Cell Communication, Cell Division, and the Cell Cycle

Vocabulary flashcards covering cell communication, stages of the cell cycle, mitosis, meiosis, apoptosis, and cell cycle checkpoints in cancer.

Reception

The first step of cell communication, occurring when a ligand binds to a receptor.

Transduction

The stage of cell communication where a signal is passed along, often amplified by a phosphorylation cascade.

Response

The final step of cell communication in which the cell carries out an action, such as turning on a gene or activating an enzyme.

Blocked Receptors

A cell communication issue where poisons or neurotoxins obstruct receptors so that a signal is never received.

Mutated Ras Protein

An example of faulty transduction in cancer where a mutated protein continuously sends a "divide" signal even without a ligand.

Type 1 Diabetes

A cell communication disorder caused by a missing signal, in which the pancreas fails to produce the insulin ligand.

$G_1$ (Gap 1)

The stage of interphase where the cell grows, carries out normal functions, and duplicates organelles.

S (Synthesis)

The phase of interphase during which DNA is replicated, converting chromosomes from a single chromatid to two sister chromatids.

$G_2$ (Gap 2)

The interphase phase where the cell continues to grow and prepares for division by checking DNA for errors.

M Phase

The stage of the cell cycle consisting of mitosis or meiosis (division of the nucleus) and cytokinesis.

Cytokinesis

The division of the cytoplasm and the rest of the cell following nuclear division.

$G_0$ Phase

A non-dividing, resting state of the cell cycle where cells like mature neurons reside permanently.

Mitosis

Nuclear division in somatic/body cells that produces two identical, diploid ($2n$) daughter cells for growth and repair.

Prophase (Mitosis)

The first phase of mitosis, during which chromatin condenses into visible chromosomes, the nuclear envelope breaks down, and spindle fibers form.

Metaphase (Mitosis)

The stage of mitosis where chromosomes line up single-file down the middle (equator) of the cell.

Anaphase (Mitosis)

The mitotic stage in which sister chromatids are pulled apart toward opposite poles of the cell.

Telophase (Mitosis)

The mitotic stage where two new nuclei form around the separated chromosomes, and the chromosomes uncoil.

Meiosis

Nuclear division in sex cells (gametes) consisting of two rounds of division to produce four genetically unique, haploid ($n$) daughter cells (sperm/egg).

Meiosis I

The first round of meiotic division that separates homologous chromosomes (maternal and paternal pairs) via PMAT I.

Meiosis II

The second round of meiotic division that separates sister chromatids via PMAT II, functioning just like mitosis.

Crossing Over

A meiotic process occurring in Prophase I where homologous chromosomes pair up (synapsis) and trade pieces of DNA to form recombinant chromosomes.

Independent Assortment

A process during Metaphase I where homologous chromosome pairs line up randomly at the equator, making maternal and paternal orientation a coin flip for each pair.

Apoptosis

Programmed cell death ("cellular suicide") where caspases break down the cell from the inside out before it is consumed by scavenger cells.

Caspases

Enzymes that dismantle the cell from the inside out during apoptosis.

Cancer

Uncontrolled cell division resulting from a loss of cell cycle regulation.

$G_1$ Checkpoint

The critical regulatory checkpoint where a cell stops to repair damaged DNA or trigger apoptosis; failure here allows damaged DNA to be replicated during S phase.

p53

A tumor suppressor gene that halts the cell cycle at the $G_1$ Checkpoint to repair damaged DNA or trigger apoptosis; when mutated, cells bypass the checkpoint and divide uncontrollably.