UNIT 5.1 CELL CYCLE & CELL DIVISION

What are the three main stages of the cell cycle?

Interphase, Mitosis, and Cytokinesis.

What happens during Interphase?

It is a pattern of growth, DNA replication, and cell division preparation. It includes G1, S, and G2 phases.

What occurs during the G1 (Gap 1) phase of the cell cycle?

Cells grow, carry out normal functions, and replicate their organelles. Most of the cell's time is spent here.

What is the primary event during the S (Synthesis) phase?

DNA replication occurs

What happens in the G2 (Gap 2) phase?

Additional growth occurs to prepare for cell division.

What is Mitosis (M) responsible for?

The division of the nucleus and subsequently the cytoplasm (cytokinesis).

Which types of cells often enter the G0 (G Zero) stage, where they cease dividing?

Neurons and some immune cells.

Why is the ratio of surface area to volume important for cell size?

Surface area must be large enough to allow for the effective exchange of materials.

What are external factors that regulate cell division?

Physical and chemical signals, such as growth factors.

What are growth factors?

EXTERNAL REGULATORY PROTEINS

What are internal factors that regulate cell division?

Kinases and cyclins.

What is apoptosis?

Programmed cell death

What is cancer?

Uncontrolled cell growth.

What is a tumor?

A mass of disorganized cells resulting from uncontrolled cell growth.

What are carcinogens?

Cancer-causing substances.

Define metastasis.

The process by which cancer spreads to other parts of the body.

What is the difference between a benign and malignant tumor?

A benign tumor is not spreading, while a malignant tumor can spread.

What are oncogenes?

Genes that can cause cancer.

How is a chromosome structured?

Each double-stranded DNA molecule makes one chromosome, DNA wraps around histones forming chromatin, which then coils tightly.

What are two identical chromosomes connected by?

A centromere, forming two sister chromatids.

What are telomeres and what are they related to?

Protective caps at the ends of chromosomes, related to aging.

What is the main event of Prophase in mitosis?

Genetic material condenses, and the nuclear membrane breaks down, making chromosomes visible.

What characterizes Metaphase during mitosis?

Chromosomes line up along the middle (equator) of the cell.

What occurs during Anaphase in mitosis?

Sister chromatids separate and move to opposite sides of the cell.

What happens in Telophase of mitosis?

Nuclear membranes return, chromosomes begin to uncoil, and spindle fibers disappear.

How does cytokinesis differ in animal cells versus plant cells?

Animal cells 'pinch' inward to divide, while plant cells form a cell plate.

What is asexual reproduction?

Reproduction involving a single parent, producing genetically identical offspring.

What is binary fission?

A form of asexual reproduction where a cell divides into two identical daughter cells, common in bacteria.

What is an advantage of asexual reproduction?

It is advantageous in 'good,' steady environmental conditions.

What is an advantage of sexual reproduction?

It is advantageous in changing environmental conditions due to increased genetic diversity.

List examples of asexual reproduction.

Binary fission (bacteria), Budding (hydra), Fragmentation (sponges, potatoes), Vegetative reproduction (runners, crab grass, strawberries).

What is cell differentiation?

The process in multicellular organisms where cells become specialized for a particular function.

How can cells differentiate when they all have the same DNA?

Cells differentiate by expressing different combinations of genes. Determined by their location in the embryo.

What is the hierarchy of biological organization in multicellular organisms?

Cells -> Tissues -> Organs -> Organ Systems -> Organism.

What are stem cells?

Cells with the ability to become different types of specialized cells.

Define totipotent stem cells.

Cells that can give rise to all cell types, including a new organism

Define pluripotent stem cells.

Cells that can give rise to almost any cell type

Define multipotent stem cells.

Cells that can give rise to closely related cell types