Chapter 7: Cell Communication and Cell Cycle

Ligand-gated ion channels

Receptors that open or close an ion channel upon binding a particular ligand.

Catalytic receptors

Receptors that have an enzymatic active site on the cytoplasmic side of the membrane and initiate enzyme activity by ligand binding at the extracellular surface.

G-protein-linked receptor

Receptors that bind a different version of a G-protein on the intracellular side when a ligand is bound extracellularly, causing activation of secondary messengers within the cell.

Homeostasis

The set of conditions under which living things can successfully survive.

Insulin and Glucagon

Two hormones released from the pancreas that regulate blood glucose levels.

Negative Feedback Pathway

A pathway that works by turning itself off using the end product of the pathway, inhibiting the process from beginning, thus shutting down the pathway.

Positive Feedback Pathway

A pathway that involves an end product playing a role, and instead of inhibiting the pathway, it further stimulates it.

Cell Cycle

The period from the beginning of one division to the beginning of the next in a cell's life cycle.

Interphase and Mitosis

The two periods that the cell cycle is divided into.

Interphase

The growing phase of the cell cycle between two cell divisions.

Three stages of Interphase

Interphase can be divided into three stages: G1, S, G2.

S phase

The most important phase of interphase where the cell replicates its genetic material.

Chromosome Duplication

During interphase, every single chromosome in the nucleus is duplicated, and these identical strands of DNA are called sister chromatids.

Centromere

The structure that holds together the sister chromatids.

Chromatids

The identical strands of DNA formed during chromosome duplication that are held together by a centromere.

Full-fledged Chromosomes

Once the chromatids separate, they become full-fledged chromosomes, and each chromosome has its own centromere.

Mitochondria

Organelles in cells that convert energy from organic molecules into ATP, the most common energy molecule in the cell.

Cell Cycle Checkpoints

Control mechanisms in eukaryotic cells that regulate cell division by ensuring proper progression through G1, S, G2, and M phases, and activate when damaged DNA is found.

CDKs and Cyclins

Two families of proteins that regulate cell cycle progression. An inactive CDK binds a regulatory cyclin to induce cell cycle progression, while CDKs and cyclins are kept separate to inhibit cell cycle progression.

Cancer

Abnormal growth and spread of cells to other parts of the body.

Oncogenes

Mutated genes that can convert normal cells into cancerous cells.

Proto-oncogene

Healthy version of a gene that can become an oncogene if mutated.

Tumor suppressor genes

Genes that produce proteins to prevent the conversion of normal cells into cancer cells.

CDK/cyclin complexes

Proteins that work with tumor suppressor genes to stop cell growth until damage can be repaired.

Apoptosis

Programmed cell death triggered by tumor suppressor genes if damage is too severe to be repaired.

Mitosis

The process of cellular division that occurs in four stages: prophase, metaphase, anaphase, and telophase.

Interphase

The initial phase of the cell cycle, where the chromosomes decondense and become invisible, and the genetic material is called chromatin again.