Cell Division and Cell Cycle

G1 Checkpoint

Checks for DNA damage and favorable environmental conditions.

G2 Checkpoint

Checks that DNA and centrosomes have been copied, DNA is undamaged, and cell size is adequate.

Spindle Checkpoint (M Checkpoint)

Ensures that the 2 copies of DNA are properly attached to mitotic spindles.

External Factors in Cell Cycle

Signals from outside the cell that direct cells to speed up or slow down the cell cycle.

Contact Inhibition

External factor where cells stop dividing once they touch other cells.

Growth Factors

Proteins that stimulate cell division, crucial for wound healing and embryonic development.

Internal Regulators

Proteins like cyclins and kinases that respond to events occurring inside the cell.

Cyclins

Proteins that interact with kinases to regulate the cell cycle; rapidly made and destroyed at specific points.

Cyclin Discovery Experiment

Injecting a protein from a mitotic cell into a non-dividing cell caused mitotic spindles to start forming.

Kinases

Enzymes that transfer a phosphate group to a target molecule, causing a shape change.

CDKs (Cyclin-Dependent Kinases)

Kinases that control the cell cycle and are activated by cyclins.

Cancer Cell Characteristics

Cells that do not respond to normal regulatory signals, have an out-of-control cell cycle, and grow rapidly.

Benign Tumors

Disorganized clumps of cells that remain clustered together and can be surgically removed.

Malignant Tumors

Tumors that break away (metastasize) and form new tumors around the body.

How Cancer Spreads

Cancerous cells travel through the blood or lymphatic system to other areas of the body.

Carcinogens

Substances known to promote or cause cancer by damaging genes.

TP53 Gene & p53 Protein

The 'Guardian of the Genome' that regulates division by binding to DNA to trigger repair or apoptosis.

Standard Cancer Treatments

Surgery (remove tumor), radiation (destroy DNA), and chemotherapy (kill/slow growth); cons include killing healthy cells.

Apoptosis

Programmed cell death involving a controlled series of self-destruction steps via enzymes (e.g., removing webbed fingers).

Necrosis

Cell death due to injury or trauma that often causes inflammation in surrounding cells.

Cell Differentiation

The developmental process by which unspecialized cells become specialized in structure and function.

Stem Cells

Unspecialized cells that can divide, self-renew, remain unspecialized, and develop into specialized cell types.

Adult Stem Cells

Stem cells found in mature tissues that are typically hard to isolate and grow in culture.

Embryonic Stem Cells

Pluripotent stem cells that can grow indefinitely in culture, though their use raises ethical issues.

Totipotent Stem Cells

Stem cells that can develop into ANY cell in the body, including extraembryonic membranes and the placenta.

Pluripotent Stem Cells

Cells capable of developing into most, but not all, of the body's cell types.

Multipotent Stem Cells

Stem cells found in bone marrow, brain, and muscle that can grow into cells of a closely related family.

Limits to Cell Size

The surface area-to-volume ratio limits cell size to ensure efficient transport of nutrients and wastes.

Genes

Regions on DNA that carry the genetic code necessary for making proteins.

Chromatin

The uncondensed combination of DNA and protein that is too thin to see under a light microscope.

Chromosomes

The condensed form of DNA and protein; humans have 46 chromosomes (23 pairs).

Telomeres

The protective ends of chromosomes that shorten after each cell division, signaling the cell to stop when too short.

Sister Chromatids

Two identical, joined copies of a chromosome produced during DNA replication in the S phase.

Centromere

The specific region where sister chromatids are tightly joined together.

Homologous Chromosomes

A pair of matching chromosomes; human somatic cells are diploid (2n=46) while gametes are haploid (n=23).

Binary Fission

Asexual cell division used by bacteria where a single chromosome replicates, attaches to the membrane, and pinches apart.

Mitosis vs. Meiosis

Mitosis produces 2 identical diploid somatic cells for growth/repair; meiosis produces 4 unique haploid gametes.

Interphase G1 Phase

Cell grows, acquires ATP, and synthesizes proteins; non-dividing cells exit the cycle here.

Interphase S Phase

All DNA in the cell is replicated along with key associated chromosomal proteins.

Interphase G2 Phase

Usually the shortest phase of interphase, producing organelles and molecules required for mitosis.

Mitosis M Phase

The shortest part of the cell cycle where nuclear division and cytokinesis occur.

Prophase

Chromosomes condense, nuclear envelope breaks down, and centrosomes move to opposite poles to form spindle fibers.

Metaphase

Spindle fibers fully form and pull chromosomes to the center along the metaphase plate.

Anaphase

Centromeres divide, sister chromatids separate to opposite poles, and non-attached microtubules push poles further apart.

Telophase

Chromosomes de-condense into chromatin, nuclear envelopes reform around two new nuclei, and nucleoli reappear.

Cytokinesis in Plant Cells

Separation is accomplished by a cell plate forming between chromatin masses, building a new cell wall and membrane.

Cytokinesis in Animal Cells

A ring of microfilaments under the plasma membrane pinches the center like a drawstring (cleavage furrow).

Bolivia's Two Capitals

La Paz is the administrative capital, and Sucre is the constitutional and judicial capital.

Internal vs. External Regulators

Internal regulators respond to events inside the cell; external regulators come from outside.