AP Bio Unit 6 Vocab

Quorum Sensing

A process where bacteria release and detect signaling molecules to sense population density, coordinating behaviors like biofilm formation or virulence

Taxis

directed movement of an organism toward (positive) or away from (negative) an environmental stimulus

Chemotaxis

a type of taxis where cells or organisms move in response to a chemical gradient, often toward nutrients or away from toxins

Ligands

specific molecules (like hormones, neurotransmitters, or growth factors) that bind to a receptor to initiate a cellular response

Receptors

proteins on the cell membrane or inside the cell that detect signaling molecules and trigger signal transduction pathways

Signal Transduction

the series of molecular events by which a signal from a ligand binding to a receptor is converted into a specific cellular response

Ligand-Gated Ion Channel

a transmembrane protein that opens or closes an ion channel in response to a ligand, allowing ions to flow and change the membrane potential

Catalytic (enzyme-linked) receptor

a receptor that, when a ligand binds, directly activates an intracellular enzyme (often kinase) to trigger a signaling cascade

G-protein linked receptor

a receptor that activates a G-protein upon ligand binding; the G-protein then activates an effector protein, starting a cascade that produces a cellular response

secondary messagers

small molecules like cAMP, Ca2+, or IP3 that relay and amplify signals inside the cell from receptors to target molecules

Homeostasis

the maintenance of stable internal conditions (e.g. temperature, pH, glucose levels) despite changes in the external environment

Negative feedback pathway

a regulatory mechanism where a change in a variable triggers a response that counteracts the initial change to restore balance

Positive feedback pathway

A regulatory mechanism where a change in a variable triggers a response that amplifies the initial change, often leading to a rapid event.

Apoptosis

Programmed cell death controlled by cellular signaling pathways, important for development, tissue maintenance, and removing damaged cells.

Cancer

A group of diseases characterized by uncontrolled cell division caused by disruptions in normal cell cycle regulation.

oncogene

a mutated form of a normal gene (proto-oncogene) that promotes excessive cell division and can lead to cancer

tumor suppressor genes

genes that normally slow down the cell cycle, repair DNA damage, or trigger apoptosis; when they are inactivated, cancer can develop

prophase

the first stage of mitosis in which chromatin condenses into visible chromosomes, the nuclear envelope begins to break down c and spindle fibers start to form

metaphase

the stage of mitosis where chromosomes align at the cells equator, called the metaphase plate

anaphase

the stage of mitosis in which sister chromatids separate and are pulled toward opposite poles of the cell

telophase

the final stage of mitosis where chromosomes decondense, nuclear membranes reform, and the spindle apparatus breaks down

chromatin

a complex of DNA and proteins (histones) that make up chromosomes and is less condensed when the cell is not dividing

spindle fibers

microtubule structures that form during mitosis and attach to chromosomes to move them during cell division

kinetochores

protein structures located at the centromere of each chromosome where spindle fibers attach

metaphase plate

an imaginary plane at the center of the cell where chromosomes line up during metaphase

cytokinesis

the division of the cytoplasm that follows mitosis, producing two separate daughter cells

cleavage furrow

a shallow groove that forms in anima cells during cytokinesis and pinches the cell into two

cell plate

a structure that forms in plant cells during cytokinesis and develops into a new cell wall between the daughter cells