Cell Division:

What is cell division?

The process by which cells reproduce, creating new cells from existing ones.

What is a key role of cell division in single-celled organisms?

Asexual reproduction, allowing them to create offspring.

How does cell division contribute to the growth and development of multicellular organisms?

It drives the development from a single fertilized egg (zygote).

What is tissue renewal?

The process where cell division replaces lost or damaged cells.

What is a genome?

A complete set of genetic information in a cell, encoded in DNA.

What is the difference between prokaryotic and eukaryotic genomes?

Prokaryotic genomes consist of a single DNA molecule, while eukaryotic genomes have multiple DNA molecules.

What are chromosomes?

Structures that package DNA molecules, consisting of DNA and associated proteins.

What is chromatin?

The combination of DNA and proteins that form chromosomes.

How many chromosomes do human somatic cells have?

46 chromosomes, arranged in two sets of 23.

How many chromosomes are found in human gametes?

23 chromosomes, representing one set.

What are sister chromatids?

Identical copies of a chromosome formed by DNA replication.

What is a centromere?

The region where sister chromatids are most closely attached.

What happens during cell division concerning sister chromatids?

Sister chromatids separate, becoming individual chromosomes.

What is the cell cycle?

The complete sequence of events from the formation of a new cell to its division into daughter cells.

What phases make up Interphase?

G1 phase, S phase, and G2 phase.

What occurs during the S phase of the cell cycle?

DNA replication occurs, duplicating the chromosomes.

What is mitosis?

The process where a single nucleus divides into two genetically identical daughter nuclei.

What happens during prophase in mitosis?

Chromatin fibers condense to form visible chromosomes; the nucleolus disappears.

What is the role of the mitotic spindle?

To organize and separate chromosomes during cell division.

What are motor proteins?

Proteins that carry chromosomes along microtubules during mitosis.

What is cytokinesis?

The division of the cytoplasm, resulting in two daughter cells.

What is a cleavage furrow?

A shallow groove that forms on the cell surface during cytokinesis in animal cells.

What occurs during cell plate formation in plant cells?

Vesicles coalesce to form a cell plate that grows outward to divide the cell.

What is binary fission?

A process of cell division in prokaryotes that results in two genetically identical daughter cells.

Where does DNA replication begin in binary fission?

At a specific site called the origin of replication.

What is the role of actin-like proteins in binary fission?

They contribute to chromosome movement during the process.

How is mitosis hypothesized to have evolved?

From simpler prokaryotic division mechanisms like binary fission.

What is the cell cycle control system?

A complex network of signaling molecules regulating the progression of the cell cycle.

What are checkpoints in the cell cycle control system?

Control points where stop and go-ahead signals can regulate the cycle.

What are cyclins?

Proteins whose concentration fluctuates cyclically throughout the cell cycle.

What are cyclin-dependent kinases (Cdks)?

Enzymes that are activated when binding to cyclins, driving the cell cycle.

What is density-dependent inhibition?

A phenomenon where crowded cells stop dividing.

What happens at the G1 checkpoint?

It determines whether a cell will proceed or exit into a non-dividing state (G0 phase).

What is a malignant tumor?

A tumor that can invade surrounding tissues and spread to other parts of the body.

What is metastasis?

The spread of cancer cells to distant locations from the original tumor.

What is radiation therapy?

A cancer treatment using high-energy radiation to damage DNA in cancer cells.

What is chemotherapy?

A treatment using drugs toxic to actively dividing cells.

What role does Taxol play in cancer treatment?

It prevents microtubule depolymerization, halting cell division.

What is targeted therapy?

A treatment that disrupts specific proteins or signaling pathways involved in cancer growth.

What is anchorage dependence?

The requirement for most animal cells to attach to a surface to divide.

What do cancer cells lack concerning cell cycle controls?

They lack density-dependent inhibition and anchorage dependence.

What is evasion of apoptosis in cancer cells?

The ability of cancer cells to evade programmed cell death even with significant damage.

What happens during anaphase in mitosis?

Sister chromatids are separated and moved towards opposite poles.

What is the role of GTP-bound tubulin in microtubules?

It stabilizes the plus end of microtubules and influences dynamic instability.

What are aster microtubules?

Microtubules that extend from each centrosome during mitosis.

What occurs during telophase?

Nuclear envelopes reform around separated chromosomes and nucleoli reappear.

What do cohesin proteins do?

They connect sister chromatids along their length before separation.

What are the stages of mitosis?

The stages of mitosis are prophase, prometaphase, metaphase, anaphase, and telophase.

What happens during metaphase?

Chromosomes line up at the cell's equatorial plate, and the spindle fibers attach to their centromeres.

What is the main event during anaphase?

Sister chromatids are pulled apart and move towards opposite poles of the cell.

What significant changes occur during telophase?

Nuclear envelopes reform around the separated sister chromatids, now individual chromosomes, and the nucleolus reappears.

What occurs during prophase?

The mitotic spindle begins to form and spindle fibers start to organize as chromatin condenses into visible chromosomes. Centrosomes move apart

What occurs during prometaphase?

Nuclear envelope fragments, spindle microtubules extend into nuclear envelope and attach to kinetochores on chromosomes, chromosomes are moved back and forth by attached microtubules

What is Ras?

Ras is a family of proteins involved in transmitting signals within cells, playing a crucial role in cell growth and differentiation.

How is Ras activated?

Ras is activated when it binds to guanosine triphosphate (GTP), leading to a conformational change and allowing it to interact with downstream signaling pathways.

What role does Ras play in cancer?

Mutations in Ras can lead to its continuous activation, promoting uncontrolled cell division and contributing to the development of tumors.

Oncogene

Mutated gene (Ras) that has potential to cause cancer