Lecture 12 Review

A checkpoint ensuring all chromosomes are correctly attached to the spindle microtubules before sister chromatids separate during mitosis.

M-Cdk is a protein complex that drives entry into mitosis. Its activity is regulated by the degradation of M-cyclin, a key component of the complex.

A large protein complex responsible for attaching ubiquitin chains to proteins. This marks the protein for destruction by the proteasome.

A protein complex that degrades ubiquitinated proteins, effectively removing them from the cell.

A small protein that is attached to proteins as a chain ('polyubiquitylation') to mark them for destruction by the proteasome.

Enzymes that control the progression of the cell cycle by phosphorylating target proteins.

Proteins that bind to and activate Cdks. Their levels fluctuate throughout the cell cycle, triggering different phases.

A tightly controlled series of events that leads to cell growth and division.

Points in the cell cycle where progress is halted until specific conditions are met. They act as quality control mechanisms.

A checkpoint that occurs during the G2 phase of the cell cycle. It ensures that DNA replication is complete and that there is no DNA damage.,

A checkpoint at the end of the G1 phase that ensures the cell has enough nutrients and growth factors before committing to DNA replication.

The process of copying the entire DNA genome of a cell before division.

The cell cycle is divided into four phases: G1, S, G2, and M. These phases represent different stages of growth, DNA replication, and cell division.

G1 phase is the first phase of the cell cycle where the cell grows and prepares for DNA replication. During G1, the cell increases its size, synthesizes proteins, and accumulates the necessary building blocks for DNA synthesis.

S phase is the second phase of the cell cycle where DNA replication occurs. During S phase, the cell duplicates its entire genome, ensuring that each daughter cell receives a complete copy of the genetic information.

G2 phase is the third phase of the cell cycle where the cell continues to grow and prepares for mitosis. During G2, the cell synthesizes proteins necessary for mitosis, such as microtubules, organelles are duplicated, and checks for DNA damage.

M phase (mitosis) is the fourth and final phase of the cell cycle where the cell divides into two daughter cells. During mitosis, the duplicated chromosomes are segregated equally into the two daughter cells, ensuring that each daughter cell inherits a complete set of genetic information.

Cells that exit the cell cycle and no longer divide are called post-mitotic cells. They are often specialized and perform specific functions in the body. Nerve cells are a typical example.

Cells that temporarily exit the cell cycle and enter a resting phase called G0. They can re-enter the cell cycle when needed.

The mechanisms that ensure proper order and timing of events in the cell cycle are crucial to prevent errors and ensure proper cell division. These mechanisms are tightly regulated and can be disrupted in disease.

The first major checkpoint in the cell cycle, occurring right before the cell enters the S phase (DNA replication).

A protein that inhibits the activity of cyclin-dependent kinases (Cdks), particularly during the G1 phase of the cell cycle. These inhibitors help ensure that the cell only progresses into DNA replication when conditions are favorable.

A state which cells enter when they exit the cell cycle and temporarily stop dividing. They usually do this when they are no longer receiving growth signals or when environmental conditions are unfavorable.

A checkpoint that occurs during the G1 phase of the cell cycle where the cell checks for DNA damage. If damage is detected, the cell cycle is arrested, preventing the replication of damaged DNA.

A tumor suppressor gene that plays a critical role in preventing cancer. It acts as a "guardian of the genome" by stopping damaged cells from dividing and preventing them from becoming cancerous.

A protein that acts as a tumor suppressor. It is involved in the G1 checkpoint by inhibiting the function of Cdks, which prevents the cell from entering the S phase if DNA damage is present.

A protein kinase that acts as a 'brake' on the cell cycle, inhibiting CDK activity and preventing premature entry into M-phase. It ensures that the cell only proceeds to mitosis when all conditions are met.

A phosphatase that removes inhibitory phosphates from CDKs, activating them and driving the cell into M-phase. It plays a crucial role in satisfying the G2/M checkpoint and ensuring timely entry into mitosis.

A positive feedback loop in the cell cycle where active M-Cdk activates Cdc25. This results in further activation of M-Cdk, leading to a rapid and irreversible commitment to entering M-phase.

A mutation in the p53 gene leads to the loss of its tumor suppressor function. This allows damaged DNA to accumulate without repair, increasing the likelihood of mutations that can eventually lead to cancer.

The process by which normal cells accumulate mutations and progressively become cancerous. It involves multiple steps that alter the cell's behavior, leading to uncontrolled growth and division.