Podcast
Questions and Answers
What type of mutation results in the protein being truncated?
What type of mutation results in the protein being truncated?
- Silent mutation
- Missense mutation
- Frameshift mutation
- Nonsense mutation (correct)
Which type of mutation occurs when a purine is replaced by a pyrimidine?
Which type of mutation occurs when a purine is replaced by a pyrimidine?
- Transversion mutation (correct)
- Point mutation
- Insertion mutation
- Transition mutation
What can somatic cell mutations potentially cause?
What can somatic cell mutations potentially cause?
- Diseases such as cancer (correct)
- Heritable defects
- Developmental defects
- Protein expression changes
Which category of mutations can affect transcriptional regulation?
Which category of mutations can affect transcriptional regulation?
How does a missense mutation affect protein structure?
How does a missense mutation affect protein structure?
What is the role of DNA-damaging agents in cancer therapy?
What is the role of DNA-damaging agents in cancer therapy?
What is the main consequence of a silent mutation?
What is the main consequence of a silent mutation?
Which type of mutation affects adult size and shape in progeny?
Which type of mutation affects adult size and shape in progeny?
What is codon bias?
What is codon bias?
What is the primary method by which 99% of spontaneous replication errors are corrected?
What is the primary method by which 99% of spontaneous replication errors are corrected?
Spontaneous mutations can arise during which of the following processes?
Spontaneous mutations can arise during which of the following processes?
Why is mismatch repair important?
Why is mismatch repair important?
How often does DNA polymerase typically make replication errors?
How often does DNA polymerase typically make replication errors?
What is a potential side effect of chemotherapy or radiotherapy?
What is a potential side effect of chemotherapy or radiotherapy?
Which of the following is NOT a characteristic of cancer cells?
Which of the following is NOT a characteristic of cancer cells?
What role does proofreading activity play in DNA replication?
What role does proofreading activity play in DNA replication?
What can cause DNA damage leading to mismatches during DNA synthesis?
What can cause DNA damage leading to mismatches during DNA synthesis?
What can DNA slippage lead to?
What can DNA slippage lead to?
Which term describes a mutation caused by external factors?
Which term describes a mutation caused by external factors?
What method is commonly used to repair mismatches in DNA?
What method is commonly used to repair mismatches in DNA?
What typically accounts for most replication errors?
What typically accounts for most replication errors?
Which of the following statements is false regarding silent mutations?
Which of the following statements is false regarding silent mutations?
What can cause a wrong base to be inserted during DNA replication?
What can cause a wrong base to be inserted during DNA replication?
What sequence is used by CRISPR to identify the target DNA for cutting?
What sequence is used by CRISPR to identify the target DNA for cutting?
Which components are essential for Cas9 to successfully cut DNA?
Which components are essential for Cas9 to successfully cut DNA?
What is the role of the guide RNA in the CRISPR/Cas9 system?
What is the role of the guide RNA in the CRISPR/Cas9 system?
What is a significant characteristic of the CRISPR system in bacteria?
What is a significant characteristic of the CRISPR system in bacteria?
In genome editing using CRISPR/Cas9, what is a potential outcome for the target organism?
In genome editing using CRISPR/Cas9, what is a potential outcome for the target organism?
What is one way that CRISPR can be introduced into the target organism?
What is one way that CRISPR can be introduced into the target organism?
What is the role of trancrRNA in the CRISPR/Cas9 system?
What is the role of trancrRNA in the CRISPR/Cas9 system?
What type of organisms have been cited as editable using the CRISPR/Cas9 technique?
What type of organisms have been cited as editable using the CRISPR/Cas9 technique?
What is the primary role of MutS in the mismatch repair process?
What is the primary role of MutS in the mismatch repair process?
Which statement accurately describes the actions of MutH in mismatch repair?
Which statement accurately describes the actions of MutH in mismatch repair?
Which gene defects are commonly associated with hereditary non-polyposis colon cancer?
Which gene defects are commonly associated with hereditary non-polyposis colon cancer?
In which organism's DNA repair system are MSH and MLH genes first studied?
In which organism's DNA repair system are MSH and MLH genes first studied?
What is the first step in base excision repair?
What is the first step in base excision repair?
