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 (A)</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 (B)</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 (A)</p> Signup and view all the answers

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

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

What is the movement of transposons called?

<p>Transposition (A)</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 (D)</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 (A)</p> Signup and view all the answers

How are flanking direct repeats generated during the transposition process?

<p>Cutting and leaving overlapping ends (D)</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 (D)</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 (B)</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 (C)</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 (C)</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 (A)</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 (C)</p> Signup and view all the answers

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

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

What happens to retrotransposons lacking a functional coat protein gene?

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

What kind of events are some transposition events linked to?

<p>Adaptive change (A)</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 (D)</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 (B)</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 (A)</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 (B)</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 (A)</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 (A)</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 (A)</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 (A)</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 (C)</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 (A)</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 (C)</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 (B)</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 (D)</p> Signup and view all the answers

What type of operon example does the lac operon exhibit?

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

What is the regulatory element controlling the lac operon?

<p>Inducer- allolactose (C)</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 (B)</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 (C)</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 (C)</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 (A)</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 (D)</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 (C)</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 (C)</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 (C)</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 (A)</p> Signup and view all the answers

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

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

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

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

What is the defining characteristic of euchromatin?

<p>Uniform structure (B)</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 (A)</p> Signup and view all the answers

What is the role of histone proteins in transcription?

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

Where does the process of translation occur in eukaryotic cells?

<p>In the cytoplasm (D)</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 (A)</p> Signup and view all the answers

How does histone methylation typically affect gene expression?

<p>It often causes gene silencing by repressing transcription (C)</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 (D)</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 (A)</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 (A)</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 (D)</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 (C)</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 (C)</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 (A)</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 (D)</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 (D)</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 (A)</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 (C)</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 (C)</p> Signup and view all the answers

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

<p>Inhibition of translation (A)</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 (C)</p> Signup and view all the answers

What is the defining characteristic of a benign tumor?

<p>Tumor remains localized (A)</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 (D)</p> Signup and view all the answers

What occurs during the S phase of the cell cycle?

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

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

<p>The cell prepares for mitosis (B)</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 (B)</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 (A)</p> Signup and view all the answers

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

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

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

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

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

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

What are oncogenes?

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

How do tumor suppressor genes contribute to cancer?

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

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

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

How do retroviruses cause cancer?

<p>By mutating and rearranging proto-oncogenes (B)</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 (C)</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 (C)</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 (A)</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 (C)</p> Signup and view all the answers

Which repair mechanism introduces specific changes to the genome?

<p>Homology-directed repair (A)</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 (C)</p> Signup and view all the answers

What is the outcome of homology-directed repair?

<p>Introduction of specific changes to the genome (C)</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 (B)</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 (D)</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 (C)</p> Signup and view all the answers

Flashcards

Suppressor mutation

A mutation that masks or suppresses the effects of another mutation.

Reverse mutation

A mutation that restores the wild-type gene and phenotype.

Transposable elements

DNA sequences that can move around the genome.

Intergenic mutation

A second mutation in a different gene that corrects the problem caused by the first mutation.

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Intragenic mutation

A second mutation within the same gene that corrects the problem caused by the first mutation.

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Transposition

The movement of transposable elements around the genome.

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Transposase

An enzyme that cuts out a transposon from its current location and separates it.

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Terminal inverted repeats

Sequences of 9-40 base pairs that are inverted complements of each other, found at the ends of transposable elements.

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Flanking direct repeats

Overlapping ends generated by transposase cutting the DNA during the transposition process.

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Deletion

A type of chromosomal rearrangement where two transposable elements in the same direction facilitate pairing and crossing over, resulting in a loss of DNA.

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Inversion

A type of chromosomal rearrangement where two transposable elements in opposite directions facilitate bending and crossing over, resulting in a reversal of DNA sequence.

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Deletion and duplication

A type of chromosomal rearrangement caused by misalignment and unequal exchange between transposable elements on sister chromatids, leading to gene loss or duplication.

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Composite transposons

A type of bacterial transposon characterized by genetic material flanked by two insertion sequence elements.

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DNA transposons

A specific type of eukaryotic transposable element that contains short inverted repeats and is similar to bacterial transposons.

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Tetracycline resistance

A bacterial gene insertion used as a marker for testing bacterial gene insertions, often associated with tetracycline resistance.

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Reverse transcriptase

An enzyme that creates a DNA copy from a single-stranded RNA genome, found in retrotransposons.

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Retrotransposons without coat protein

Retrotransposons lacking a functional coat protein gene are unable to leave the cell.

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Transposition and evolution

Some transposition events are linked to adaptive change, contributing to evolutionary processes.

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Mutations and evolution

Mutations are crucial for creating genetic variability, which drives evolution.

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DNA binding proteins

Proteins that regulate gene transcription by binding to DNA regulatory elements.

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Regulatory elements

DNA sequences that act as binding sites for transcription factors, which control gene expression.

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Transcription factors

Proteins that interact with other sequences to regulate transcription and translation.

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Tandem duplication

A type of chromosomal rearrangement where two parallel transposable elements cause looping and crossing over, resulting in a duplication of the segment between them.

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Regulator gene

A gene that regulates the function of an operon, but is not part of the operon itself.

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Separate regulator gene

A gene that encodes a protein that binds to the operator site and regulates the transcription of the operon.

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Operon structure

A set of genes that are co-expressed and controlled by the same regulatory elements.

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Inducible operon

An operon that requires a small molecule to turn the gene on.

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Negative repressible operon

An operon that is usually on and requires a small molecule to turn the gene off.

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Positive operon

An operon where a protein binds to DNA to activate gene expression.

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Lac operon

The lac operon is an example of a negative inducible operon, where a small molecule (allolactose) is required to turn the genes on.

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Allolactose in the lac operon

Allolactose acts as an inducer in the lac operon, binding to the regulator protein to make it inactive.

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Lac operon without lactose

In the absence of lactose, the regulator protein in the lac operon binds to the operator, blocking transcription.

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B-galactosidase

An enzyme that breaks down lactose into galactose and glucose.

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Regulator protein in the lac operon

The regulator protein in the lac operon binds to the operator in the absence of lactose, preventing transcription.

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