AP Bio - Unit 4 Cell Communication & Cycle

anaphase

paired sister chromatids separate as spindle fibers pull chromatids towards poles

cAMP

relay and amplify intracellular signal

cell plate

formed during cytokinesis between daughter nuclei and expands radially until it fuses with the parental cell walls, typically for plant cells

cell signaling

a process in which cells communicate with each other to coordinate their actions (short distance, long distance, direct touch)

centromere

the center that connects two chromatids together

centrosome

an organelle near the nucleus of a cell which contains the centrioles (in animal cells) and from which the spindle fibers develop in cell division.

checkpoint

control mechanisms that verify whether the cell is ready to proceed to the next phase

cyokinesis

a cleavage furrow forms (animal cells) or cell plate forms (plant cells), resulting in two daughter cells

cyclin

proteins whose levels fluctuate (increase or decrease in amount) throughout the cycle and helps control the timing of the cell cycle

cyclin-dependent kinase (Cdk)

becomes activated when cyclin binds to appropriate cyclin and are phosphorylated

dephosphorylation

the process of removing a phosphate group from a protein, inactives a cell

gametes

sexual reproduction cells that form a zygote

G- protein-coupled receptor

a membrane protein that detects signals (like hormones, neurotransmitters, or light) outside the cell and activates an internal signal transduction pathway through a G protein.

G0 phase

no longer divides but can reenter the cell cycle in response to appropriate cues

G1 phase

cell is metabolically active, duplication organelles and cytosolic components

G2 phase

Protein synthesis occurs, ATP is product in large quantities, and chromosomes replicate

S phase

DNA is in form of chromatin and replicates to form two sister chromatids connected at a centromere

hormone

a chemical messenger produced by endocrine cells that travels through the bloodstream (in animals) or through other transport mechanisms in plants to target cells and regulate specific physiological processes.

insulin

peptide hormone produced by the beta cells of the pancreas that helps regulate blood glucose levels.

interphase

phase of the cell cycle in which the cell grows, performs its normal functions, and prepares for division. It is the longest phase of the cell cycle.

ligand

molecule that binds specifically to a receptor on a cell, triggering a signal or response inside the cell.

ligan-gated ion chanel

membrane protein that opens or closes in response to a specific ligand (signal molecule) binding, allowing ions to flow into or out of the cell.

local regulator

signaling molecule that acts over short distances to affect nearby cells.

metaphase

spindle fibers align chromosomes along the equator of the cell

mitsosis

process of nuclear division, where one nucleus divides to form two genetically identical nuclei, occurs in sequential steps (PMAT) and alternates interphase in the cell cycle

mitotic (M) phase

entire phase of the cell cycle that includes mitosis AND cytokinesis.

mitotic spindle

structure made of microtubules that forms during mitosis and is responsible for separating sister chromatids and guiding them to opposite poles of the cell.

MPF

protein complex that triggers a cell to enter mitosis (M phase) from the G₂ phase of interphase.

neurotransmitters

a kind of ligand, usually used for long distance cell signaling

phosphorylation

gaining a phosphate group to a protein, activates the cell

phosphorylation cascade

series of protein activations in which one enzyme phosphorylates the next, amplifying a signal and leading to a specific cellular response.

prophase

sister chromatids condense, mitotic spindle begins to form, centrosomes move toward opposite poles of the cell

protein kinase

enzyme that transfers a phosphate group from ATP to a protein, usually on serine, threonine, or tyrosine residues, which changes the protein’s activity.

protein phosophatase

enzyme that removes phosphate groups from proteins, often reversing the action of protein kinases and altering the protein’s activity.

second messenger

small molecule or ion inside a cell that relays a signal from a receptor on the cell surface to trigger a specific cellular response.

signal transduction pathway

series of molecular events by which a cell converts an extracellular signal (like a hormone or ligand) into a specific cellular response.

somatic cells

all the body cells of an organism except the reproductive (gamete) cells.

telophase

mitotic spindle breaks down, a new nuclear envelope develops, and then the cytoplasm divides

transduction

receptor converts the signal into a form that can bring about a cellular response.

negative feedback group

regulatory mechanism in which a change in a system triggers a response that counteracts that change, helping maintain homeostasis (two products)

positive feedback group

regulatory mechanism in which a change in a system triggers a response that amplifies that change, rather than reversing it.

Apoptsis

form of programmed cell death that occurs when a cell undergoes a controlled and orderly process of self destruction