Suppressor Mutations Quiz
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Questions and Answers

What is the term for a mutation that hides or suppresses the effect of another mutation?

  • Interfering mutation
  • Transposable mutation
  • Intragenic mutation
  • Suppressor mutation (correct)

    • What type of mutation restores the wild-type gene and phenotype?

  • Suppressor mutation
  • Reverse mutation (correct)
  • Interfering mutation
  • Forward mutation

    • What are the sequences that can move about the genome called?

  • Flanking directed repeats
  • Transposable elements (correct)
  • Terminal inverted repeats
  • Interfering elements

    • What is the name for the second mutation in a different gene that fixes the problem caused by the first mutation?

    <p>Intergenic mutation</p> Signup and view all the answers

    What is the term for a mutation that hides or suppresses the effect of another mutation?

    <p>Suppressor mutation</p> Signup and view all the answers

    What is the term for the second mutation in the same gene that 'fixes' the problem caused by the first mutation?

    <p>Intragenic mutation</p> Signup and view all the answers

    What are the sequences that can move about the genome called?

    <p>Transposable elements</p> Signup and view all the answers

    What is the movement of transposons called?

    <p>Transposition</p> Signup and view all the answers

    What is the name of the enzyme responsible for cutting out the transposon and separating it?

    <p>Transposase</p> Signup and view all the answers

    What is the term for the sequences of 9-40 base pairs in length that are inverted complements of each other?

    <p>Terminal inverted repeats</p> Signup and view all the answers

    How are flanking direct repeats generated during the transposition process?

    <p>Cutting and leaving overlapping ends</p> Signup and view all the answers

    What type of chromosomal rearrangement is caused by pairing through looping and crossing over between two transposable elements oriented in the same direction?

    <p>Deletion</p> Signup and view all the answers

    What type of chromosomal rearrangement is caused by pairing through bending and crossing over between two transposable elements oriented in opposite directions?

    <p>Inversion</p> Signup and view all the answers

    What type of chromosomal rearrangement results from misalignment and unequal exchange between transposable elements located on sister chromatids?

    <p>Deletion and duplication</p> Signup and view all the answers

    Which type of transposon in bacteria is characterized by genetic material flanked by two insertion sequence elements?

    <p>Composite transposons</p> Signup and view all the answers

    What is the name of the specific transposable element in eukaryotes that is similar to transposable elements in bacteria and contains short inverted repeats?

    <p>DNA transposons</p> Signup and view all the answers

    Which bacterial gene insertion can be used as a marker for testing bacterial gene insertions?

    <p>Tetracycline resistance</p> Signup and view all the answers

    What is the enzyme responsible for copying the ssRNA genome into DNA in retrotransposons?

    <p>Reverse transcriptase</p> Signup and view all the answers

    What happens to retrotransposons lacking a functional coat protein gene?

    <p>They are stuck inside the cell</p> Signup and view all the answers

    What kind of events are some transposition events linked to?

    <p>Adaptive change</p> Signup and view all the answers

    What is the role of mutations in creating variety and evolution?

    <p>They create variety necessary for evolution</p> Signup and view all the answers

    Which proteins regulate transcription of a gene by binding to a regulatory element that controls that gene?

    <p>Helix-turn-helix</p> Signup and view all the answers

    What do regulatory genes encode that interact with other sequences and affect the transcription and translation of these sequences?

    <p>Transcription factors</p> Signup and view all the answers

    What are DNA sequences that play a role in regulating gene expression, often by binding sites for transcription factors?

    <p>Regulatory elements</p> Signup and view all the answers

    What are DNA sequences that play a role in regulating gene expression, often by binding sites for transcription factors?

    <p>Regulatory elements</p> Signup and view all the answers

    Which proteins regulate transcription of a gene by binding to a regulatory element that controls that gene?

    <p>DNA binding proteins</p> Signup and view all the answers

    What type of chromosomal rearrangement is caused by pairing through looping and crossing over between two transposable elements oriented in the same direction?

    <p>Tandem duplication</p> Signup and view all the answers

    What is the function of a regulator gene in an operon structure?

    <p>It encodes products that affect the operon function, but are not part of the operon</p> Signup and view all the answers

    What is the role of a separate regulator gene in an operon structure?

    <p>It encodes a regulator protein that may bind to the operator site to regulate the transcription of mRNA</p> Signup and view all the answers

    What is the defining feature of an operon structure?

