Chapter 11 Flashcards
Quorum sensing
When bacteria monitors their own local cell density Allows bacterial populations to coordinate the behavior of all cells in a population In activities that require a given density of cells acting at the same time
What are the 3 steps of signal transduction pathway?
- Signal reception 2. Signal transduction 3. Cellular response
What is paracrine signaling?
Type of local signaling. Stimulate nearby cells to grow and divide
What is synaptic signaling?
An electrical signal along a nerve cell triggers the secretion of neurotransmitter molecules
Hormones / endocrine signaling
Molecules for long distance signaling.
Endocrine signaling
Specialized cells release hormones which travel through circulatory systems to other parts of body where they reach target cells
Ovary/testee gland that produce sex hormones
Adreneal gland - produces ephinephrine
Pancreas - releases insulin and glucagon
What is cell surface molecule signaling?
Cell surface molecules on adjacent cells interact with each other resulting in signaling passing between cells GPCRs
What are the types of local and long distance signaling?
Direct contact: cell junction & cell surface molecule
Local: paracine & synaptic
Long distance: endocrine signaling
What happens durning signal reception?
The target cells detection of a signaling molecule coming from outside the cell. The signaling molecule binds to a receptor protein located at the cells surface
What is signal transduction?
Converts the signal to a form that can bring about a specific cellular response
Signal transduction pathway
Series of steps in transduction Sequence of changes in a series of different molecules
What is cellular response?
The transduced signal finally triggers a specific cellular response
Ligand
Term for a molecule that specifically binds to another (often larger) molecule
What are the 3 types of cell surface transmembrane receptors?
GPCRs Receptor
tyrosine kinases
Ion channel receptors
G protein-coupled receptor
a cell surface transmembrane receptor that works with the help if a G protien, a protein that binds the energy rich molecule of GTP
- Ligand attaches to receptor changes shape
- G protein becomes active and diffuses to receptor which creates GTP
- Ligand detaches and G protien becomes inactive again
- G protien attaches to a enzyme
Recepto tyrosine kinases or RTK’s
an enzyme that catalyzes the transfer of phosphate groups from ATP to another protein
- Ligand attach to both receptors which brings them together to make a dimer
- Tyrosine then becomes active and takes phosphates from ATP
- This attracts relay proteins which undergo a change in shape and creates a transduction pathway and cell response
**multiple cell responses can come from this dimer
ion channel receptors
type of membrane channel receptor containing a region that can act as a gate, opening or closing the channel when the receptor changes shape
ligand does not go through but allows ions to pass when channel is open
What is an intracellular receptor
found in the cytoplasm or nucleus of target cells. to reach such a receptor a signaling protein passes through the target cells plasma membrane
Protein kinase
an enzyme that transfers phosphate groups from ATP to a protein
Protien that adds a phosphate
Phosphorylation cascade
a pathway of a sequence of steps each causing a shape change in the phophorylated protien.
Protein phosphates
enzymes that can rapidly remove phosphate groups from protiens a process called dephosphorylation
Protein that removes a phosphate
Second messengers
small non protein water soluable molecules or ions 2 most common are Cyclic AMP and calcuim ions (Ca2+)
Ligand is the first messanger.
Cyclic AMP
a small molecule produced from ATP
2nd messenger
Adenylyl cyclase
an enzyme embedded in the plasma membrane converts ATP to cAMP
