Cell Receptors and Transduction Pathways Flashcards Preview

AP Biology 2014 > Cell Receptors and Transduction Pathways > Flashcards

Flashcards in Cell Receptors and Transduction Pathways Deck (14)
Loading flashcards...
1
Q

Cell junctions in plants and animals

A

Directly connect the cytoplams of adjacent cells

  • Animals: gap junctions
  • Plants: plasmodesmata

–> signaling substances in the cytosol can pass freely between adjacent cells

2
Q

Growth Factors

A

Class of local regulators that stimulate nearby target cells to grow and divide

3
Q

Paracrine signaling

A

Multiple cells recieve and respond to a signal sent by one cell

  • local signaling
4
Q

Synaptic Signaling

A

One cell receives and responds to a signal sent directly to that cell

  • Occurs in animal nervous system
  • Electric signal moving along a nerve cell triggers the secretion of neurotransmitter molecules carrying a chemical signal
  • Molecules diffuse across a synapse (space between nerve cell and target cell)–> triggers a response in the cell
  • local signaling
5
Q

Endocrine signaling

A

Hormonal signaling, long distance

Cells release hormones that travel via the circulatory system to responsive target cells in other parts of the body

  • Plant hormones travel mostly through vascular tissue (xylem / phloem), but some travel through air as gas
  • Common animal hormone: epinephrine
6
Q

Three stages of cell signaling

A
  1. Reception- target cell’s detection of a signaling molecule coming from outside the cell
  2. Transduction- a step or series of steps that converts the signal that causes a specific cellular response
  3. Response- transduced signal triggers cellular response
7
Q

Ligand

A

A molecule that specifically binds to another molecule, usually causing the receptor to change shape, which activates the receptor

  • Signaling molecules generally act as ligands to receptor proteins on target cells
8
Q

G protein-coupled receptor (GPCR)

A

A cell surface transmembrane receptor that makes use of a G protein (protein that binds GTP)

  • After receptor protein binds and changes shape, its cytoplasmic side binds and activates a G protein
  • Activated G protein carries a GTP molecule
  • Leaves the receptor, diffuses along the membrane, and then binds to an enzyme that triggers the rest of the reaction
9
Q

Ligand-gated ion channel

A

A membrane receptor that has a region that can act as a “gate” for ions when the receptor assumes a certain shape

  • Regulates passage of specific ions across membrane
  • Example: sodium potassium pump
10
Q

Transcription factors

A

Proteins that control which genes are turned on / transcribed into mRNA

  • Receptors act as transcription factors that turn on other genes
11
Q

Steroid hormone

A

Chemical messenger that passes through the cell membrane to reach a receptor

  • Hydrophobic (nonpolar) enough to cross the cell membrane
  • Example: testosterone
12
Q

Protein kinase

A

An enzyme that transfers phosphate groups from ATP to a protein

  • Participates in signaling pathways in animals, plants, and fungi
  • Many relay molecules in signal transduction pathways are protein kinases, often acting on other protein kinases in the pathway
13
Q

Protein phosphatases

A

Enzymes that quickly remove phosphate groups from proteins (dephosphorylation)

  • By dephosphorylating and thus inactivating protein kinases, phosphates turn off the signal transduction pathway when the initial signal is no longer present
14
Q

Second messengers

A

Small, nonprotein water-soluble (polar) molecules or ions involved in signaling pathways

  • Small size allows them easily spread throughout the body by cell division
  • Calcium Ions
    • ​A signal relayed by a signal transduction pathway may trigger an increase in calcium in the cytosol
  • Cyclic AMP
    • Epinephrine binds to the plasma membrane of a liver cell, heightening the cytosolic concentration of cAMP
    • cAMP broadcasts signal to cytoplasm
    • Does not exist for long without the hormone because another enzyme converts cAMP back to AMP