Ch. 12 Bio

25 July 2022
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During the process of transcription in a eukaryote
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RNA polymerase synthesizes new nucleotide chains in the 5' to 3' direction.
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Which of the following best describes transcription
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DNA -> RNA
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Which of the following best describes translation?
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RNA -> Protein
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The amino acid sequence of a protein determines its shape and specific function. TRUE OR FALSE?
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True
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At what point in gene expression do molecules go from being information storage molecules to metabolic and structurally functional molecules?
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When RNA is translated into protein
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There is an error during the transcription of a gene, what will be the consequence?
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The final protein might not be functional
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There is an error during translation of a gene, what will be the consequence?
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The protein might not be functional
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The segment of the DNA molecule where messenger RNA synthesis begins is called the
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promoter region
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The complimentary messenger RNA strand that would be synthesized from the DNA base sequence of 5' CTGAC 3' would be
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3' GACUG 5'
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The structure that causes the synthesis of RNA to cease is known as the
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transcription terminator
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What is a difference between DNA replication and RNA transcription?
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In DNA replication the helix is never closed after it is opened by helicase, but once RNA polymerase has finished transcribing a region the double helix closes
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How do you know that the gene being transcribed in the animation is a prokaryote?
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The initiation of transcription involves a sigma factor
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The enzyme that accomplishes transcription is termed
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RNA polymerase.
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The transcription enzyme first attaches to the ________ of the gene. The transcription enzyme first attaches to the ________ of the gene.
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promoter
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RNA polymerase is able to open the DNA double helix as it moves down the template. What type of enzymatic activity does this mean RNA polymerase must possess? Polymerase activity
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Helicase activity
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Which of the following statements about structural gene is TRUE?
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Transcription of structural genes requires DNA sequences that are not part of the gene itself
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Why are nucleotide triphosphates used to polymerize RNA?
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The triphosphate is a high energy molecule so that polymerization is spontaneous
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The terminator of a gene is located upstream of the coding region. TRUE or FALSE
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False
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Which of the following statement(s) about basal transcription factors is(are) TRUE?
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they are essential for transcription and they cannot increase the rate of transcription by themselves
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The assembly of transcription factors begins
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upstream from the transcription start site.
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A large region of a promoter has been deleted upstream of a gene. What effect will this have on transcription of the gene?
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Basal transcription factors won't bind to the template DNA, so RNA polymerase will not bind to the template DNA, so transcription will not occur
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If a protein in the coactivator complex does not function properly, what would be a consequence?
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Activators and repressors will not be able to properly effect the rate of transcription
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Evaluate the statements below and determine which is the best reason for why eukaryotes use basal transcription factors?
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They give the cell tight control over transcription
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Eukaryotic transcription factors include activators and coactivators. True or False
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True
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The Rho protein is involved in the _____ stage of transcription
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termination
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Which of the following is correct regarding sigma factor?
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it recognizes the promoter region
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Which of the following occurs first in transcription?
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formation of a holoenzyme
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What would happen if the sigma factor didn't bind to the RNA polymerase?
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RNA polymerase would not bind to the template DNA
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If the rho protein did not bind to the RNA, what might be the consequence?
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The RNA polymerase would not dissociate from the RNA and the template DNA
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Bicyclomycin is an antibiotic that is effective against many gram negative bacteria. It works by inhibiting Rho. What direct effect would this have on a bacteria?
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It would prevent termination of RNA transcription, causing mRNA transcripts to be abnormally long.
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Splicing joins together
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two exons
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The snRNPs are also called
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snurps.
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Arrange the following in the proper sequence in which they occur during RNA splicing. 1. Lariat is formed 2. U2 binds to branch site 3. 3' splice site is cut
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2, 1, 3
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Study the RNA sequence below and determine where the boundaries of an intron could be. Select the answer that includes the entire intron in red.
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5' ...CCGAGGUACGAUUUGAGUCGGCUACAGUAUUGA.... 3'
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Introns are generally considered 'free to mutate,' meaning that if a mutation occurs within the intron, it will not effect the functional protein. What is an exception to this axiom?
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If there is a mutation in the 3' or 5' splice site, the snurp won't recognize it, and it will not be removed from the mRNA
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Which of the following do snRNPs bind to?
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5' and 3' ends of the intron
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Which of the following statements about RNA splicing is FALSE?
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all of these choices are true
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Translation is the synthesis of
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proteins from mRNA.
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Which of the following occurs as the ribosome shifts down the mRNA by a distance of three nucleotides?
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the tRNA that was in the P site moves into the E site
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Translation is terminated when a stop codon is presented at the ________ site.
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A
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The formation of a bond between the peptide in the P site and the amino acid in the A site
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The formation of a bond between the peptide in the P site and the amino acid in the A site
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A mutation occurred in the third codon position of a gene, but the protein still functions normally. How is this possible?
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The genetic code is redundant, so that mutations in the third position of the codon often result in the same amino acid being specified.
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Why is RNA synthesis called 'transcription' and protein synthesis called 'translation?'
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RNA synthesis makes a complementary copy of the DNA using nucleic acid and protein synthesis requires the information in the RNA to be changed into a different type of molecule
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Which of the following statements about eukaryotic mRNA is TRUE?
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a cap is added to their 5' end, a poly-A tail is added to their 3' end, and each usually specifies only a single protein
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Which of these events occur as a prokaryotic mRNA is being transcribed?
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translation of protein
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Why do eukaryotes require a 5' cap and a poly-A tail but prokaryotes don't?
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Prokaryotes don't need to transport their RNA out of the nucleus, so they don't need these features
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What changes would a scientist want to make to a eukaryotic gene before they insert it into a bacterial chromosome to be expressed?
