Chromosome Anatomy
Eukaryotic chromosomes are composed of this complex, which is approximately 40% DNA and 60% protein.
The specific phase within Interphase where DNA synthesis and chromosome replication occur.
During this stage, all chromosomes align along an imaginary equator called the metaphase plate.
This class of enzymes regulates the cycle by phosphorylating target proteins after being activated by binding to specific regulatory proteins.
Cancer is fundamentally described as the failure of cell cycle control, leading to this.
This fundamental unit of chromatin consists of a negatively charged DNA molecule wrapped around a core of eight positively charged histone proteins.
This phase is the primary growth phase of the cell and is typically the longest part of the cell cycle.
This stage begins when centromeres split and sister chromatids are pulled toward opposite poles of the cell.
This checkpoint assesses the success of DNA replication and ensures DNA integrity before the cell makes a commitment to mitosis.
These normal cellular genes lead to uncontrolled cell division if only one copy undergoes a "gain-of-function" mutation.
In humans, somatic cells contain 46 chromosomes in 23 nearly identical pairs, a condition known as this.
These three distinct phases (G1, S, and G2) collectively account for the majority of a cell's life cycle.
The first stage of mitosis, during which chromosomes first become visible with a light microscope and the nuclear envelope breaks down.
Often called the "start" or restriction point, this is the primary point where external signals influence the cell's decision to divide.
Both copies of this type of gene must lose function for a cancerous phenotype to develop, as they normally act as "brakes" on the cell cycle.
This specific domain of chromatin is loosely packed and actively involved in gene expression.
Mature cells that are not actively dividing, such as some human liver cells, enter this "resting" phase.
In animal cells, cytokinesis involves the constriction of actin filaments to form this, while plant cells form a cell plate.
This checkpoint ensures that all chromosomes are properly attached to the spindle apparatus before the irreversible separation of sister chromatids begins.
Known as the "guardian of the genome," this protein monitors DNA integrity at the G1 checkpoint and is damaged or absent in 50% of all cancers.
These two identical DNA molecules are held together by cohesin proteins following DNA replication.
During this sub-phase of Interphase, organelles replicate, microtubules begin to organize, and chromosomes coil more tightly using motor proteins.
This stage is characterized by the spindle apparatus disassembling and nuclear envelopes reforming around two new sets of chromosomes.
This complex, discovered in frog oocytes, is necessary for triggering the M phase and its activity is controlled by the phosphorylation of Cdc2.
Mutations in this specific tumor-suppressor gene, which integrates signals from growth factors, were the first identified in a rare form of retina cancer.