AP Bio Unit 4 Communication

Signal Transduction Pathway

Series of steps by which a signal is converted into a cellular response

Ligand

Signaling molecule that binds to a receptor

Receptor Protein

Protein that receives a signal molecule

Cell-Surface Receptor

Receptor located on the plasma membrane

Intracellular Receptor

Receptor inside the cell that binds hydrophobic ligands

G Protein-Coupled Receptor

Receptor that activates a G protein

Receptor Tyrosine Kinase

Receptor that phosphorylates itself

Phosphorylation Cascade

Chain of protein activations via phosphate groups

Second Messenger

Small molecule that relays signals inside the cell

cAMP

Second messenger involved in signal amplification

Signal Amplification

Increase in signal strength during transduction

Response

Cellular outcome of a signal

Cell Cycle

Ordered series of events leading to cell division

Interphase

Growth and DNA replication phase

G₁ Phase

Cell growth phase

S Phase

DNA synthesis phase

G₂ Phase

Preparation for mitosis

Mitosis

Division of the nucleus

Prophase

Chromosomes condense and spindle forms

Metaphase

Chromosomes align at the cell equator

Anaphase

Sister chromatids separate

Telophase

Nuclear membranes reform

Cytokinesis

Division of the cytoplasm

Cyclin

Regulatory protein controlling cell cycle progression

CDK

Cyclin-dependent kinase

Checkpoint

Control point in the cell cycle

Apoptosis

Programmed cell death

Cancer

Uncontrolled cell division