What type of mutations are associated with hereditary non-polyposis colon cancer?
What type of mutations are associated with hereditary non-polyposis colon cancer?
What enzyme is known to be missing in eukaryotes for incision during mismatch repair?
What enzyme is known to be missing in eukaryotes for incision during mismatch repair?
Which repair pathway involves excision of a damaged region and using complementary DNA as a template?
Which repair pathway involves excision of a damaged region and using complementary DNA as a template?
What type of DNA damage is primarily repaired by nucleotide excision repair?
What type of DNA damage is primarily repaired by nucleotide excision repair?
Which proteins are part of the multienzyme complex in bacteria involved in nucleotide excision repair?
Which proteins are part of the multienzyme complex in bacteria involved in nucleotide excision repair?
What is a major consequence of uncorrected DNA double-strand breaks?
What is a major consequence of uncorrected DNA double-strand breaks?
What is the role of DNA helicase in nucleotide excision repair?
What is the role of DNA helicase in nucleotide excision repair?
Xeroderma pigmentosum is associated with a defect in which DNA repair mechanism?
Xeroderma pigmentosum is associated with a defect in which DNA repair mechanism?
What is a primary method of repair for DNA double-strand breaks?
What is a primary method of repair for DNA double-strand breaks?
What is the initial step in the homologous recombination repair process?
What is the initial step in the homologous recombination repair process?
What is a critical function of ligase in DNA repair mechanisms?
What is a critical function of ligase in DNA repair mechanisms?
Flashcards
Point Mutation
Point Mutation
A type of mutation that changes a single base pair in a DNA sequence.
Insertion Mutation
Insertion Mutation
A mutation where one or more base pairs are added to the DNA sequence.
Deletion Mutation
Deletion Mutation
A mutation where one or more base pairs are removed from the DNA sequence.
Germ Cell Mutation
Germ Cell Mutation
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Somatic Cell Mutation
Somatic Cell Mutation
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Homologous recombination
Homologous recombination
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CRISPR/Cas9 system
CRISPR/Cas9 system
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CRISPR
CRISPR
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Cas9
Cas9
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Guide RNA (gRNA)
Guide RNA (gRNA)
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Double-stranded break
Double-stranded break
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Genome editing
Genome editing
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Knock-out mutant
Knock-out mutant
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Silent mutation
Silent mutation
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Codon bias
Codon bias
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Spontaneous mutations
Spontaneous mutations
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DNA replication errors
DNA replication errors
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Proofreading activity
Proofreading activity
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5' slippage
5' slippage
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CAG expansion
CAG expansion
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What are spontaneous base modifications?
What are spontaneous base modifications?
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Progeny
Progeny
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Mutant
Mutant
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DNA Repair Mechanisms
DNA Repair Mechanisms
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Mismatch Repair
Mismatch Repair
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Excision Repair
Excision Repair
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Alkylating Agents
Alkylating Agents
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Side Effects of Chemotherapy
Side Effects of Chemotherapy
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Methylation
Methylation
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Lynch Syndrome
Lynch Syndrome
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Base Excision Repair
Base Excision Repair
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Nucleotide Excision Repair
Nucleotide Excision Repair
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Xeroderma pigmentosum (XP)
Xeroderma pigmentosum (XP)
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DNA Double-Strand Break
DNA Double-Strand Break
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Homologous Recombination (HR)
Homologous Recombination (HR)
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Non-homologous End-Joining (NHEJ)
Non-homologous End-Joining (NHEJ)
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Exonuclease (in DNA repair)
Exonuclease (in DNA repair)
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DNA Polymerase (in DNA repair)
DNA Polymerase (in DNA repair)
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Ligase (in DNA repair)
Ligase (in DNA repair)
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Study Notes
DNA Mutation and Repair
- Learning Outcomes:
- Explain DNA structure, organization, DNA replication mechanisms, and repair mechanisms.
- Demonstrate understanding of various modern molecular biology techniques.
- Peppered Moth Example:
- A study identified the gene responsible for the peppered moth adapting to pollution by turning black.
- This adaptation occurred due to a genetic mutation.
- Types of Mutations:
- Mutations alter DNA sequence.
- Point mutation: A single nucleotide change.