    <p>Set of co-expressed genes controlled by the same regulatory elements</p> Signup and view all the answers

    What is the defining feature of an inducible operon?

    <p>It requires a small molecule to turn the gene on</p> Signup and view all the answers

    What is the characteristic of a negative repressible operon?

    <p>It requires a small molecule to turn the gene off</p> Signup and view all the answers

    What is the role of a positive operon?

    <p>It involves protein binding to DNA to turn the gene on</p> Signup and view all the answers

    What type of operon example does the lac operon exhibit?

    <p>Negative inducible operon</p> Signup and view all the answers

    What is the regulatory element controlling the lac operon?

    <p>Inducer- allolactose</p> Signup and view all the answers

    In what conditions does the lac operon function in relation to glucose availability?

    <p>When glucose isn’t available</p> Signup and view all the answers

    What is the role of allolactose in the lac operon?

    <p>It binds to the regulator protein, making it inactive</p> Signup and view all the answers

    What happens in the absence of lactose in the lac operon?

    <p>The repressor protein binds to the operator, inhibiting transcription</p> Signup and view all the answers

    What is the function of the enzyme B-galactosidase in the lac operon?

    <p>It breaks lactose into galactose and glucose</p> Signup and view all the answers

    What is the function of the regulator protein in the lac operon?

    <p>It binds to the operator in the absence of lactose, inhibiting transcription</p> Signup and view all the answers

    What is the function of the enzyme B-galactosidase in the lac operon?

    <p>It breaks lactose into galactose and glucose</p> Signup and view all the answers

    What is the role of allolactose in the lac operon?

    <p>It binds to the regulator protein and makes it inactive</p> Signup and view all the answers

    What happens in the absence of lactose in the lac operon?

    <p>The regulator protein binds to the operator and inhibits transcription</p> Signup and view all the answers

    What is the defining feature of a negative repressible operon?

    <p>It is usually on and binding of a corepressor inhibits transcription</p> Signup and view all the answers

    What type of regulation is the lac operon an example of?

    <p>Positive inducible regulation</p> Signup and view all the answers

    What prevents the binding of catabolite activator protein (CAP) to the lac operon in the presence of glucose?

    <p>Glucose inhibits the production of cAMP</p> Signup and view all the answers

    What type of operon is the trp operon of E. coli?

    <p>Negative repressible operon</p> Signup and view all the answers

    What is the defining characteristic of euchromatin?

    <p>Uniform structure</p> Signup and view all the answers

    How are structural genes transcribed in eukaryotes?

    <p>Each gene has its own promoter and is transcribed separately</p> Signup and view all the answers

    What is the role of histone proteins in transcription?

    <p>Prevent transcription by tightly binding to DNA</p> Signup and view all the answers

    Where does the process of translation occur in eukaryotic cells?

    <p>In the cytoplasm</p> Signup and view all the answers

    What is the role of histone acetylation in gene expression?

    <p>It weakens the interaction between histone proteins and DNA, allowing transcription factors to activate gene expression</p> Signup and view all the answers

    How does histone methylation typically affect gene expression?

    <p>It often causes gene silencing by repressing transcription</p> Signup and view all the answers

    What is the function of histone modification through addition of acetyl groups?

    <p>It typically causes relaxation of chromatin, allowing for gene expression</p> Signup and view all the answers

    How is gene expression controlled in Arabidopsis through histone acetylation?

    <p>Histone acetylation allows transcription factors to activate gene expression</p> Signup and view all the answers

    How is DNA methylation maintained through replication?

    <p>The DNA is hemi-methylated and methyl groups are added to the unmethylated strand, resulting in fully methylated DNA</p> Signup and view all the answers

    What is the effect of histone acetylation on the interaction between histone proteins and DNA?

    <p>It weakens the interaction, permitting some transcription factors to bind to DNA</p> Signup and view all the answers

    What is the function of an insulator in gene regulation?

    <p>It blocks or insulates the effect on enhancers</p> Signup and view all the answers

    What is the role of a silencer in gene regulation?

    <p>It is a site where repressor proteins bind</p> Signup and view all the answers

    What is the function of an enhancer in gene regulation?

    <p>It is a DNA sequence stimulating transcription from a distance away from the promoter</p> Signup and view all the answers

    What are response elements in gene regulation?

    <p>Common regulatory elements upstream of the start site of genes expressed in response to a common environmental stimulus</p> Signup and view all the answers

    What is the role of microRNAs in gene expression regulation?