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They should remove the introns
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Which of the following is not involved in the initiation of translation?
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mRNA
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The Shine-Dalgarno sequence is found on the ________.
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mRNA
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Why is GTP used during the initiation of translation?
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To facilitate the binding of the mRNA, and the initiator tRNA to the ribosome
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All nascent proteins being with what amino acid?
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Methionine
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If the Shine-Delgarno sequence was mutated, what might be a consequence?
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The mRNA would not bind to the small ribosomal subunit in the proper location
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During translation elongation, amino acids are brought to the ribosome with the help of
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EF-Tu
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Which of the following occurs as a result of translocation?
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the tRNA that was in the P site moves into the E site
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Which of the following statements about peptidyl transferase is TRUE?
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It catalyzes the formation of peptide bonds and It is present in the 50S ribosomal subunits.
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How does the ribosome recognize the proper tRNA to bind?
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Only a tRNA with an anticodon that is complementary to the codon will bind in the A-site
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How is GTP used during elongation?
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It aids in the binding of the incoming tRNA to the A site of the ribosome AND It aids in translocating the ribosome one codon down the mRNA
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Translation is terminated when a stop codon is presented at the
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A site.
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The protein that promotes translation termination is called
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release factor
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Which of the following statements about termination is TRUE?
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No tRNA can recognize a stop codon. It is recognized by a release factor protein.
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A single point mutation has occurred in a gene causing a stop codon to appear early in the translation of the protein. What effect will this have on the protein?
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The early stop codon will cause termination to occur earlier, and the protein will be abnormally short.
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Which part of the protein is formed during termination?
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Free carboxylic acid group
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The initiating transfer RNA, carrying formylmethionine, binds to which site?
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P site
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The amino acids carried by the transfer RNA are joined by
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peptide bonds.
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The three base sequence on the transfer RNA is the codon. True or False
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False
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New amino acids (other than the initial f-Met) enter at which site?
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A
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At the E site
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transfer RNA is released
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What is unusual about the initiator tRNA?
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It carries a modified amino acid
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What stimulates the ribosome to move down one codon?
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The formation of a bond between the peptide in the P site and the amino acid in the A site
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If an aminoacyl-tRNA synthetase added the wrong amino acid to a tRNA, what would happen?
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The tRNA would carry the worng amino acid, and it would be incorporated into the growing protein
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The molecule that contains the genetic information for the production of a structural gene.
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mRNA
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The synthesis of an RNA copy of a gene
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Transcripton
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The synthesis of a specific sequence of amino acids on a ribosome.
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Translation
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A molecule found in the nucleus of cell that contains the cell's genome
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DNA
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A molecule made of amino acids that correspond to the genetic information in a structural gene
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Polypeptide
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During the process of translation in a eukaryote
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mRNA interacts with ribosomes in the cytoplasm.
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List events of transcription
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Rna Polymerease binds to promoter>DNA is unwound, RNA is synthesized in the 5'->3' >RNA polymerase reaches the > The new mRNA is released.
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tRNAs and rRNAs transcribes what genes?
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RNA polymerase 1 and 2
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protein coding transcribes what gene(s)
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RNA polymerase 2
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The genetic code is degenerate. That means
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a particular amino acid can be specified by more than one codon.
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The genetic code consists of ____ codons that specify amino acids, and ____ codons that do not specify amino acids.
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61/3
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There is only one start codon, AUG. This means that
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all newly-made polypeptides have a methionine at their amino end.
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Structural RNA that lnks an amino acid to an antcodon
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tRNA
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Contains information to be translated (as codons)
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mRNA & Genes
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Forms part of the enzyme that drives translation
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Ribosomal RNA & Ribosomal protein
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In eukaryotes, transcription to produce an mRNA must occur in
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the nucleus, where the chromosomal DNA is found
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A 5'-CUA-3' codon in an mRNA could be recognized by which of the following anticodon sequences in a tRNA?
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3'-GAU-5'
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The reason that the genetic code can correctly specify the order of amino acids in a polypeptide is
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specific tRNAs become attached to specific amino acids.
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A characteristic shared by eukaryotic mRNA, tRNA, and ribosomal RNA is that...
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they are all transcribed from DNA
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A difference between bacterial and eukaryotic transcription
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in eukaryotes, there are different RNA polymerases (I, II, and III).
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A difference between bacterial and eukaryotic translation is
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modifications to the 5' end of mRNA help it to bind to ribosomes only in eukaryotes
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Which of the following does not occur during the processing of eukaryotic mRNA?
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a ribosome recognition sequence is added
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RNA processing does NOT involve which of the following?
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Removal of exons
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What is the difference in the DNA sequence of the normal individual and that of the individual with sickle cell anemia?
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A single base has been changed
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What is the difference in the amino acid sequence (and therefore the protein) of the normal individual and that of the individual with sickle cell anemia?
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A single amino acid has been changed
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Look at the sequence of DNA in the normal and diseased individual. Using the Genetic Code, determine which amino acid has replaced which?
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Glutamic acid has switched to aspartic acid
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Using Table 3.14, characterize the amino acids that have been substituted in the normal and mutant proteins, glutamic acid to valine.
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Glutamic acid is acidic and polar, valine in nonpolar
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Which of the following statements below is TRUE? (?1)
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A single point mutation in the DNA sequence leads to a change in the protein structure, which leads to a change in the protein's function and causes sickle cell anemia
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Which of the following statements below is TRUE? (?2)
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A complex disease like sickle cell anemia is due to the substitution of a single amino acid in a single protein