- Insertion: Addition of one or more nucleotides.
- Deletion: Removal of one or more nucleotides.
- Transversion mutation: A purine is replaced by a pyrimidine, or vice-versa.
- Transition mutation: A purine is replaced by a purine, or a pyrimidine is replaced by a pyrimidine.
- Location of Mutations:
- Germ cells (sperm/eggs): Cause heritable defects.
- Somatic cells (non-reproductive cells): Can cause diseases like cancer.
- Cells in developing embryos: Can lead to developmental defects.
- Effects of Mutations in Genes:
- Coding genes: Affect protein expression or structure.
- Non-coding RNA (e.g., rRNA, tRNA): Affect translation, transcription, or splicing.
- Non-transcribed regions (e.g., promoters, enhancers): Affect transcriptional regulation.
- Mutations can occur anywhere in the genome.
- Effects on Proteins:
- Nonsense mutation: Truncates the protein.
- Missense mutation: Changes a single amino acid.
- Frameshift mutation: Changes the reading frame, altering subsequent amino acids.
- Silent mutation: No effect on the amino acid sequence.
- Silent Mutations:
- No effect on amino acid sequences.
- Can affect transcription or translation.
- Multiple codons may code for a single amino acid.
- Some organisms prefer particular codons for an amino acid (codon bias).
- DNA Mutations:
- Spontaneous (occur during normal cellular processes):
- Errors during DNA replication.
- Modifications of DNA bases.
- Replication errors (wrong bases, skipping bases).
- Spontaneous (occur during normal cellular processes):
- Replication Errors:
- Most replication errors are corrected by proofreading activity of DNA polymerase (3' to 5' exonuclease activity).
- Errors are relatively rare (1 in 105 to 106 base pairs).
- Replication slippage:
- Can potentially result in repetitive sequences, as errors accumulate (e.g., in the Huntingtin gene, associated with Huntington's disease).
- Induced Mutations:
- Caused by exogenous agents (mutagens).
- Discuss examples of mutagens in pairs.
- Caused by exogenous agents (mutagens).
- Use of Mutations in Research:
- Mutagens (e.g., EMS, ENU) can be used to create targeted mutations.
- This allows mutations in genes to be linked to phenotypes and help identify genes involved in diseases.
- Use of Mutations in Therapy:
- DNA-damaging agents (e.g., chemo/radiotherapy) are more effective against rapidly dividing cancer cells.
- DNA repair:
- Many repair systems exist to maintain genetic stability following DNA damage.
- Repair of Mismatches:
- Mismatches arise during DNA synthesis & other ways
- ~99% of replication errors repaired by DNA polymerase's proofreading (3' to 5' exonuclease activity)
- Mismatch repair (in E. coli);
- MutS recognizes mismatch.
- MutL activates MutH.
- MutH creates a nick nearby the methylated sequence.
- Mismatch Repair in Humans:
- Similar process in humans.
- Uses MutS homologs (MSH1, MSH2) and MutL homologs (MLH1).
- Mismatch Repair and Colon Cancer:
- A defect of Mismatch repair enzymes is involved in hereditary non-polyposis colon cancer (HNPCC, aka Lynch syndrome).
- Excision Repair:
- Base excision repair: Removes damaged bases.
- Nucleotide excision repair: Removes damaged segments of DNA.
- Double-Strand Breaks:
- Difficult to repair.
- Homologous Recombination:
- Involves pairing with a homologous DNA sequence.
- More complex than other repair mechanisms.
- Non-homologous End Joining (NHEJ):
- Repairs double-strand DNA breaks.
- CRISPR/Cas9 system
- Bacterial defense system creating 'immunological memory'
- Bacteria cuts foreign DNA.
- Uses Guide RNA to target a specific DNA sequence and cuts the targeted DNA
- Used in genome editing.
- Genome Editing Using CRISPR/Cas9:
- Used to introduce targeted mutations.
- What Next?
- Further research to explore the potential in therapeutic applications and ethical considerations.
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Description
Explore the mechanisms of DNA structure, replication, and repair in this quiz. Understand various types of mutations with real-world examples like the peppered moth. Test your knowledge on the implications of mutations in germ and somatic cells.