    <p>MicroRNAs inhibit translation by pairing imperfectly with mRNA sequences</p> Signup and view all the answers

    What is the function of small interfering RNAs (siRNAs) in gene expression regulation?

    <p>SiRNAs combine with protein complex RISC and pair with complementary sequences on mRNA to degrade RNA</p> Signup and view all the answers

    How does RNA interference (RNAi) influence transcription of DNA?

    <p>SiRNAs attach to complementary sequences in DNA and attract methylating enzymes which methylate the DNA or histones and inhibit transcription</p> Signup and view all the answers

    What is the role of dicer in RNA cleavage?

    <p>Dicer cleaves double-stranded RNA to produce small interfering RNAs and microRNAs</p> Signup and view all the answers

    What is the outcome of microRNAs pairing imperfectly with an mRNA sequence?

    <p>Inhibition of translation</p> Signup and view all the answers

    How do some siRNAs influence transcription of DNA?

    <p>Attach to complementary sequences in DNA and attract methylating enzymes, leading to methylation of DNA or histones</p> Signup and view all the answers

    What is the defining characteristic of a benign tumor?

    <p>Tumor remains localized</p> Signup and view all the answers

    What is the function of the G0 phase in the cell cycle?

    <p>The cell enters a non-dividing phase</p> Signup and view all the answers

    What occurs during the S phase of the cell cycle?

    <p>DNA duplicates</p> Signup and view all the answers

    What happens at the G2/M checkpoint in the cell cycle?

    <p>The cell prepares for mitosis</p> Signup and view all the answers

    What is the role of cyclins in the cell cycle?

    <p>They bind to and activate cyclin-dependent kinases</p> Signup and view all the answers

    What is the function of oncogenes in the cell cycle?

    <p>They act as gas pedals, promoting cell division</p> Signup and view all the answers

    What leads to cancer due to mutations in the cell cycle?

    <p>Mutations in tumor suppressors</p> Signup and view all the answers

    Which checkpoint regulates the decision point on whether to replicate DNA?

    <p>G1/S checkpoint</p> Signup and view all the answers

    What regulates the Mitosis promoting factor (MPF) in the G2/M checkpoint?

    <p>Cyclin B</p> Signup and view all the answers

    What is the phase of the cell cycle that involves the separation of sister chromatids?

    <p>Mitosis</p> Signup and view all the answers

    What are oncogenes?

    <p>Mutated, dominant-acting, stimulatory genes that cause cancer</p> Signup and view all the answers

    How do tumor suppressor genes contribute to cancer?

    <p>Mutated recessive-acting inhibitory genes that are inactive</p> Signup and view all the answers

    What is the role of proto-oncogenes in normal cells?

    <p>Responsible for basic cellular functions</p> Signup and view all the answers

    How do retroviruses cause cancer?

    <p>By mutating and rearranging proto-oncogenes</p> Signup and view all the answers

    What is the main difference between forward and reverse genetics?

    <p>Forward genetics involves identifying a gene mutation based on an interesting phenotype, while reverse genetics involves mutating a gene of interest to observe resulting phenotype</p> Signup and view all the answers

    How did the Nobel Prize recipients from 2007 insert targeted mutations to alter a genome?

    <p>By using CRISPR-Cas9 technology</p> Signup and view all the answers

    What is the primary approach of reverse genetics?

    <p>Mutating a gene of interest to observe resulting phenotype</p> Signup and view all the answers

    What is CRISPR-Cas9 comprised of?

    <p>A single guide RNA and a nuclease that attach to specific DNA sequences and make double-stranded cuts</p> Signup and view all the answers

    Which repair mechanism introduces specific changes to the genome?

    <p>Homology-directed repair</p> Signup and view all the answers

    What occurs during non-homologous end joining repair?

    <p>Small, random mistakes in the fusion of DNA ends</p> Signup and view all the answers

    What is the outcome of homology-directed repair?

    <p>Introduction of specific changes to the genome</p> Signup and view all the answers

    What happens when Cas9 is mutated to only cut one strand?

    <p>It requires two different gRNAs to target one locus, reducing off-target effects</p> Signup and view all the answers

    What is the result of fusing Cas9n with reverse transcriptase?

    <p>RNA has both the targeting sequence and the sequence to be inserted</p> Signup and view all the answers

    What is the function of dead Cas9 or Cas9n fused with deaminase protein domain?

    <p>Cytosine turns into uracil, acting like thymine</p> Signup and view all the answers

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