triplets on messenger RNA (mRNA), but now incorporates alanine into the resulting polypeptide instead of cysteine. Which statement is correct?AA codon on the amino-acyl tRNA determines its specificity.BBoth the amino acid and the anticodon of an amino-acyl tRNA affect where it binds to mRNA.CThe amino acid of an amino-acyl tRNA does not influence its binding to mRNA.

DThe codon-anticodon interaction is influenced by the amino acid on an amino-acyl tRNA.2018 / H2 / DHS PRELIM / P1 Q168The diagram represents some biochemical reactions involved in protein synthesis. Which of the following is correct?The molecule coded directly from DNA is represented by The bond labelled 5 is known asThe enzyme involved in catalysing bond 5 isA1 and 2 peptidepeptidyl transferaseB1 and 2peptideaminoacyl tRNA synthethaseC1, 2 and 3peptidepeptidyl transferaseD1, 2 and 4carboxylaminoacyl tRNA synthethase2018 / H2 / DHS PRELIM / P1 Q179The following statements illustrate the processes that occur during translation.

1The large subunit of the ribosome binds and forms the translation initiation complex.2The second amino acyl-tRNA complex now binds to mRNA at the “A” site of the ribosome.3The small ribosomal subunit, with initiator tRNA bound, binds to the 5’ cap of the mRNA and scans for the first start codon.4Soluble protein called release factor recognises the stop codon and binds at the “A” site. 5Formation of a peptide bond between the first and the second amino acids by peptidyl transferase.6The second amino acyl-tRNA complex moves from the “A” site to the “P” site.Which of the following shows the correct order?A3 → 1 → 2 → 5 → 6 → 4B1 → 5 → 2 → 3 → 6 → 4C3 → 5 → 2 → 1 → 4 → 6D1 → 5 → 2 → 3 → 4 → 62018 / H2 / DHS PRELIM / P1 Q2310Which best describes the correct order (from earliest to latest) in the control of gene expression in protein synthesis?APolyribosome, promoter, spliceosome, histone, primary transcriptBSpliceosome, histone, promoter, primary transcript, polyribosomeCHistone, promoter, primary transcript, spliceosome, polyribosomeDPrimary transcript, histone, spliceosome, promoter, polyribosome

2018 / H2 / EJC PRELIM / P1 Q811The electron micrograph shows part of a bacterial cell. The DNA molecule has been identified. Identify structures P and R as well as the process(es) that is/are occurring below. Structure PStructure RProcess(es)ADNA polymeraseDaughter DNADNA replicationBString of nucleosomesmRNATranscriptionCPolyribosomesPolypeptidesTranslationDPolyribosomesmRNATranscription and translation

2018 / H2 / EJC PRELIM / P1 Q912The following diagram shows the expression of a particular gene to its protein product in a eukaryotic cell. Which combination correctly describes steps 1 – 4? 1234ADNA is demethylatedAlternative splicing occursActivators bind to enhancersRibosome binds to 5’ UTRBDNA is demethylated5’ capping occursRNase does not degrade 5’ capped mRNAInitiation factors bind to ribosomeCDNA is methylatedPoly(A) tail is added to 3’ endpoly-A tail is extendedPhosphorylation of proteinDDNA is methylated5’ capping occursRemoval of 5’ capActivators bind to enhancers

2018 / H2 / JJC PRELIM / P1 Q1013Which statements concerning DNA and RNA are correct?1Adenine and guanine are bases that have a double ring structure; cytosine, thymine and uracil are bases with a single ring structure.2An adenine nucleotide from