AP Bio Unit 5 CELL SIGNALING

Reception (signal transduction pathway)

target cell's detection of a signaling molecule coming from outside the cell;
The binding between a signal molecule (ligand) and receptor is highly specific (lock & key) and generally causes a shape change in the receptor, activating the receptor

Ligand

Signaling molecule

Ligand ion channel receptor

When a ligand binds to the receptor, the gate allows specific ions, such as Na+ or Ca2+, through a channel in the receptor

G-protein coupled receptor (GPCR)

1. Ligand molecule binds to specific G protein-couple receptor, changing its shape, & activating it
2. GPCR binds & activates G protein
3. G protein then leaves receptor & binds to enzyme, changing its shape, and activating it

Transduction

Step or series of steps that converts the signal to a form that can bring about a specific cellular response

Protein kinase

An enzyme that transfers phosphate groups from ATP to a protein

Signal transduction pathway

1. reception
2. transduction
3. response

Homeostasis

Maintaining stable internal conditions as environment changes; examples include body temperature, glucose levels, osmolarity, pH

Hormone

Type of secreted chemicals by the endocrine system that are important in long-distance signaling- travel in body fluids and act on specific target cells in other parts of the body; examples include insulin (released with high blood glucose levels) and glucagon (released with low blood glucose levels)

Negative feedback

Maintaining set point; examples include body temperature, blood glucose levels, osmolarity, pH

Osmolarity

The solute concentration of a solution

Positive feedback

Amplifies/ reinforces stimulus; examples include ethylene, blood clotting

Intracellular domain

Inside portion of a membrane embedded receptor protein

Signal cascades

Amplify and distribute intracellular (inside the cell) signals; occurs in cytoplasm

cAMP

Secondary messenger that relays and amplifies intracellular (inside the cell) signals

Chromatid

One half of a duplicated chromosome

Centromere

Region of a chromosome where the two sister chromatids attach

Interphase

Cell grows, copies DNA, and prepares for division; consists of G1, S, and G2 phases

G0 stage

A nondividing state occupied by cells that have left the cell cycle, sometimes reversibly.

Growth factors

Proteins released by certain cells that stimulate other cells to divide

Cyclin

One of a family of proteins that regulates the cell cycle in eukaryotic cells

Apoptosis

Programmed cell death

Cancer

A disease in which some body cells grow and divide uncontrollably, damaging the parts of the body around them.