Study unit 4- The cell cycle

What are the four main events of cell division?

1. DNA replication - the genetic material is duplicated. 2. Chromosome segregation - the replicated genetic material is separated into two daughter cells. 3. Cytokinesis - the cytoplasm divides, forming two separate cells. 4. Cell growth - the cells grow to prepare for the next division.

What are the four main events of cell division?

The four main events of cell division are: 1) DNA replication, 2) chromosome segregation, 3) cytokinesis, and 4) cell growth.

What is binary fission in bacterial cell division?

Binary fission is the process by which bacteria divide. It involves the duplication of the ori (origin of replication) and the ter (terminus), which are essential for ensuring that the two daughter cells receive identical copies of the genetic material.

What are the phases of the eukaryotic cell cycle?

The eukaryotic cell cycle consists of three main phases: Interphase (which includes G1, S, and G2 phases) and M-phase (mitosis). In G1, the cell grows; in S-phase, DNA is replicated; and in G2, the cell prepares for mitosis.

What is the function of the G0 phase?

The G0 phase is a resting state in the cell cycle where cells exit from active division to perform specialized functions or remain metabolically active without dividing.

How do cyclins and cyclin-dependent kinases regulate the cell cycle?

Cyclins and cyclin-dependent kinases (CDKs) regulate the cell cycle by forming complexes that drive the cell through different checkpoints. For example, the G1/S cyclin-CDK complex is crucial for controlling the cell cycle at the restriction point.

What are cell cycle checkpoints?

Cell cycle checkpoints are regulatory pathways that ensure proper progression through the cell cycle. Factors that trigger checkpoints include DNA damage (G1 checkpoint), DNA replication status (S checkpoint), and proper spindle attachment (M checkpoint).

What are growth factors and their role in the cell cycle?

Growth factors are signaling molecules that stimulate cell division and proliferation. They play a key role in the cell cycle by promoting progression through checkpoints and signaling for cells to enter the division process.

Define chromatin, chromosomes, sister chromatids, and cohesin. How are they connected?

Chromatin is the complex of DNA and proteins in the nucleus; chromosomes are condensed chromatin that forms before cell division; sister chromatids are identical copies of a chromosome joined at the centromere; cohesin is the protein that holds sister chromatids together. These structures are involved in DNA organization and segregation, particularly during the S phase of the cell cycle.

What is the role of histone proteins and nucleosomes in DNA organization?

Histone proteins are essential for DNA packaging; they form nucleosomes by wrapping DNA around themselves, thereby organizing the DNA into a more compact and regulated structure.

What occurs during chromosome segregation and cytoplasmic content division in M Phase?

During M Phase, chromosomes are pulled apart to opposite poles of the cell, and the cytoplasmic contents are divided to form two separate daughter cells.

What are the phases of mitosis?

The phases of mitosis include: 1) Prophase, where chromosomes condense and the spindle apparatus forms; 2) Metaphase, where chromosomes align at the equatorial plane; 3) Anaphase, where sister chromatids are pulled apart; 4) Telophase, where chromosomes de-condense, and the nuclear envelope re-forms.

What is the anaphase-promoting complex?

The anaphase-promoting complex is a crucial regulator of the mitotic process that triggers the separation of sister chromatids by marking specific proteins for degradation. It is activated during the checkpoint to ensure accurate chromosome segregation.

How does cytokinesis differ in plant and animal cells?

Cytokinesis in animal cells is achieved through the formation of a cleavage furrow, while in plant cells, a cell plate is formed to separate the two daughter cells.

What are necrosis and apoptosis?

Necrosis is uncontrolled cell death due to injury or disease, while apoptosis is programmed cell death, characterized by a series of regulated steps leading to cell death without damaging surrounding tissue.

What is a tumor, and what are benign and malignant tumors?

A tumor is an abnormal growth of tissue. Benign tumors are non-cancerous and do not spread, while malignant tumors are cancerous and can invade nearby tissues and metastasize to other body parts.

What are oncogenes and tumor suppressor genes?

Oncogenes are mutated genes that promote cell proliferation and can lead to cancer, while tumor suppressor genes help control cell growth and prevent tumor formation. Their malfunction can contribute to cancer development.