Cell Cycle and Cytokinesis

These flashcards focus on the cell cycle, cytokinesis in both plant and animal cells, and the regulation and abnormalities in cell division related to cancer.

What is cytokinesis in animal cells characterized by?

Cytokinesis in animal cells occurs by cleavage, leading to the formation of a cleavage furrow.

What signals the beginning of cytokinesis in animal cells?

The appearance of a cleavage furrow is the first sign of cytokinesis in animal cells.

What is a cleavage furrow?

A cleavage furrow is a shallow groove in the cell surface near the old metaphase plate.

What is produced at the end of cytokinesis in animal cells?

Two completely separated daughter cells, each with its own nucleus and organelles.

What occurs during cytokinesis in plant cells?

In plant cells, cytokinesis involves the formation of a cell plate instead of a cleavage furrow.

What is a cell plate?

A cell plate is a membrane-bound flattened sac that forms at the midline of a dividing plant cell.

During which phase do vesicles move to the middle of a plant cell to form a cell plate?

During telophase.

What happens to the cell plate during cytokinesis in plant cells?

The cell plate enlarges and fuses with the plasma membrane.

What is binary fission?

Binary fission is a method of asexual reproduction where a prokaryotic cell grows and divides to form two cells.

In which cells does binary fission occur?

Binary fission occurs in prokaryotic cells.

During which stage do chromosomes consist of two identical chromatids?

During interphase, specifically in the G2 phase.

What is the primary regulation system of the eukaryotic cell cycle?

The eukaryotic cell cycle is regulated by a molecular control system.

Name a type of cell that rarely divides.

Mature nerve or cardiac cells do not divide.

Where does evidence for the cell cycle control system come from?

Experiments involving fusing cells in different phases of the cell cycle.

What are cyclins and cyclin-dependent kinases?

Cyclins are proteins that fluctuate in concentration, regulating cell cycle control with cyclin-dependent kinases.

What role does MPF play in the cell cycle?

MPF triggers the cell's progression from late interphase to mitosis.

What happens at the G1 checkpoint in the cell cycle?

Cells either receive a go-ahead signal to divide or exit into a non-dividing state called G0.

What is the significance of the M checkpoint?

It ensures that all chromosomes are properly attached to the spindle before anaphase begins.

What is density-dependent inhibition?

It is the phenomenon where crowded cells stop dividing.

What is anchorage dependence?

It refers to the requirement that a cell must be attached to some surface to divide.

How do cancer cells differ from normal cells in terms of cell division controls?

Cancer cells do not exhibit density-dependent inhibition or anchorage dependence.

What can lead to the transformation of a normal cell into a cancer cell?

Mutations that alter the function of proteins controlling the cell cycle.

What do cancer cells often evade?

Cancer cells evade apoptosis and continue dividing despite abnormalities.

What distinguishes a benign tumor from a malignant tumor?

A benign tumor remains at the original site, while a malignant tumor can spread to new tissues.

What is a common characteristic of most cells in the human body?

Most cells are in the G0 phase and do not actively divide.

What molecules are involved in regulating the cell cycle?

Cyclins and cyclin-dependent kinases (Cdks).

What happens to a cell that does not receive a go-ahead signal at the G1 checkpoint?

It may exit the cell cycle and enter the G0 phase.

What influences the timing and rate of cell division?

A molecular control system that regulates the cell cycle at specific checkpoints.

How does the fluctuation of cyclins affect cell cycle progression?

The activity of cyclin-dependent kinases rises and falls with cyclin concentration.

What must happen for a Cdk to be active?

It must be attached to a cyclin.

Why is the G2 checkpoint important?

It ensures the cell is ready to enter mitosis after DNA is replicated.

What checkpoints are found in the eukaryotic cell cycle?

The G1, G2, and M checkpoints.

How do cancer cells grow in culture?

Cancer cells can divide indefinitely if given a continual supply of nutrients.

What is the effect of cell-to-cell contact on cell division?

It inhibits further cell division through density-dependent inhibition.

What is the role of growth factors in cell division?

Growth factors stimulate other cells to divide.

What is the result of the S phase checkpoint?

It stops cells with DNA damage from proceeding in the cell cycle.

What happens at the checkpoint between anaphase and telophase?

It ensures anaphase is complete before cytokinesis begins.

What can cause cancer cells to ignore normal division signals?

Mutations that alter their protein products or signaling pathways.

How do cancer cells respond to growth factor depletion?

They do not stop dividing when growth factors are depleted.

How are the functions of anchorage dependence described?

Cells must be attached to a substrate or extracellular matrix to initiate division.

What can alter normal cell cycle control in cancer?

Accumulation of mutations and abnormal signaling pathways.

What characterizes the behavior of cancer cells at checkpoints?

They stop dividing randomly rather than at normal checkpoints.