Podcast
Questions and Answers
What is disrupted when cells cannot load RAD51 onto ssDNA?
What is disrupted when cells cannot load RAD51 onto ssDNA?
- Branch migration
- Single-strand annealing
- Non-homologous end joining
- Homologous recombination (correct)
Cells rely solely on homologous recombination for repair when RAD51 cannot load onto ssDNA.
Cells rely solely on homologous recombination for repair when RAD51 cannot load onto ssDNA.
False (B)
What error-prone repair mechanism do cells rely on when homologous recombination is disrupted?
What error-prone repair mechanism do cells rely on when homologous recombination is disrupted?
Non-homologous end joining (NHEJ)
When RAD51 cannot load onto ssDNA, cells might employ __________ to repair DNA.
When RAD51 cannot load onto ssDNA, cells might employ __________ to repair DNA.
Match each DNA repair mechanism with its description:
Match each DNA repair mechanism with its description:
Which of the following statements is true regarding ssDNA and RAD51?
Which of the following statements is true regarding ssDNA and RAD51?
Single-strand annealing (SSA) is a reliable method for repairing DNA without errors.
Single-strand annealing (SSA) is a reliable method for repairing DNA without errors.
Name a repair mechanism that involves the joining of broken DNA ends without the need for homologous sequences.
Name a repair mechanism that involves the joining of broken DNA ends without the need for homologous sequences.
Cells experiencing disruptions in homologous recombination often rely on __________ for DNA repair.
Cells experiencing disruptions in homologous recombination often rely on __________ for DNA repair.
Match the following repair mechanisms with their characteristics:
Match the following repair mechanisms with their characteristics:
What is the core structure of a nucleosome composed of?
What is the core structure of a nucleosome composed of?
H2AX is involved in gene expression.
H2AX is involved in gene expression.
What is the function of the SWI/SNF complex?
What is the function of the SWI/SNF complex?
The ___ complex helps to disassemble and reassemble nucleosomes during transcription.
The ___ complex helps to disassemble and reassemble nucleosomes during transcription.
Match the following histone variants to their functions:
Match the following histone variants to their functions:
Which of the following enzymes is NOT involved in bacterial recombination?
Which of the following enzymes is NOT involved in bacterial recombination?
CENP-A is a variant of H3 that plays a role in centromere function.
CENP-A is a variant of H3 that plays a role in centromere function.
Name one function of the INO80 complex.
Name one function of the INO80 complex.
___ complexes are crucial for regulating chromatin structure in response to specific histone modifications.
___ complexes are crucial for regulating chromatin structure in response to specific histone modifications.
Which of the following is a function of the RuvB enzyme?
Which of the following is a function of the RuvB enzyme?
Flashcards
Nucleosome Structure
Nucleosome Structure
A nucleosome is a structural unit of DNA packaging in eukaryotes. It consists of a segment of DNA wrapped around histone proteins (H2A, H2B, H3, and H4).
Histone Variants
Histone Variants
Variations in histone proteins within the nucleosome, impacting specific functions like DNA repair, gene expression, and chromosome segregation.
SWI/SNF Complex
SWI/SNF Complex
A chromatin remodeling complex that makes DNA accessible for transcription by sliding, ejecting, and altering nucleosome structure.
Chromatin Remodeling Complexes
Chromatin Remodeling Complexes
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INO80 complex function
INO80 complex function
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ISWI complexes
ISWI complexes
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CHD complexes
CHD complexes
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FACT complex
FACT complex
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RecA
RecA
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RAD51
RAD51
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Error-prone repair mechanisms
Error-prone repair mechanisms
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Non-homologous end joining (NHEJ)
Non-homologous end joining (NHEJ)
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Single-strand annealing (SSA)
Single-strand annealing (SSA)
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Branch migration
Branch migration
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ssDNA
ssDNA
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Homologous recombination
Homologous recombination
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Disrupts HR
Disrupts HR
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Cells rely on error-prone repair mechanisms
Cells rely on error-prone repair mechanisms
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Damaged DNA
Damaged DNA
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Study Notes
Chromatin and Epigenetics
- Nucleosomes are composed of H2A, H2B, H3, and H4 proteins
- H3 and H4 dimers combine to form tetramers
- Tetramers bind two H2A-H2B dimers forming an octamer
- 147 base pairs (bp) of DNA are wrapped around an octamer
- DNA linker regions are 38-53 bp long
- Histone variants, such as H2A.Z and H2AX, have specific functions
- H2AX is involved in DNA repair
- H2A.Z aids in gene expression
- Histone variants like macroH2A are involved in transcriptional repression
Remodeling Complexes
- SWI/SNF complex alters nucleosome structure
- Crucial for DNA accessibility for transcription
- Slides and ejects nucleosomes
- Second most mutated gene family across various cancers
- INO80 complex is another remodeling complex, involved in nucleosome sliding
- Crucial in histone exchange/replacement, particularly H2A.Z, essential for transcription
- Important in DNA damage repair, makes damaged DNA accessible to repair machinery
- Plays a key role in replication stress response by stabilizing replication forks and preventing stress
- Any condition that slows or disrupts replication is countered by stress response
Genetic Recombination
- Enzymes play vital roles in bacterial/eukaryotic recombination
- Enzymes like RecA, RecB, RecC, RecD, RuvC, RuvA, RuvB, RecG, RAD50, XRS2, MRE11, Sae2, Tel1, RAD51, RAD52, and BRAC2 play crucial roles in the process
- Some functions across different systems (bacterial or eukaryotic)
- Holliday junctions are key structures during recombination.
- Branch migration is a critical step during recombination. Mechanisms in eukaryotes include:
- Non-homologous end joining (NHEJ)
- Single-strand annealing (SSA)
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