Cell Cycle and Mitosis: Key Concepts for Biology Students

What is the role of cell division in unicellular organisms?

It reproduces the entire organism.

List three reasons why multicellular eukaryotes depend on cell division.

Development from a fertilized egg, growth, and repair.

What is the cell cycle?

The life of a cell from formation to its own division.

What is the typical outcome of cell division?

Two daughter cells with identical genetic information.

What is meiosis?

A special type of cell division that produces sperm and egg cells.

What constitutes a cell's genome?

All the DNA in a cell.

How is DNA organized in eukaryotic cells?

DNA molecules are packaged into chromosomes.

What is chromatin?

A complex of DNA and protein that condenses during cell division.

How many sets of chromosomes do somatic cells have?

Two sets (pairs of chromosomes).

How many chromosomes do gametes have compared to somatic cells?

Half as many chromosomes.

What happens to DNA in preparation for cell division?

DNA is replicated and chromosomes condense.

What are sister chromatids?

Joined copies of the original chromosome.

What is the centromere?

The narrow 'waist' of the duplicated chromosome where sister chromatids are attached.

What are the two main processes of eukaryotic cell division?

Mitosis and cytokinesis.

What is the mitotic phase?

The phase of the cell cycle that includes mitosis and cytokinesis.

What are the three phases of interphase?

G1 phase, S phase, and G2 phase.

During which phase are chromosomes duplicated?

S phase.

What are the five stages of mitosis?

Prophase, prometaphase, metaphase, anaphase, and telophase.

What is the mitotic spindle?

A structure made of microtubules that controls chromosome movement during mitosis.

What is the role of the centrosome during cell division?

It organizes microtubules and replicates to form two centrosomes that migrate to opposite ends of the cell.

What occurs during anaphase?

Sister chromatids separate and move toward opposite ends of the cell.

What is cytokinesis?

The division of the cytoplasm to form two daughter cells.

How does cytokinesis differ in animal and plant cells?

In animal cells, it occurs by cleavage forming a cleavage furrow; in plant cells, a cell plate forms.

What is the 'Pac-man' mechanism?

The process by which motor proteins on kinetochores 'walk' chromosomes along shortening microtubules during anaphase.

What happens to nonkinetochore microtubules during anaphase?

They overlap and push against each other, elongating the cell.

What is the significance of the metaphase plate?

It is the plane where chromosomes are lined up midway between the spindle's two poles during metaphase.

What is the function of kinetochores?

They are protein complexes associated with centromeres that attach to spindle microtubules.

What is the outcome of mitosis?

Two genetically identical daughter cells.

What type of cell division do prokaryotes use?

Binary fission

What happens during binary fission?

The chromosome replicates, and the two daughter chromosomes move apart as the plasma membrane pinches inward.

What is the significance of the origin of replication in binary fission?

It is the starting point where chromosome replication begins.

How does binary fission result in new cells?

It divides the cell into two daughter cells after replication and separation of chromosomes.

How is mitosis related to binary fission?

Mitosis probably evolved from binary fission, as prokaryotes evolved before eukaryotes.

What regulates the frequency of cell division in eukaryotes?

Regulation occurs at the molecular level, influenced by specific chemical signals.

What role do cyclins and cyclin-dependent kinases (Cdks) play in the cell cycle?

They are regulatory proteins involved in controlling the progression of the cell cycle.

What is MPF and its function?

Maturation-promoting factor (MPF) is a cyclin-Cdk complex that triggers a cell's passage past the G2 checkpoint into the M phase.

What happens at the G1 checkpoint?

The cell checks if division is necessary, if it is large enough, and if sufficient nutrients are available.

What is the G0 phase?

A nondividing state that a cell enters if it does not receive a go-ahead signal at the G1 checkpoint.

What does the G2 checkpoint assess?

It checks if DNA was replicated correctly and if the cell is large enough.

What does the M checkpoint ensure?

It ensures that all chromosomes are attached to microtubules before proceeding with cell division.

What is density-dependent inhibition?

A phenomenon where crowded cells stop dividing.

What is anchorage dependence?

The requirement for cells to be attached to a substratum in order to divide.

How do cancer cells differ from normal cells in terms of growth factors?

Cancer cells do not need growth factors to grow and divide; they may produce their own or respond abnormally to signals.

What is a benign tumor?

A lump of abnormal cells that remains at the original site without invading surrounding tissues.

What is metastasis?

The spread of cancer cells to other parts of the body, forming additional tumors.

What treatments are used for localized tumors?

High-energy radiation is used to damage the DNA in cancer cells.

What recent advancements have been made in cancer treatment?

Advances in understanding the cell cycle and signaling have led to more personalized cancer treatments.

What is the role of external signals at cell cycle checkpoints?

External signals can influence cell division and are often related to growth factors.

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

The cell exits the cycle and enters the G0 phase.

What is the importance of checkpoints in the cell cycle?

They ensure that the cell is ready to proceed to the next phase of division.

What occurs during the S phase of the cell cycle?

DNA is synthesized and chromosomes are replicated.

What happens during the M phase of the cell cycle?

Mitosis occurs, leading to the division of the cell's nucleus.

What is the significance of the cell cycle control system?

It directs the sequential events of the cell cycle and ensures proper timing and regulation.

How do cancer cells exhibit loss of cell cycle controls?

They do not respond to normal regulatory mechanisms and can divide indefinitely.