Genomic Instability and DNA Replication

A state where cells have an increased tendency to acquire inheritable genetic changes, influencing their characteristics.

A type of genomic instability involving changes in the number of repeats in short, repetitive DNA sequences called microsatellites.

A type of genomic instability characterized by changes in the structure or number of chromosomes.

A type of chromosomal instability involving changes in the structure of chromosomes, such as deletions, duplications, inversions, or translocations.

A type of chromosomal instability involving changes in the number of chromosomes. This can include aneuploidy (missing or extra chromosomes) or polyploidy (having extra sets of chromosomes).

A type of genomic instability where there are changes in the DNA sequence at the nucleotide level, including substitutions, insertions, or deletions.

A type of genotoxic agent that damages DNA by interacting with it directly.

A type of genotoxic agent that causes damage to DNA by absorbing UV radiation and forming dimers between adjacent thymine bases, disrupting the structure and function of DNA.

An external factor that causes damage to DNA, specifically by altering the chemical structure of DNA bases leading to mutations.

A form of radiation that can directly interact with DNA, causing breaks in the DNA backbone or altering bases, leading to mutations.

A type of damage to DNA where the bases are modified or removed, leading to errors in replication, leading to mutations.

A DNA repair pathway that focuses on recognizing and fixing errors in DNA replication, ensuring accuracy in copying the genetic information.

A set of proteins and pathways that detects DNA damage, initiates repair mechanisms, and decides whether to repair the damage or trigger cell death, thus maintaining genome integrity.

A process involving multiple pathways that recognize and repair damaged DNA. This includes base excision repair, nucleotide excision repair, and double-strand break repair.

The process of copying the genetic information from DNA to RNA, which then directs protein synthesis.

The process of synthesizing proteins based on the instructions carried by mRNA, ultimately creating the functional units of cells.

The process by which DNA damage is detected and signals are sent to initiate repair.

A mechanism used by cells to repair damaged DNA by removing and replacing a segment of the damaged strand.

A major DNA repair pathway that uses a homologous chromosome as a template to accurately repair double-strand breaks.

A process that joins broken DNA ends together, but may introduce mutations.

The process of repairing damaged bases in DNA by removing and replacing them.

A DNA repair protein that plays a critical role in repairing double-strand breaks and activating cell cycle checkpoints.

The process of replicating DNA, which involves multiple steps, including initiation, licensing, and activation.

Centromeric non-coding RNAs are specialized RNA molecules located at the centromere, a constricted region of a chromosome critical for proper chromosome segregation during cell division. They contribute to the formation and maintenance of the centromere structure, ensuring accurate chromosome inheritance.

Telomeres are protective caps at the ends of chromosomes, preventing degradation and fusion of DNA strands. They consist of repetitive DNA sequences and associated proteins.

Telomerase is an enzyme crucial for maintaining telomere length. It adds repetitive DNA sequences to the ends of chromosomes, compensating for the shortening that occurs during cell division.

Transposable elements (TEs) are DNA segments that can move around within a genome, sometimes causing mutations or rearrangements. They are categorized into two main classes: Class 1 (retrotransposons) and Class 2 (DNA transposons). They play a significant role in genome evolution but can also contribute to genomic instability.

Histone modifications and DNA methylation are crucial epigenetic mechanisms that involve modifications to the DNA or surrounding proteins, altering gene expression without changing the underlying DNA sequence. They play a significant role in regulating transposable element activity, preventing uncontrolled transposition and maintaining genomic stability.

The mitotic checkpoint is a crucial control mechanism that ensures the proper segregation of chromosomes during cell division. This checkpoint monitors the alignment of chromosomes at the metaphase plate, preventing the separation of chromosomes until all are correctly attached to spindle fibers. It is active during prometaphase, metaphase, and anaphase, preventing premature separation and ensuring genome stability.

DNA methylation is a crucial epigenetic mechanism that involves the addition of a methyl group to cytosine bases in DNA. This modification influences chromatin structure, gene expression, and genomic stability. In the context of genome stability, DNA methylation plays a vital role in silencing transposable elements (TEs), protecting against insertional mutagenesis.

Hypomethylation refers to a decrease in DNA methylation levels. It can lead to genomic instability by reactivating TEs, which can disrupt gene function and cause mutations. Hypermethylation is an increase in DNA methylation levels. It can contribute to genomic instability by suppressing tumor suppressor genes, promoting cancer development, and influencing telomere integrity.

Nucleosome remodeling is a dynamic process that involves changes in the positioning and accessibility of nucleosomes along the DNA. This process is essential for regulating gene expression, DNA replication, and DNA repair. It involves several steps, including nucleosome assembly, where a DNA segment wraps around histone proteins to form a nucleosome, and chromatin access, where regions of DNA are made accessible for transcription factors and other proteins.

Histone modifications refer to various chemical changes made to histone proteins, such as methylation, acetylation, and phosphorylation. These modifications alter the accessibility of DNA to transcription factors, influencing gene expression and chromatin structure. They can lead to either open chromatin, a more relaxed state that allows for gene expression, or closed chromatin, a tightly packed state that restricts gene expression.

Epigenetic mechanisms refer to heritable changes in gene expression that don't involve alterations to the DNA sequence. They play a crucial role in regulating genome stability by influencing chromatin structure, gene expression, and DNA repair. These mechanisms include DNA methylation, histone modifications, and noncoding RNA regulations.

Disruptions in epigenetic mechanisms, such as alterations in histone modifications, DNA methylation, and noncoding RNA levels, can lead to genomic instability. These disruptions can cause errors in DNA replication, repair, and gene expression, increasing the risk of mutations and diseases like cancer. For example, aberrant histone modifications can weaken DNA repair mechanisms, leading to increased mutation rates.

Epigenetics plays a crucial role in regulating genomic stability through various mechanisms. Histone modifications control chromatin accessibility, influencing gene expression and DNA repair. DNA modifications, such as methylation, affect TE regulation, gene silencing, and replication fidelity. TE regulation prevents insertional mutagenesis. Noncoding RNA regulates gene expression and chromatin structure, contributing to proper genome maintenance.

A protein involved in DNA repair that is phosphorylated in response to DNA damage. This phosphorylation serves as a signal for the recruitment of other DNA repair proteins to the site of damage.

A type of histone modification that promotes the recruitment of repair proteins to the site of DNA damage. This methylation pattern helps to ensure that the correct repair pathway is chosen based on the type of damage.

A complex of proteins that can alter the structure of chromatin, making it more accessible to DNA repair proteins. These complexes are crucial in regulating the choice between different DNA repair pathways.

The process by which DNA is replicated. During this process, the DNA molecule is unwound and copied, producing two identical copies. This replication process can be disrupted by various factors, including DNA damage.

These are points on chromosomes where sister chromatids attach during cell division. They play a crucial role in chromosome segregation, ensuring that each daughter cell receives a complete set of chromosomes.

A protein that is only found in centromeres and helps to establish the kinetochore, the structure that connects chromosomes to microtubules during cell division. This localization is specific to this region of the chromosome.

Errors in the replication process can lead to stalled replication forks, where the replication machinery is halted and DNA synthesis is blocked. These stalled forks are potential sources of DNA damage and genomic instability.

A type of post-translational modification on histones that influences the recruitment of repair proteins to the site of damage. This modification acts as a signal for the repair machinery to respond to DNA damage effectively.