AP BIO UNIT 4: Cell Communication and Cell Cycle

Taxis

Taxis

the movement of an organism in response to a stimulus and can be positive (toward the stimulus) or negative (away from the stimulus)

Short-range cell communication

affecting only nearby cells

Long-range cell comunication

affecting cells throughout the organism

Ligands

signaling molecules the bind to receptors and triggers a response by changing the shape of the receptor protein

Signal Transduction

the process by which an external signal is transmitted to the inside of a cell

Membrane receptor

required for when signaling molecules cannot enter the cell

Ligand-Gated Ion Channels

located in the plasma membrane, open or close an ion channel upon binding a particular ligand

Catalytic (enzyme-linked) receptors

enzyme activity us initiated by ligand binding at the extracellular surface

G-protein-linked receptor

binds to a different version of a G-protein, causes the activation of secondary messengers, like cyclic AMP, within the cell

Signal transduction cascade

helpful to amplify a signal

Homeostasis

the set of conditions under which living organisms can successfully survive

Insulin

a hormone that regulates blood sugar levels

Feedback inhibition

a negative feedback pathway

Cell cycle

the cell’s life cycle

Interphase

the time span from one cell division to another

Mitosis

the cellular division of body cells

The three stages of interphase:

G1, S, G2

S phase

when the cell replicates its genetic material

Sister chromatids

identical strands of DNA

Centromere

a structure that holds chromatids together

G1 and G2

when the cell preforms metabolic reactions and produces organelles, proteins, and enzymes

Cyclin-dependent kinases (CDKs)

special proteins that regulate the checkpoints during the cell cycle

G0

where damaged DNA goes to be fixed or deleted

Cancer

when normal cells start behaving and growing very abnormally and spread to other parts of the body

Oncogenes

mutated genes that induce cancer

Proto-oncogene

genes that can convert normal cells into cancerous cell

Tumor suppressor genes

produce proteins that prevent the conversion of normal cells into cancer cells

Prophase

the nuclear envelop disappears and chromosomes condense

Metaphase

when chromosomes align at the metaphase plate and mitotic spindles attach to kinetochores

Anaphase

chromosomes are pulled away from the center

Telophase

formation of two new nuclei

Cytokinesis

the separation of cytoplasm and formation of 2 identical daughter cells